The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin

The stages of postnatal life
Left, 1929. «Tornado over Kansas», John Steuart Curry © Muskegon Museum of Art (Michigan, USA). Right, circa 1910. Shuar indigenous (named ‘jíbaros’ or ‘jíbaros’ by the Europeans and European Americans), Peruvian Amazone © Museo Nacional de Antropología (Madrid, Spain)

Infants and their feeding
Left, 1585. «The Family of St. Anne», Marten de Vos © Museum voor Schone Kunsten (Ghent, Belgium). Right, 2016. «Restoring the Art of Breastfeeding», Miriel Smith © Artprize (reprinted with the kind permission of the artist)

Babies are a focus of social interest
Left, chimpanzees grooming an infant, photographer: Michel Gunther © World Wildlife Fund. Right, «Baby shower planning». Source: The Baby Centre. Public domain

Baby technology —a part of human culture
A collage of technology related to infant care. Top row from left: 1960. A pacifier (Spain) © Museo Nacional del Traje (Madrid, Spain). 325-290 BC. A clay vessel to collect breastmilk (Italy) © Museo Arqueológico Nacional (Madrid, Spain). Circa 1920. A glass vessel for infant feeding © Museo Nacional del Traje (Madrid, Spain). 1800/1900. Liana ball, Manila (Philippines), photographer: Clara Sánchez © Museo Nacional de Antropología (Madrid, Spain). Botton row from left: 1850. A doll baby, a toy bassinet and a miniature infant bed for a dollhouse (Catalonia, Spain) © Museo Nacional del Traje (Madrid, Spain). 1940-1949. English pram © Museo Nacional del Traje (Madrid, Spain)

How people grow in size and in shape
Figures (A) and (B), 'distance' and 'velocity' curves of growth in height by sex. Source: original figures of the author © Barry Bogin. Figure (C), 1909. detail of a figure from Stratz (1909) ('ann', year) CC license

Measuring growth
Left, 2000. Measuring height of Maya-American girl in Los Angeles (USA) © Barry Bogin. Right, late 1970s. Measurement of height and grip strength (Guatemala) © James Loucky & Barry Bogin.

Infant, family, social status
1765. «George Clive and his family with an Indian maid», Joshua Reynolds © Staatliche Museum (Berlin, Germany)

Girls and boys together
Left, 1998. Havana tea party, Havana (Cuba). Right, 1992. Maya-American school children, Florida (USA) © Barry Bogin

Play defines human childhood
Left, 1998. Bother age 10 years and sister age 7 years at exercise play © Barry Bogin. Right, play peaks during childhood. Source: Bogin (2020) © Cambridge University Press

Boys and girls apart
2014. Secondary students at Igberè, Donga (Benin), Ramón Herrera Otal © Fundación Alaine. Right, 1970s. Maya girls (Guatemala) © Barry Bogin