Human evolution: relationships with other species and with the environment they occupied
Sediments deposited in the site at la Gran Dolina cover a space of time of over a million years. Some of its geological levels have provided hundreds of fossils of species which inhabited the sierra de Atapuerca at different periods of the Pleistocene. Their study and identification enable us to obtain data about the climactic conditions, vegetation and fauna at specific periods. Large and medium-sized mammals were caught by humans and by certain predators of the time (lions, sabre-tooth tigers, hyenas and canines). In particular, the species of amphibians, birds, small mammals and reptiles are very similar to those of today, whose tolerance to temperature and humidity is well-known. The combination of fossil remains of these species at a certain geological level, together with the presence of pollen from plant species, allows us to know very precisely what the environment was like and to reconstruct the landscapes in which the humans of the Pleistocene lived. The clay, sand and silt which make up different sedimentary layers also inform us about environmental conditions in the past. They are linked to natural phenomena such as the wind, rain or temperature and are therefore a very valuable source of information, even in the absence of fossil remains.
Humans began to occupy the entrance to the cave over more than 400,000 years ago. They took their catches there to cut them up and share with all the members of the group. They also made their tools from blocks of flint found near the cave, which was a central spatial reference for the group. Hunting was very selective. On one of the “archaeological” levels only skeletal remains of bison have been found. On other levels, remains of horses and several species of deer predominate.
The humans who wandered around the Sierra de Atapuerca over 850,000 years ago had no special interest in the caves and probably lived outside. The stone tools found on the older levels of Gran Dolina are very few. Perhaps these humans visited this and other caves in the area in search of the meat of some animal trapped inside. However, predators and carrion-eaters have left evidence of their presence in the cave’s entrance. Coprolites (fossilized remains of excrement) and tooth marks on their prey’s bones are quite common.
Ultimately, sites such as the cave at la Gran Dolina are a very valuable source of information for understanding the way of life and relationship with other species of the European human species which preceded us, and with the environment in which they evolved.
José María Bermúdez de Castro, Professor of Research at CSIC, and co-director of the Atapuerca site (Burgos, Spain)