Atapuerca's place in human evolution

Burgos is a medium-size historical town situated a little over two hundred kilometres north of Madrid, the capital of Spain. The gently rolling hills, known as the Sierra de Atapuerca (Unesco World Heritage Site), lie a few kilometres east of Burgos in the north-eastern corner of the Castilian plateau.
Although there is some farming, the hills are largely covered with scrub. Water erosion over millions of years has left an elaborate limestone cave system in the area with openings which are clearly visible from outside. For nearly one million years, these caves have provided shelter for humans as well as animals. Over the millennia, the inhabitants of Atapuerca -- animals, sub-humans and humans -- left behind an extraordinary fossil record that scientists are just beginning to unearth.
The local people were aware of the existence of these dark caverns and some even found animal teeth and bones while occasionally taking shelter in them because of sudden changes in weather conditions. Since it was considered dangerous to venture deep into the caves, the archaeological contents of the caves remained secret for thousands of years.
They would have remained so for many more years had it not been for the fact that in late nineteenth century (there is some controversy over the exact year), a railroad company, while building a deep trench through the mountain range to lay tracks, came upon this extraordinary archaeological treasure which "constitute the most expansive fossil record of the Pleistocene Epoch (which began around 1.8 million years ago and lasted until around 10,000 years ago) of Europe and is also the setting where a new species of hominid, Homo Antecesor was discovered."
It is no secret that we, the modern human beings, have always been curious about the origin of man and his relations with other animals. This is also true that there have been great controversies over this subject. But "the prevailing opinion among men of science is that like other mammals, man is descended from ancestors of a lowlier kind, that he and the large apes, the chimpanzee, the orang-utan and the gorilla, had once a common ancestor, and this ancestor was evolved from yet lower forms, from some earlier type of mammal which was itself descended from a reptile, and this again from a series of amphibians, and these again from primitive fish."
According to the scientists, "in the case of many of the great mammals it is possible to trace the descent of the existing species almost step by step from an Eocene ancestor. This is so with elephants, for example, camels and horses. The series in these instances are very complete." Unfortunately, it is not so in the case of the man. Fossil remains of our human ancestors are not abundant and until very recently there were broad gaps in the chain of human evolution. In other words, in their efforts to trace the step by step descent from our ancestors to the man, scientists could not account for some of the steps that they felt were missing.
According to some scientists, the fossil remains of Homo Antecesors, or sub-men found in the caves of Atapuerca, seem to bridge this gap. (This does not necessarily exclude the existence of other varieties of sub-men in other parts of the world.) In the case of the sub-men who lived at Atapuerca "the teeth, the brain cases, the carriage of the head and the slope of the forehead are more human than any ape's and more simian than any recorded human being's."
Excavations in Layer 6 of Gran Dolina cave have yielded a rich assortment of fossils, including those of early European sub-humans (Homo Antecesors) that date back some eight hundred thousand years, who not only hunted animals for food with stone tools --thousands of bone fragments from other animals have been found -- but also practiced cannibalism.
Another cave called Sima de los Huesos (The Pit of Bones) testifies to the fact that Atapuerca, due to its special ecosystem and location, was home to a variety of hominid species for hundreds of thousands of years. In this cave, scientists have discovered bones from thousands of hominid fossils together with bones from bears, lions, foxes and wolves.
The Pit of Bones is home to the largest collection of ancient fossils in the world. Scientists are convinced that the fossils did not belong to the Homo Antecesors (more than 800,000 years ago) but to a more advanced species who were more akin to the Homo Hiedelbergensis who lived more than 350,000 years ago. The first jaw-bone of this species was found in a sandpit near Heidelberg, hence the name.
Approximately two kilometres away from the Gran Dolina site near the river Pico, scientists have also discovered numerous archaeological vestiges of long occupation of the area by the Neanderthals who lived in Europe and parts of western Asia for more than 100,000 years and disappeared approximately 40,000 years ago because, according to most scientists, they could not interbreed with Homo Sapiens -- modern humans -- who arrived in Europe from Africa more or less at that time. But according to some scientists, these two species of hominids (the Neanderthals and the Homo Sapiens) co-existed for several hundred years in Europe before the Neanderthals disappeared completely.
The caves of Atapuerca have already yielded priceless information about human evolution and the way our ancestors used to live. Excavations are still continuing on an ongoing basis at various sites in this region, such as la Cueva Peluda, la Cueva Ciega and el Mirador etc., where evidence of human activity over a long period of time has been discovered. A number of ancient cave paintings with geometrical motifs and hunting scenes have been uncovered at the Galeria site. No doubt, further excavations will throw more light on this fascinating subject.

The writer is an Officer of the Order of Queen Isabel I of Spain and a Daily Star columnist.