Scientists have long puzzled over the origin and evolution of our closest relative, the Neanderthal. Now, researchers say that Neanderthals seem to have developed their distinctive jaws and other facial features first, before they evolved to have big brains.
That's according to an analysis of 17 skulls, all taken from one excavation site in a mountain cave in Atapuerca, Spain known as the Sima de los Huesos — the "pit of bones."
This shaft inside the cave yielded a huge number of bones, the biggest collection of ancient human fossils ever recovered from a single site. Since 1984, scientists have been painstakingly removing thousands of bone fragments and assembling them.
These skulls show Neanderthal features in the face and teeth, but have more primitive-looking braincases, according to a report in the journal Science from a research team led by Juan Luis Arsuaga of Madrid's Complutense University. The work shows that the start of the evolution of the Neanderthals began at least 430,000 years ago.
"If we understand how Neanderthals evolved and what has been going on, exactly, in the course of Neanderthal evolution, then we could say what is special with us, what is different," says Jean-Jacques Hublin, who studies human evolution at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
While the Neanderthals were emerging, the ancestors of modern humans were evolving in Africa. Then, around 50,000 years ago, some of those modern humans ventured into Europe, where they apparently out-competed their more-lumbering cousins, who went extinct.
Both Neanderthals and modern humans developed big brains, but they took different paths, says Hublin.
"By studying the divergence between Neanderthals and modern humans, we can understand what happened in our recent evolution," he says, "and maybe why we expanded in such a dramatic way all over the planet."