Skulls Uncovered from 'Pit of Bones' Shed Light on Neanderthal and Human Evolution

Researchers are learning a bit more about the evolution of Neanderthals. They've uncovered a collection of ancient skulls in a cave that have both Neanderthal-derived features and features associated with more primitive humans. The findings shed a bit more light on the history of Neanderthal evolution.

The Middle Pleistocene, which occurred about 400 to 500 thousand years ago, was a time when archaic humans split off from other groups in Africa and East Asia and ultimately settled in Eurasia. There, they evolved characteristics that would come to define the Neanderthal lineage. Several hundred thousand years after that, modern humans, who had evolved in Africa, settled in Eurasia, as well.

"The Middle Pleistocene was a long period of about half a million years during which hominin evolution didn't proceed through a slow process of change with just one kind of hominin quietly evolving toward the class Neanderthal," said Juan-Luis Arsuaga, one of the researchers, in a news release.

In fact, the degree of differentiation between Neanderthals and humans over this short period of time is somewhat surprising. Yet the Sima de los Huesos site In Atapuerca, Spain has now revealed the bones of 28 individuals, including skulls. This, in particular, is useful for understanding evolution.

The researchers found that the skulls showed Neanderthal features in the face and teeth, but not elsewhere. For example, the braincase still showed features association with more primitive hominins.

"We think based on the morphology that the Sima people were part of the Neanderthal clade, although not necessarily direct ancestors to the classic Neanderthals" said Arsuaga in a news release.

In fact, these latest findings show that there was a lot of diversity among different populations in the Middle Pleistocene. In fact, other Homo sapiens during this time period did not exhibit the suite of Neanderthal-derived features seen in this fossil group, which means that more than one evolutionary lineage coexisted at this time.

The findings are published in the journal Science.