How Neanderthals' eyes contributed to their demise

We've heard a lot of different theories attempting to explain why the hardy Neanderthals went extinct, but this one's probably the most original, if not the strangest. According to a new study, Neanderthals had extraordinarily good vision — an attribute that came at considerable expense.

Earlier studies showed that Neanderthals featured skulls just slightly different than our own, but not by much. By measuring total cranial volume, paleontologists noticed that Neanderthals and humans shared similar brain volume, so they figured that the internal organization was probably the same.

But this is not the case, say Eiluned Pearce, Chris Stringer, and R. I. M. Dunbar, who argue that Neanderthals had a different visual system — one that, along with greater body mass, resulted in smaller endocranial capacities compared to humans.

In other words, Neanderthals dedicated so much power to their visual systems that their high-level processing was compromised. This prevented them from developing complex social networks, which may have resulted in their inability to thrive.

The BBC elaborates:

The research team explored the idea that the ancestor of Neanderthals left Africa and had to adapt to the longer, darker nights and murkier days of Europe. The result was that Neanderthals evolved larger eyes and a much larger visual processing area at the back of their brains.

The humans that stayed in Africa, on the other hand, continued to enjoy bright and beautiful days and so had no need for such an adaption. Instead, these people, our ancestors, evolved their frontal lobes, associated with higher level thinking, before they spread across the globe.

And because Neanderthals evolved at higher latitudes, more of their brain would have been dedicated to vision and body control, leaving less brain to deal with other functions like social networking. As the authors note in their study, this may have affected their “abilities to cope with fluctuating resources and cultural maintenance.”

Check out the entire study at the Proceedings of the Royal Society B.

Image: NHM.