“We are Far from Understanding the Brain of Prehistoric Humans” –Neanderthals Reveal Subtle Clues

 

Homo_sapiens_neanderthalensis

 

Scientists have for the first time set eyes on a three-dimensional Neanderthal brain in the form of a virtual model made to fit the empty, fossilized skulls of long-dead individuals, a study said Thursday. The reconstructed organ confirmed earlier observations, based more loosely on head size and shape, that Neanderthals had a larger brain than their early Homo sapiens cousins, but with a smaller cerebellum—the lower part near the spine that controls balance and movement. It is also involved in speech and learning.


“This was surprising since the cerebellum is traditionally considered important for motor-related functions, says Naomichi Ogihara of the Keio University in Japan. “We initially expected that the frontal lobe would be different between the two species because it has been considered to be related to higher cognitive functions, but it was not the case.”

 

The distinction may have caused social and cognitive differences between the near relatives, and may explain why one went extinct while the other thrived, said Ogihara who co-authored a study in the journal Scientific Reports. "Although the difference could be subtle, such a subtle difference may become significant in terms of natural selection," he told AFP.

“The paper gives the impression the cerebellum is intimately involved in a large number of higher cognitive functions, says evolutionary psychologist Robin Dunbar of the University of Oxford in England who was not involved in the work. “This isn’t strictly true—its function seems to be rather one of coordination between different brain units and cognitive procesings—in effect, making sure computations are done in the right order. That role is almost certainly crucial to higher cognitive functions and allows us to do what we do,” he told Scientific American. One reason for the importance of cerebellum volume, the authors suggest, is that unlike other regions it consists of a large array of identical processing units, so larger volumes logically equate to higher processing capacity.

“Deforming a modern brain into a Neandertal one may obscure changes specific to the two lineages,” says paleoneurologist Emiliano Bruner of the National Research Center for Human Evolution in Spain who was not involved in the study after Neandertals split from humans on the evolutionary tree. “After their separation, the Neandertal and modern lineages could have undergone some specific changes that cannot be detected by this method.” The authors reason, however, that since chimpanzee and bonobo brains can be morphed into each other, and they diverged around two million years ago, the approach is a reasonable one, because Neandertals more recently diverged from humans some 700,000 years ago.

But nothing can be concluded yet about any relation between the Neanderthal's brain organisation and its eventual demise. Ogihara and a team combined the disciplines of physical anthropology, mechanical engineering, and neuroscience for their reconstruction. They used virtual casts to model the shape and size of four fossilised Neanderthal skull cavities, and four of ancient humans.

They then used MRI scans from nearly 1,200 modern-day people to model an "average" human brain, which they "deformed" to fit into the prehistoric skulls. This allowed the team to estimate what the brains would have looked like, and how individual regions would have differed between the two species.

"We are so far from understanding the brain of prehistoric humans that any small advance is welcome," French palaeoanthropologist Antoine Balzeau told AFP of the study. He was not involved in the research.

Neanderthals emerged in Europe, Central Asia and the Middle East some 200,000 years ago. They vanished about 30,000 years ago—coinciding roughly with the arrival of modern humans out of Africa.

The two groups briefly overlapped and interbred, and today, non-African people carry about 1.5-2.1 percent of Neanderthal DNA.

Long portrayed as knuckle-dragging brutes, recent studies have started to paint a picture of Neanderthals as sophisticated beings who made art, took care of the elderly, buried their dead, and may have been the first jewelers—though they were probably also cannibals.

The Daily Galaxy via AFP and Scientific American

Image credit: Wikipedia

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