Scientists used computer imaging to discover why Neanderthals went extinct

Ever since a paleontologist discovered the first skeleton Homo neanderthalensis in 1829, scientists have tried to reconstruct why Homo sapiens finally prospered, while the Neanderthals disappeared about 40,000 years ago. [19659002] When comparing their prehistoric skulls with ours, scientists discovered that the Neanderthal brains were a little larger than ours, both at birth and large, and that they may have lived longer than our ancestors. So, why did not this evolutionary advantage help Neandertals to dominate humanity?

Using biomedical imaging software and Neanderthal skull fossils, three Japanese researchers have now traced how specific portions of Neanderthal brains compared to ancient humans, and how specialized parts of The brains of Homo sapiens they may have contributed to their survival over the Neanderthals.

Published in Scientific Reports (SR) earlier this month, "Reconstructing Neanderthal brain using computational anatomy" revealed that the cerebellums of our ancestors were significantly larger than the ancient Neanderthals " .

And the researchers theorize that the larger cerebellums of humans gave them "superior cognitive and social functions, including executive functions, language processing, and episodic and working memory capacity."

Researchers combined brain Neanderthal (a) models with modern human scans (b) to label theoretical parts of the Neanderthal brain (c) | Credit: Kochiyama et al.

Due to their supposedly inferior In terms of communication and long-term memory, Neanderthals may have had more problems adapting to climate change events such as the glaciations that Homo sapiens .

To reach this conclusion, the researchers scanned 1,185 healthy human brains, then compared them to the fossilized skulls of four ancient Homo sapiens and four Neandertals. They then created virtual 3D "molds" of the skulls and compared them with modern brain scans to determine how they might have looked when they were still alive.

  The displacement of form between primitive humans and Neanderthals showed that our brains were more different on the right side, where the cerebellum rests | Credit Kochiyama et al.

The displacement of form between primitive humans and Neanderthals showed how our brains differ mainly on the right side, where the cerebellum rests | Credit Kochiyama et al.

A previous study 2013 theorized that the brains of the Neandertals devoted more cognitive power to better vision and motor control, and suggested that further thinking might have been damaged as a result.

But as the co-author of SR Naomichi Ogihara said Scientific American they are the first to digitally reconstruct Neanderthal brains.

"Our method allows us to estimate the shape and volume of each region of the brain, which is completely impossible simply by analyzing the endocranial surfaces."

Once inside these prehistoric brains, Ogihara and his colleagues were surprised by their findings "Initially we expected that the frontal lobe would be different between the two species because it was considered to be related to higher cognitive functions, but it was not the case."

In contrast, although our frontal lobes seemed almost equal, our cerebellums had significantly more cognitive power. This region helps coordinate cognitive processes in different parts of the brain in the correct order, and our larger cerebellums increased our processing capacity.

Basically, we were lucky in a better CPU and the Neanderthals simply could not keep up.

Robin Dunbar, an evolutionary psychologist who spoke with Scientific American about the research, emphasized that this research does not prove that Neandertals were "less human or more unstable men-men." On the other hand, the difference would have been subtle; but as Ogihara said, subtle differences "may become significant in terms of natural selection."

One theory among many

Although this research presents a convincing case, other scientists have intervened to point out some flaws in the analysis.

We know that Neandertals became extinct, but it is not yet clear if their small cerebellum was a primary factor, compared to many other possible causes of extinction.

Lana Ruck, a Ph.D. student in cognitive science at Indiana University, said Gizmodo that healthy humans tend to have different sizes in cerebellum, and that this deviation does not necessarily correspond to inferior executive functions or memory in contemporary humans.

And neuroscientist at the University of Washington Kari L. Allen stated that while SR study "rel [ies] with the premise that the big is better and that the shape of the brain surface can be used to interpret the size of the brain components, "Conventional neuroscience can not support your beliefs.

In fact, Allen says, "the general form of the brain is almost certainly a multi-factor compromise and some of them probably have a small impact on cognition."

Therefore, although this study could lead to an influx of research on digital re-creations of ancient human brains, it is not yet clear how much this research can actually tell us.

Via Scientific American