When our ancient human ancestors migrated out of Africa, they came across their own evolutionary cousins, Neanderthals, who made the journey thousands of years before. Thanks to some prehistoric canoodling, many of us still carry around bits of Neanderthal DNA in our genome.
As previous studies have suggested, one of the strangest relics of this legacy could actually be certain mental health conditions. For the first time, scientists at the National Institute of Mental Health (NIHM) have gathered evidence that supports the possibility that Neanderthal genes affect the structure of modern-day human brains. Their research was published this week in the journal Scientific Reports.
Neanderthal gene variants probably cropped up in humans somewhere in Eurasia between 47,000 and 65,000 years ago, the study says. In total, the Neanderthal genes only account for about 2 percent of the entire non-African human genome. However, how it affects modern humans is still not fully understood.
The researchers used MRI scans to measure the physical structure of the brain in 221 people of European ancestry from the NIMH Genetic Study of Schizophrenia. Those who were shown to have a higher concentration of Neanderthal-derived genetic variants also had skull shapes that more greatly resembled Neanderthals, particularly in relation to the occipital and parietal bones. This suggests that Neanderthal-derived genes are involved in the development of the brain’s visual system in modern-day humans.
Fossilized skulls of Neanderthals indicate they had a more prominent visual system than modern humans. Understandably, this was pretty useful for tasks such as tool-making and locating objects, but the theory goes that these Neanderthal-derived gene variants led to a visuospatial prowess that forced a trade-off for the part our social brain. This could be a possible link between Neanderthals and certain mental health conditions in modern humans.
“It’s been proposed that Neanderthals depended on visual-spatial abilities and toolmaking, for survival, more so than on the social affiliation and group activities that typify the success of modern humans – and that Neanderthal brains evolved to preferentially support these visuospatial functions,” Dr Michael Gregory Berman of the NIMH Section on Integrative Neuroimaging said in a statement. “Now we have direct neuroimaging evidence that such trade-offs may still be operative in our brains.”
