Scientists link autism traits to Neanderthal DNA in humans

With the continuous advancements in science, we keep learning new things about ourselves and our ancestry, including the DNA link between neurodivergence and an unexpected relative to today’s humans – the Neanderthals.

As it happens, a shocking discovery has recently uncovered that some of the genetic variants humans have inherited from Neanderthals might have a connection to autism spectrum disorder, according to a report by Earth.com published on July 7.

Indeed, small groups of modern humans bred with Neanderthals as they met them while trekking out of Africa into Eurasia around 50,000 to 60,000 years ago, thus exchanging genes, and researchers believed that Eurasian-derived populations have about 2% Neanderthal DNA.

After that, as some of their descendants traveled back to Africa, they brought a little more Neanderthal genes across the continent, all of which has led to almost every person on Earth carrying at least a trace of Neanderthal ancestry, in various amounts.

Autism traits and Neanderthal DNA

In terms of autism and its connection to Neanderthal DNA, researchers from Clemson University and Loyola University have carried out a study that compared whole-genome data from autistic people, their unaffected siblings, and unrelated controls across diverse ethnic backgrounds.

What they noticed was significant – both rate and common Neanderthal-derived variants appeared more often in autistic participants. That said, it wasn’t much about the quantity of the present Neanderthal DNA, but rather the particular snippets of it, like genes that guide how distant brain regions communicate with each other.

For instance, visual-processing circuits would run hotter, while the default mode network, linked to daydreaming and social reflection, would run cooler, signifying keen pattern recognition and social fatigue and matching these signatures to traits often present in autistic individuals.

The findings were further confirmed through functional MRI, and people with a higher amount of identified Neanderthal variants – autistic or not – demonstrated stronger signaling in visual-processing areas. At the same time, pathways activated during casual conversation or idle thought remained quieter.

As such, these ancient genes seem to be part of a cognitive profile benefitting intense observation and precise motor planning, as in Neanderthal craftsmanship and stone tool-making skills, as well as required for visual scouting for game, shelter, or resources, outweighing complex social interactions – resonating with strengths and weaknesses of many autistic individuals.

Elsewhere, researchers have discovered another groundbreaking thing about our human relatives – extinct hominins called Denisovans – suggesting that they lived throughout East Asia, from Siberia to the Tropics, for hundreds of years – something not even the robust Neanderthals have accomplished.