Scientists link autism to Neanderthal DNA found in modern humans

When folks picture Neanderthals, the image often involves heavy brows, furry pelts, and stone tools. Yet pieces of their DNA are still part of the modern human genome. Recent research suggests that some of these genetic variants inherited from Neanderthals could be linked to autism spectrum disorder.

About 50,000-60,000 years ago, small groups of modern humans trekked out of Africa into Eurasia. They met Neanderthals, exchanged tools, and also exchanged genes through interbreeding.

It has been estimated that Eurasian-derived populations have approximately 2% Neanderthal DNA, which was acquired during introgression events occurring shortly after anatomically modern humans migrated out of Africa.

Later, some descendants journeyed back to Africa, sprinkling a much thinner dusting of Neanderthal genes across the continent.

That genetic shuffling means nearly everyone on Earth carries at least a trace of Neanderthal ancestry, though the amount varies.

Small fragments, big questions

Genetic leftovers can be helpful. Certain Neanderthal alleles boost immune responses or aid survival at high altitudes.

Many others never meshed well with our biology and were slowly weeded out by natural selection. Brain-related genes are especially unforgiving; even minor glitches can prove disruptive.

With the recent sequencing of multiple archaic human genomes, there has been growing interest concerning the influence of archaic human-derived alleles on modern health.

Yet some Neanderthal variants slipped past that filter. They linger in regions tied to perception, memory, and social understanding, sparking curiosity about their subtle effects.

Autism clues in Neanderthal DNA

The study linking autism to Neanderthal DNA was led by researchers from Clemson University and Loyola University.

The authors compared whole-genome data from autistic people, their unaffected siblings, and unrelated controls across diverse ethnic backgrounds.

They saw that both rare and common Neanderthal-derived variants appeared more often in autistic participants.

The pattern wasn’t about carrying more Neanderthal DNA overall; it hinged on possessing particular snippets.

One striking theme involved genes that guide how distant brain regions talk to each other.

Visual-processing circuits appeared to run hotter, while the so-called default mode network, linked to daydreaming and social reflection, ran cooler.

Those connectivity signatures match traits many autistic individuals report – keen pattern recognition alongside social fatigue.

Seeing the world in sharp focus

Functional MRI scans from the same project confirmed this pattern. People who carried a higher load of the identified Neanderthal variants – whether autistic or not – showed stronger signaling in visual areas.

Meanwhile, pathways that normally hum during casual conversation or idle thought stayed quieter.

The result hints that these ancient genes might sculpt a cognitive profile tuned for intense observation and precise motor planning.

Archaeologists note a similar nuance in Neanderthal craftsmanship and stone tool making skills.

Their Levallois technique required stepwise planning, spatial reasoning, and sustained focus – skills that resonate with strengths many autistic thinkers display today.

An evolutionary twist

Why would such variants stick around? One idea points to the small, tight-knit bands Neanderthals likely formed. In that setting, visual scouting for game, shelter, or stone resources could outweigh complex social juggling.

When Homo sapiens groups interbred with them, those advantageous perceptual talents may have proved useful enough to persist.

The study does not argue that Neanderthal DNA “causes” autism. Instead, it suggests that a handful of inherited tweaks can raise the odds of certain traits emerging along a spectrum.

Those traits might have offered benefits in ancestral environments – and still do in fields that prize logic, detail, and pattern spotting.

Neanderthal contributions to autism

Researchers stress that genetics is only part of the autism puzzle. Environment, early development, and countless other genes interact in ways science is still charting.

Even so, identifying concrete Neanderthal contributions helps explain why autism exists worldwide, independent of culture or upbringing.

It also reframes neurodiversity as a legacy of humanity’s mixed heritage rather than a modern anomaly.

Many families notice clusters of analytical talent – mathematicians, engineers, visual artists – scattered among autistic and non-autistic relatives alike. The new findings offer a biological thread connecting those shared gifts.

What happens next?

“We hope this research will lead to further investigation into the ongoing influences of ancient hybridization between Homo sapiens and Neanderthals in brain development, human intelligence, and overall human health, as well as spur work into additional clinical resources for this complex population,” the research team wrote.

Future projects will likely probe other neurodevelopmental conditions, explore how Neanderthal variants interact with modern lifestyles, and refine personalized supports.

As we continue to discover, the story of human evolution didn’t stop with one lineage replacing another. It wove their strengths together, leaving fingerprints that guide our thoughts, perceptions, and innovations in modern humans to this day.

The full study was published in the journal Molecular Psychiatry.

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