Every face tells a story, and scientists are now tracing that story back to our ancient relatives. Researchers at the MRC Human Genetics Unit in the Institute of Genetics and Cancer at the University of Edinburgh, UK, have found clues in Neanderthal DNA that could explain how facial shapes evolved. The study, published in the journal Development, shows that a stretch of Neanderthal DNA is more active in turning on a key jaw-forming gene than the modern human version — offering one possible reason for Neanderthals’ stronger, larger jaws.
How Does Neanderthal DNA Differ from Ours?
Neanderthals, who lived tens of thousands of years ago, had distinct facial features with large noses, pronounced brows and robust jaws. Scientists have sequenced their genome using DNA from ancient bones, revealing that it is 99.7% identical to modern human DNA. According to Hannah Long, who led the study, the small genetic differences between humans and Neanderthals may have shaped how their faces looked.
“Our genomes contain around three billion letters, so finding the ones that affect appearance is like finding a needle in a haystack,” Long explained. Her team focused on a region of DNA linked to Pierre Robin sequence, a condition where the lower jaw is unusually small. “Some people with this condition have deletions in this part of the genome,” Long said. “We predicted that smaller differences might subtly influence face shape.”
What Did the Experiments Show?
By comparing the human and Neanderthal genomes, the researchers discovered only three single-letter differences in a short DNA segment about 3,000 letters long. Although this region does not contain any genes, it controls the activity of a nearby gene called SOX9, which coordinates facial development.
To see how these differences affect development, the team inserted both the Neanderthal and human DNA versions into zebrafish embryos. The fish were engineered to glow in different colours when the respective DNA regions were active. As the embryos developed, both versions lit up in cells that form the lower jaw — but the Neanderthal version glowed more strongly.
“It was very exciting to see activity near the developing jaw,” Long said. “Even more so when we realised the Neanderthal version worked more powerfully.” When the team gave the zebrafish extra SOX9, the cells forming the jaw spread across a larger area, suggesting that the boosted activity could produce a bigger jaw, similar to what is seen in Neanderthals.
Why Does This Matter for Understanding Human Faces?
Long’s team believes this discovery could reveal how tiny DNA changes influence the structure of the face. “We are now exploring other genetic differences using lab techniques that mimic facial development in a dish,” she said. The aim is to understand how certain DNA sequences may affect people with facial conditions and improve genetic diagnosis.
The researchers say that studying extinct species like Neanderthals helps reveal how modern human faces evolved and why each face is unique. Their findings link ancient DNA to living biology, offering new insights into the long evolutionary story written in our genes.
(Source: Development, University of Edinburgh – https://journals.biologists.com/dev/article-lookup/DOI/10.1242/dev.204779)
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