Neanderthals were similar to us, almost genetically identical, but they looked quite different. With their strong jaws, big noses, and pronounced brows, Neanderthal faces distinguished them from modern humans. These unique features come from minor changes in a part of our DNA known as the “dark genome.”
Often called “junk DNA,” the dark genome doesn’t contain genes but includes instructions that help manage and regulate gene activity. About 98% of our DNA falls into this category. Recent studies suggest that a specific region in this dark genome influences the facial characteristics of Neanderthals versus modern humans.
Dr. Hannah Long, a study author, explained, “The Neanderthal genome is 99.7% identical to modern humans. The few differences likely shape their appearance.”
To pinpoint where these differences lie, researchers examined a region called enhancer cluster 1.45 (EC 1.45). This area regulates the SOX9 gene, which plays a role in facial development. Certain changes in this region are linked to conditions like Pierre Robin sequence, which affects jaw formation.
When scientists compared the EC 1.45 versions of Neanderthals and humans, they found just three letter differences. They inserted these versions into zebrafish DNA to observe changes in developing embryos. Surprisingly, the Neanderthal version was more active, indicating that their SOX9 gene would have been more strongly expressed during development.
This increased activity likely contributed to the distinct jaw shapes seen in Neanderthals. In fact, when researchers added extra copies of the SOX9 gene to zebrafish, the results showed larger jaws, supporting the connection between the gene and facial structure.
Dr. Long mentioned the potential applications of this research. “We hope this helps advance our understanding of genetic changes in people with facial conditions,” she said.
This study provides not only a glimpse into our ancient relatives but also opens doors to understanding genetic factors in modern health. For further details, you can read the full study published in the journal Development here.
