Got a Brawny Build? You Might Be Able to Thank Your Neanderthal Ancestors, According to a New Study

Neanderthals once roamed the lands of Europe and Asia for over 400,000 years before eventually disappearing. As they did, some of them bred with early humans, leaving a genetic footprint in our ancestry. Today, nearly all non-African people carry between 1 and 4 percent of Neanderthal DNA. A new study published in Current Biology suggests that this Neanderthal genetic material could be linked to certain physical traits in contemporary humans.

Researchers focused on the human growth hormone pathway, which starts when the pituitary gland releases hormones into the bloodstream, which then bind to cell surfaces in muscles and bones to signal growth. Variations in this pathway could influence a person's height and muscle mass. Specifically, the team identified two DNA variants in a gene encoding the growth hormone receptor that were more common in today's non-European populations.

These particular alleles appeared to be particularly prevalent in South and East Asia, with up to 24 percent of individuals in some populations carrying them. Europeans, on the other hand, showed the variant in only 0.5 percent of their DNA, while Indigenous Americans carried it in just 2 percent of their genomes. This distribution challenges the notion that Neanderthals were exclusively European in appearance.

The findings also indicate that modern humans with the Neanderthal variant are, on average, 0.12 inches taller and 0.6 pounds heavier than those without the variant. Even more intriguing, the study found that these individuals possess subtle Neanderthal-like traits, such as shorter tooth roots and a smaller ramus in their rear jawbone.

To further test the impact of the gene variant, the researchers grew cultured cells with either the Neanderthal or modern human variant and exposed them to growth hormones. Cells carrying the Neanderthal variant proliferated nearly 40 percent more over five days than those with the modern human variant. These findings suggest that the Neanderthal gene variant may have played a role in shaping the distinctive physical characteristics of our extinct relatives and could still be influencing the builds of some modern humans today.

However, the researchers emphasize that this variant is just one piece of a complex genetic puzzle, and numerous other genes contribute to growth and body shape.