Neanderthal growth hormone variant increases muscle mass in modern human carriers
A study finds that ancient DNA variants in the growth hormone receptor gene make carriers taller and more muscular, with the Neanderthal-derived version most common in South and East Asian populations.
Some of the genetic variation that shapes human bodies today was inherited from populations that went extinct tens of thousands of years ago. A study published in Current Biology has traced two specific changes in the growth hormone receptor gene back to Neanderthal genomes, and found that modern humans who carry these variants are measurably taller and more muscular than those who don’t.
The research, led by Philipp Kanis at the Max Planck Institute, focused on how these ancient DNA sequences alter the function of a receptor that responds to growth hormone. In laboratory tests, cells carrying the Neanderthal-derived receptor proliferated around 39% more over five days than cells with the modern human variant, and produced more STAT5 signaling protein when exposed to growth hormone. The effect translates into modest but detectable differences in people: carriers of the Neanderthal variant were on average 0.3 centimetres taller and had 0.25 kilograms more muscle mass.
The variant is not evenly distributed across human populations. It reaches its highest frequency in South and East Asia, at about 24% in Pakistan, and declines in frequency toward Europe and Africa. This geographic pattern reflects the complex history of interbreeding between anatomically modern humans and Neanderthals, which occurred primarily in Eurasia after modern humans left Africa.
The same genetic changes appear to influence more than just stature and muscle. The study also links the Neanderthal-derived variant to specific facial traits: carriers tend to have a shorter lower jaw, a higher chance of overbite, and shorter tooth roots. These correlations suggest the growth hormone receptor affects craniofacial development in ways that were likely visible in Neanderthal populations themselves.
The findings add to a growing picture of how archaic human DNA persists in modern genomes and continues to influence physiology. Previous studies have connected Neanderthal variants to immune function, skin pigmentation, and risk for certain diseases. The growth hormone receptor joins that list as a case where the archaic version appears to confer a straightforward physical advantage—greater muscle mass—without obvious tradeoffs severe enough to have eliminated it through natural selection.
Whether the variant offers any functional benefit in contemporary environments is unclear. The differences in height and muscle mass are small enough to be swamped by nutrition, training, and other genetic factors. But the result demonstrates that some of the genetic architecture of human bodies was laid down by populations that disappeared from the fossil record while leaving fragments of themselves scattered through the genomes of their descendants.