Researchers have identified a genetic variant inherited from Neanderthals that contributes to increased muscle mass and certain physical traits in modern humans. This discovery sheds light on how Neanderthal DNA, assimilated into the human genome through interbreeding tens of thousands of years ago, continues to influence human biology.
The study, conducted by an international team from institutions including the Wellcome Sanger Institute in the UK and the Max Planck Institute for Evolutionary Anthropology in Germany, analyzed genetic and biometric data from more than 113 million individuals across multiple biobanks. Their findings indicate that carriers of this Neanderthal-derived variant, which affects a growth hormone receptor (GHR) protein, exhibit approximately 270 to 285 grams more lean muscle mass on average compared to those without the variant. The variant also correlates with slightly increased height—about 3 millimeters taller—and a wider hip circumference.
This growth hormone receptor variant is present in varying frequencies among global populations: around 0.5 percent of Europeans, 2 percent of North and South Americans, 15 percent of East Asians, and 20 percent of South Asians carry the Neanderthal version. The receptor, located on the surface of cells, interacts with the body’s growth hormone to regulate development.
Beyond muscle mass and stature, the research identified subtle morphological changes associated with the variant. These include shorter tooth roots, modifications in jaw shape—specifically a shorter vertical section of the lower jaw called the ramus—and a slightly increased risk of overbite. Notably, these physical features were observed only in individuals who had gone through puberty, suggesting the genetic effects manifest later in development.
Laboratory tests reinforced these observations, with cultured cells expressing the Neanderthal receptor demonstrating a 40 percent increase in growth compared to those with the modern human receptor. "It is rare to see laboratory and population evidence fit together so clearly," said Philipp Kanis, lead author of the study.
The persistence of Neanderthal DNA in modern humans is the result of interbreeding between Neanderthals and early Homo sapiens roughly 40,000 years ago. Although Neanderthals vanished as a distinct group, their genetic legacy survives, comprising about 2 percent of the genome in non-African populations. This challenges earlier views that Neanderthals were simply outcompeted or less intelligent, highlighting instead the complexity of interactions between the two species.
Miriam Berreiter of the Karolinska Institute, a co-author of the study, emphasized that despite the genetic influence on muscle growth, physical training remains essential. “Even a Neanderthal growth hormone receptor is no substitute for training,” she noted.
The research, published in the journal Current Biology, illustrates how remnants of ancient human relatives continue to shape aspects of modern human physiology, emphasizing a nuanced understanding of human evolution and genetic diversity.