A genetic variant inherited from Neanderthals has been linked to increased muscle mass and certain physical traits in modern humans, according to new research involving over a million participants. The study, conducted by an international team of scientists from institutions including the Wellcome Sanger Institute in the United Kingdom and the Karolinska Institute in Sweden, examined the prevalence and effects of a Neanderthal-derived growth hormone receptor gene variant.
Researchers analysed genetic and biometric data from 1.13 million adults across five biobanks, as well as data from 6,602 children in Bradford, England, a population with significant South Asian heritage. They found that individuals carrying this specific variant of the growth hormone receptor (GHR), which occurs in roughly 0.5% of Europeans, 2% of North and South Americans, 15% of East Asians, and 20% of South Asians, tend to be taller and possess greater lean muscle mass compared with those without the variant.
On average, carriers of the Neanderthal receptor gene stood about 3 millimeters taller and had between 270 and 285 grams of additional weight attributed almost entirely to muscle rather than fat. This increased muscle bulk was observed predominantly in the arms, legs, and torso. The study also identified subtle differences in body composition, including a hip circumference on average 2.7 millimeters wider.
In addition to musculoskeletal differences, the researchers noted variations in dental and jaw structure. Carriers exhibited shorter tooth roots and a distinct shape of the jawbone, specifically a shorter ramus—the vertical part at the back of the lower jaw—which correlated with a higher likelihood of overbite. Notably, these anatomical changes were not observed in the cohort of children, suggesting the effects may manifest later in development or adulthood.
The Neanderthal version of the GHR protein differs from the Homo sapiens variant by two amino acid substitutions, which scientists believe influence how it interacts with growth hormone to affect physical development. Miriam Berreiter of the Karolinska Institute, lead author of the study, cautioned that despite the genetic influence on muscle mass, individuals still require physical training to develop strength. “Even a Neanderthal growth hormone receptor is no substitute for training,” she said.
The findings shed light on how interbreeding between early modern humans and Neanderthals—who lived until approximately 40,000 years ago—has left a lasting genetic legacy. While Neanderthals were once thought to have disappeared due to cognitive inferiority, recent research suggests they were genetically and anatomically similar to Homo sapiens, and their DNA persists in about 2% of the genome of people outside sub-Saharan Africa.
This study adds to growing evidence that traits once unique to Neanderthals continue to influence aspects of human biology today, particularly in populations with higher frequencies of the variant.