Some modern humans may owe their larger body size and greater muscle mass in part to a growth hormone receptor inherited from Neanderthals, according to new research. Scientists say the genetic variant was passed to our ancestors through interbreeding between modern humans and Neanderthals roughly 47,000 years ago.
The researchers revealed their findings in a recent paper published in the journal Current Biology, identifying the Neanderthal growth hormone receptor as present primarily in southeast asian populations.
Along with its primary findings, the new study is notable for the convergence of two independent lines of evidence: laboratory experiments and real-world population data.
Neanderthal Muscles
Although we have no living Neanderthals to examine, scientists can draw certain conclusions about their physical appearance from skeletal remains. Their bones indicate that these archaic humans were powerfully built, with substantial muscle mass. Their skulls also commonly display features such as shallow tooth roots and prominent brow ridges.
Despite their physical strength, Neanderthals eventually disappeared around 42,000 years ago.
The researchers set out to study lingering elements of Neanderthal ancestry in modern humans, specifically the effects of a Neanderthal-derived growth hormone receptor. Although Neanderthals once ranged across Europe and Asia, the team found that the genetic variant they were studying is concentrated primarily in one region.
The highest prevalence of the Neanderthal growth hormone receptor was found in parts of South Asia, where approximately 24% of people in some populations carry it. By comparison, only about 0.5% of Europeans carry the variant.
Growth Hormone
Growth hormone is produced by the pituitary gland in the brain and released into the bloodstream, eventually reaching tissues including muscles and bones. There, it binds to receptors on the surfaces of cells, triggering signals that promote cell proliferation and help regulate tissue and bone growth.
To test the Neanderthal growth hormone receptor, the researchers introduced it into human cells grown in the laboratory. Cells carrying the Neanderthal variant subsequently demonstrated a 40% increase in cell proliferation compared with cells carrying a common modern human version of the receptor.
The team found evidence for the receptor’s influence on muscle growth not only in laboratory experiments but also in real-world population data. On average, carriers of the Neanderthal-derived variant had approximately 270 additional grams of muscle mass.
“What struck me most was that two very different types of evidence told the same story,” said first author Philipp Kanis, a postdoctoral researcher at the Max Planck Institute for Evolutionary Anthropology. “Cells grown in the laboratory responded more strongly, while data from more than a million people showed signs of the same effect in the body. It is rare to see laboratory and population evidence fit together so clearly.”
Continuing Neanderthal Influence
The differences did not end with muscle mass. Carriers of the Neanderthal-derived variant also tended to have shorter tooth roots and differences in jaw shape associated with their Neanderthal ancestry. The researchers say the physical effects associated with the receptor likely emerge only after age 11, noting that the significant increase in growth hormone levels during puberty may help drive these changes.
“As someone who does CrossFit, I was delighted to find Neandertal genetics and muscle mass coming together in the same study,” commented co-author Miriam Berreiter. “But even a Neandertal growth hormone receptor is no substitute for training.”
“It is fascinating that one genetic change inherited from Neandertals can still have an effect on the human body today,” concluded senior author Hugo Zeberg. “But this is only one of many genetic influences on growth and body shape. It cannot explain the Neandertal body type on its own, and it certainly does not determine a person’s overall appearance.”
The paper, “Increased Signaling of the Neanderthal Growth Hormone Receptor,” appeared in Current Biology on August 5, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org.