Neanderthal Gene Variant May Influence Height, Muscle Mass and Jaw Development Today

Although Neanderthals disappeared about 42,000 years ago, a genetic variant inherited from them may still influence body size, muscle development and facial structure in some modern humans, according to a new study led by researchers at the Max Planck Institute for Evolutionary Anthropology.

Neanderthals are among the best-known archaic human groups. They first appeared in the fossil record approximately 300,000 to 400,000 years ago and lived across Europe and western Asia before becoming extinct around 42,000 years ago.

Compared with modern humans, Neanderthals generally had more robust bodies, larger brains, prominent brow ridges, an occipital bun at the back of the skull, barrel-shaped chests, greater muscle mass and short-rooted teeth, a condition known as taurodontism.

While none of these features was exclusive to Neanderthals, their combination helped distinguish the group as a separate evolutionary lineage. Genetic evidence later showed that Neanderthals evolved largely apart from modern humans for roughly half a million years.

However, the two groups did encounter and interbreed with one another. As a result, people with ancestry outside Africa typically carry about 2% Neanderthal DNA. The primary Neanderthal-modern human admixture event is thought to have occurred approximately 47,000 years ago, although earlier episodes of gene flow may also have taken place.

To investigate the genetic factors behind the Neanderthal body structure, Dr. Philipp Kanis, a postdoctoral researcher at the Max Planck Institute for Evolutionary Anthropology, and his colleagues focused on the growth hormone receptor.

This receptor helps cells respond to growth hormone, a chemical messenger produced by the pituitary gland that plays an important role in growth, development and body composition.

By comparing modern human DNA with high-quality Neanderthal genomes, the scientists identified a distinctive Neanderthal version of the growth hormone receptor. The variant contains two amino acid changes that are not found in present-day African populations.

The researchers then introduced the Neanderthal receptor variant into laboratory-grown cells. After exposing the cells to growth hormone, they found that cells carrying the Neanderthal version multiplied more quickly and produced stronger downstream signaling than cells with the modern human receptor.

Because Neanderthals interbred with the ancestors of modern non-African populations, the receptor variant was passed down through generations. It is most common in parts of South and East Asia, where it occurs in approximately one-fifth of some populations, but it is rare or absent in sub-Saharan Africa.

The geographic distribution of the variant is consistent with the history of Neanderthal ancestry in modern human populations.

To determine whether the genetic variant affects people today, the team analyzed genetic, medical and health information from more than one million individuals included in several biobanks.

Adults carrying the Neanderthal growth hormone receptor variant tended to be slightly taller and heavier than non-carriers. The additional body weight appeared to be linked mainly to increased muscle mass rather than higher levels of body fat.

Carriers also showed several skeletal and dental characteristics associated with Neanderthals, including a shorter mandibular ramus, a greater likelihood of overbite and somewhat shorter tooth roots.

These differences were not observed in children. The researchers suggest that the effects may become apparent around puberty, when growth hormone production increases significantly.

“The most striking finding was that two independent lines of evidence pointed to the same biological effect,” Dr. Kanis said.

“Laboratory cells showed stronger growth hormone responses, while data from more than one million people revealed related differences in body size and skeletal traits.”

Dr. Hugo Zeberg, also from the Max Planck Institute for Evolutionary Anthropology, said the study demonstrates how a genetic change inherited from Neanderthals can continue to influence human biology thousands of years after the group’s extinction.

However, the researchers emphasized that the variant represents only one of many genetic factors involved in height, muscle mass, growth and body shape. It cannot independently account for the complete Neanderthal physique or determine a person’s overall appearance.

The team’s study was published in the journal Current Biology.

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Philipp Kanis et al. Increased signaling of the Neanderthal growth hormone receptor. Current Biology, published online August 5, 2026; doi: 10.1016/j.cub.2026.07.025