Study Links Neanderthal Growth Hormone Receptor Variant to Greater Muscle Mass in Modern Humans

A study published in Current Biology links a Neanderthal version of the "growth hormone receptor" to enhanced muscle growth in modern humans, with the findings reported as published on the 5th (local time) in the international journal Current Biology.

“The findings were published on the 5th (local time) in the international journal Current Biology.”

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The research team led by the Max Planck Institute for Evolutionary Anthropology in Germany and the Karolinska Institute in Sweden found that after five days, the number of cells with the Neanderthal receptor was 39% higher when exposed to the same concentration of pituitary growth hormone.

Karolinska Institutet

To test whether the cellular effect persisted in people, the researchers analyzed genetic and physical data from 1.1342 million adults registered in biobanks in the UK, Finland, Japan, South Korea, and Taiwan.

Individuals who inherited one copy of the Neanderthal growth hormone receptor variant from either parent were, on average, 3 mm taller and 285 grams heavier than those without the variant, with the weight difference largely due to 150 grams of additional limb muscle mass and 121 grams of lean body mass (excluding fat).

The variant’s effects also extended to jaw and teeth, with a review of four previous studies showing carriers had a 3.6 mm shorter "mandibular angle" and a small-scale study in Japan reporting shorter roots in some front teeth and upper canines.

Karolinska Institutet researchers said the Neanderthal variant is found mainly in South and East Asia and, in some populations there, is carried by up to 24 per cent of people.

In laboratory experiments described by Karolinska Institutet, cells carrying the Neanderthal variant grew 40 per cent more than cells with the most common modern human version of the receptor when stimulated with growth hormone.

Max-Planck-Gesellschaft

Hugo Zeberg, who led the study and is a senior lecturer at the Department of Physiology and Pharmacology, Karolinska Institutet, said, "It is fascinating that a gene variant inherited from Neanderthals still affects people today."

Co-author Miriam Berreiter, who said she does CrossFit, added, "But even a Neanderthal growth hormone receptor can replace training."

The study also reported that no effect was seen in more than 6,000 children aged 11 or younger, suggesting the difference may emerge later, possibly during puberty, when growth hormone levels rise.

The study’s authors emphasized that the Neanderthal growth hormone receptor variant is only one factor shaping growth and body shape, and that it cannot explain the Neanderthal body type on its own.

“"It is fascinating that one genetic change inherited from Neandertals can still have an effect on the human body today"”

Phys.org

Hugo Zeberg said, "But this is only one of many genetic influences on growth and body shape," and that it "cannot explain the Neanderthal body type on its own, and it certainly does not determine a person’s overall appearance."

Philipp Kanis described the study as rare because it connected laboratory and population evidence, saying, "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."

The Discover Magazine account also reported that the Neanderthal receptor differs by two amino acid changes and one small deletion, and that the variant is especially common in South and East Asia where nearly one in four people carries it.

Across the reporting, the same publication details were tied to Current Biology, with the Karolinska Institutet release listing "Increased signaling of the Neanderthal growth hormone receptor" and an online date of August 5, 2026, along with DOI: 10.1016/j.cub.2026.07.025.