Neanderthal growth hormone receptor increases muscle mass in people today

Growth hormone helps shape the body by regulating the growth of muscles and bones. It is released by the pituitary gland at the base of the brain and travels through the bloodstream. To act on a cell, the hormone must bind to a receptor on its surface, which then passes the signal into the cell.

An international team led by Hugo Zeberg of Karolinska Institutet and Philipp Kanis of the Max Planck Institute for Evolutionary Anthropology found that the Neanderthal version of this receptor has two changes that are not present in the version most common in modern humans.

Neanderthal variant responds more strongly to growth hormone

The study shows that laboratory-grown cells with the Neanderthal receptor responded more strongly to growth hormone. They grew 40 percent more than cells with the more common modern human receptor. The researchers linked most of this stronger response to one of the two Neanderthal-specific changes.

Modern humans inherited this version of the receptor through interbreeding with Neanderthals around 47,000 years ago. Today, it is particularly common in South and East Asia. Up to 24 percent of people in some South Asian populations carry it, compared with around 0.5 percent of Europeans.

“What struck me most was that two very different types of evidence told the same story,” says Philipp Kanis, first author of the study and 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.”

Differences first become apparent after childhood

The difference appears to emerge only after childhood. The researchers examined body measurements from more than 6,000 children and found no link between the Neanderthal version and growth up to the age of eleven. This suggests that its effects may become noticeable later, possibly around puberty, when growth hormone levels increase substantially. Among adults, people carrying the Neanderthal version had, on average, around 270 grams more muscle mass.

“As someone who does CrossFit, I was delighted to find Neanderthal genetics and muscle mass coming together in the same study,” says co-author Miriam Berreiter. “But even a Neanderthal growth hormone receptor is no substitute for training.”

The Neanderthal version was also linked to subtle differences in the skull and teeth. Carriers tended to have a slightly shorter rear section of the lower jaw and shorter tooth roots. Both features are closer to what was typical of Neanderthals.

“It is fascinating that one genetic change inherited from Neanderthals can still have an effect on the human body today,” says Hugo Zeberg, senior author of the study. “But this is only one of many genetic influences on growth and body shape. It cannot explain the Neanderthal body type on its own, and it certainly does not determine a person’s overall appearance.”

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Article Source: Max Planck Institute for Evolutionary Anthropology news release.