Some people today carry a version of the growth hormone receptor inherited from Neanderthals. This ancient DNA appears to make cells respond more strongly to growth hormone. This could lead to more muscle mass in adults.
Neanderthals were generally more muscular than most modern humans. Evidence from their skeletons shows they had significant muscle mass. They also had distinct features like strong brow ridges and shorter tooth roots.
How Neanderthal DNA Boosts Growth
Growth hormone is crucial for developing muscles and bones. The pituitary gland in the brain produces it. The hormone travels through the blood and attaches to receptors on cell surfaces. These receptors then send the hormone's signal into the cell.
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Start Your News DetoxResearchers, led by Hugo Zeberg and Philipp Kanis, studied the Neanderthal version of this receptor. They found two specific changes not present in the most common modern human receptor.
When tested in lab cells, the Neanderthal receptor showed a 40% stronger response to growth hormone. This meant the cells grew more. One of the two Neanderthal-specific changes caused most of this increased response.
This receptor variant entered the modern human gene pool about 47,000 years ago. This happened when modern humans and Neanderthals interbred.
Today, its frequency varies. Up to 24% of people in some South Asian populations carry it. It is also common in East Asia. In Europe, about 0.5% of people have it.
Philipp Kanis, the study's first author, was surprised by how well the lab and population data matched. "It is rare to see laboratory and population evidence fit together so clearly," he noted.
Effects in Adults
The Neanderthal receptor's influence doesn't show up in early childhood. Researchers looked at measurements from over 6,000 children. They found no link to growth up to age eleven.
This suggests the effects might appear later, possibly around puberty. This is when growth hormone levels significantly increase. Among adults, those with the Neanderthal version had about 270 grams more muscle mass on average.
Miriam Berreiter, a co-author, joked that even with Neanderthal genetics, training is still necessary for muscle.
The inherited receptor variant also links to small differences in the skull and teeth. Carriers tended to have a slightly shorter back part of the lower jaw and shorter tooth roots. These features are more typical of Neanderthals.
Hugo Zeberg, the study's senior author, finds it "fascinating" that one genetic change from Neanderthals still affects the human body. However, he stressed that it's just one of many genetic factors influencing growth and body shape. It cannot fully explain the Neanderthal body type or a person's overall appearance.
Deep Dive & References
Increased signaling of the Neanderthal growth hormone receptor - Current Biology, 2026
