Part of our musculature may still bear traces of encounters that took place tens of thousands of years ago. A Neanderthal version of a growth-related receptor is still present in some humans, especially in Asia, and is associated with greater muscle mass.
The receptor studied here captures growth hormone. Once the signal is received, it triggers several reactions involved in tissue development, metabolism, and muscle maintenance.
© Neanderthal Museum, Mettmann, Germany, CC BY 4.0
Its origin is what makes it distinctive. This version of the receptor was passed on through interbreeding between Homo sapiens and Neanderthals. The latter disappeared about 40,000 years ago, but some of their DNA still circulates in present-day human populations.
What does this variant actually change? In the laboratory, cells carrying it transmit the growth hormone signal more strongly. In other words, the hormone does not send a different message, but the cell seems to respond with greater intensity.
This obviously does not turn every carrier into an athlete. Strength and build depend on many factors: physical activity, diet, age, sex, and the whole genetic heritage. Here, the researchers observe an average association, not a rule valid for every person.
The data studied nonetheless point in the same direction. Carriers have, on average, more lean mass, a measure that mainly includes muscles.
One might think such a heritage belongs only to ancient history. Yet it still acts on a very concrete function of the human body. Other Neanderthal fragments have already been linked to immunity or certain physical traits; this one directly concerns how cells respond to a hormone.
In past environments, slightly more developed musculature may have helped to support exertion or preserve strength. The authors remain cautious on this point. A possible advantage once does not automatically become beneficial in a modern life, often more sedentary.
Now the task is to measure the effect more precisely. Future research will need to compare ages, populations, and activity levels, then determine whether this variant also influences metabolism or certain medical risks.