Neandertals were a robust and muscular species, with bones that hinted at powerful muscles and distinctive facial features. Now, a recent study has uncovered a fascinating connection between their genetic legacy and modern muscle mass. The key lies in a hormone receptor, a protein on the surface of cells that acts as a gateway for growth hormone. This hormone, released by the pituitary gland, regulates muscle and bone growth, and its impact is profound.
An international research team, led by Hugo Zeberg of Karolinska Institutet and Philipp Kanis of the Max Planck Institute for Evolutionary Anthropology, made a groundbreaking discovery. They found that the Neandertal version of this receptor has two unique changes not present in the version most common in modern humans. These changes have a significant impact on how the receptor interacts with growth hormone.
In laboratory experiments, cells with the Neandertal receptor responded more strongly to growth hormone, resulting in 40% more growth compared to cells with the modern human receptor. This finding is particularly intriguing because it suggests that the Neandertal version of the receptor enhances muscle mass, a trait that was advantageous for Neandertals in their environment. The study also revealed that this difference becomes apparent only after childhood, possibly around puberty, when growth hormone levels surge.
The inheritance of this Neandertal receptor variant from interbreeding with Neandertals around 47,000 years ago has had a lasting impact. It is now prevalent in South and East Asian populations, with up to 24% of individuals carrying it. This genetic legacy has contributed to the diverse physical traits observed in modern humans, particularly in muscle mass.
Miriam Berreiter, a co-author of the study and a CrossFit enthusiast, expressed excitement about the findings. She noted that while the Neandertal growth hormone receptor might offer some advantages, it is no substitute for physical training. This highlights the complex interplay between genetics and environment in shaping human physiology.
The study also uncovered subtle differences in the skull and teeth of individuals carrying the Neandertal receptor variant. These differences, such as a slightly shorter rear section of the lower jaw and shorter tooth roots, are closer to what was typical of Neandertals. This finding underscores the ongoing influence of Neandertal genetics on modern humans, even after thousands of years of separation.
Hugo Zeberg, the senior author, emphasized the importance of understanding the genetic influences on growth and body shape. He noted that while the Neandertal receptor variant contributes to muscle mass, it is just one of many genetic factors at play. The overall appearance of an individual is a complex interplay of genetics and environmental factors.
This research provides a fascinating glimpse into the enduring impact of Neandertal genetics on modern humans. It highlights the intricate relationship between our ancient ancestors and our present-day physiology, offering a deeper understanding of human evolution and the role of genetic inheritance in shaping our bodies.
