Neanderthal Gene Linked to Greater Muscle Mass in Modern Humans

A Neanderthal gene variant linked to greater muscle mass and increased height in modern humans entered the gene pool through interbreeding roughly 47,000 years ago, according to a study published in Current Biology. Researchers found that this genetic variation affects how cells respond to growth hormone, with carriers today showing distinct differences in muscle mass, height, and facial anatomy depending on their geographic ancestry.

Uncovering the Neanderthal Growth Hormone Receptor

Scientists analyzed ancient DNA from ten Neanderthal samples and two Denisovan samples, comparing those genetic sequences with biobank data from more than 1.1 million modern human genomes. According to the research, almost all Neanderthals carried the specific gene variant, which controls a receptor called GHR that binds to growth hormone. When compared with the typical modern human form, the Neanderthal GHR features two amino acid changes and a small DNA deletion.

To test how these genetic differences function in living tissue, researchers engineered mouse cells to produce both the Neanderthal and modern human versions of the receptor. According to findings reported by Nature, cells carrying the Neanderthal receptor proliferated about 39% to 40% faster over a five-day period when exposed to growth hormone produced by the pituitary gland. Tests identified a single amino acid change as the primary driver behind this heightened internal cell signaling.

Geographic Distribution and Modern Human Traits

The frequency of the Neanderthal gene variant varies sharply across different modern populations. According to data cited by Live Science, the variant is exceptionally rare among people of European ancestry, appearing in roughly 0.5% to 1% of populations. By contrast, it occurs much more frequently in parts of Asia, showing up in about 15% to 20% of people with East Asian ancestry, roughly 20% to 24% of South Asian populations, and peaking near 25% in specific Pakistani groups. It is absent in people of sub-Saharan Africa, likely because ancient interbreeding occurred primarily in Eurasia.

When looking at physical traits in modern adults, the functional differences are measurable. Philipp Kanis, a genetics researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, noted that individuals carrying the variant possess roughly 0.25 to 0.27 kilograms of additional muscle mass per copy of the gene, alongside an average height increase of about 0.3 centimeters, according to Nature and the primary study.

Craniofacial Features and Pubertal Development

The phenotypic effects of the ancient gene do not manifest immediately during early childhood. Researchers observed no clear physical differences among carriers up to age 11. Instead, the traits emerge later, aligning with the period during puberty when natural growth hormone levels surge in the human body.

In addition to muscle and height changes, carriers exhibit subtle anatomical features reminiscent of Neanderthal skeletal structures. According to study data, these traits include a shorter ramus—the rear portion of the lower jaw—along with a higher statistical risk of developing an overbite and possessing shorter tooth roots. Bastien Llamas, a human geneticist at Adelaide University in Australia, told Nature that the study provides an unusually detailed molecular pathway connecting ancient genomics directly to measurable physical variations in present-day humans.

Frequently Asked Questions

How do researchers know this gene came from Neanderthals?

Scientists extracted DNA from high-coverage and medium-coverage Neanderthal and Denisovan fossils, identifying unique amino acid sequences and deletions that matched patterns found in specific modern human genomes.

Does this gene explain the entire robust Neanderthal body type?

No. According to study co-author Hugo Zeberg, the GHR variant cannot account for the entire stocky Neanderthal physique on its own. Robustness was shaped by many interacting genes, as well as developmental, lifestyle, and environmental factors.

Why is the gene variant more common in Asia than in Europe?

Interbreeding between early modern humans and Neanderthals occurred in Eurasia tens of thousands of years ago, and demographic shifts, genetic drift, and natural selection subsequently influenced how frequently specific archaic segments survived within different regional populations over millennia.