Neanderthal growth hormone receptor increases muscle mass in people today, study shows

A new study reveals that a genetic variant inherited from Neanderthals enhances muscle mass in modern humans, according to research published in Current Biology. Scientists identified that the Neanderthal version of the growth hormone receptor, which differs from the most common form in contemporary humans, elicits a stronger biological response to growth hormones. This discovery highlights how ancient genetic legacies continue to influence human physiology today. The research, led by Hugo Zeberg of Karolinska Institutet and Philipp Kanis of the Max Planck Institute for Evolutionary Anthropology, focused on the growth hormone receptor gene. Neanderthals, known for their robust physical build, possessed a distinct variation of this gene. The study found that this Neanderthal variant contains two specific mutations absent in the dominant modern human version of the receptor. When tested in laboratory conditions, cells equipped with the Neanderthal receptor demonstrated a 40 percent greater response to growth hormone stimulation compared to those with the standard human receptor. This heightened sensitivity was largely attributed to one of the two mutations. The Neanderthal variant entered the human genome approximately 47,000 years ago through interbreeding between early modern humans and Neanderthals. Present-day prevalence varies significantly across regions, with up to 24 percent of individuals in certain South Asian populations carrying the variant. In contrast, less than 0.5 percent of European populations possess this genetic trait. The disparity underscores the complex patterns of genetic inheritance shaped by historical interactions between human groups. The physiological impact of the Neanderthal receptor becomes evident after childhood. Researchers analyzed body measurements from over 6,000 children and found no correlation between the presence of the Neanderthal variant and growth before the age of 11. However, among adults, carriers exhibited an average increase of 270 grams, approximately 9.5 ounces, in muscle mass. These findings suggest that the genetic influence manifests during adolescence, coinciding with increased growth hormone production. In addition to affecting muscle mass, the Neanderthal receptor variant is associated with minor anatomical differences. Individuals carrying the variant tend to have a slightly shorter posterior portion of the mandible and shorter tooth roots, traits reminiscent of Neanderthal skeletal characteristics. These subtle variations indicate that the genetic legacy extends beyond muscular development, influencing craniofacial morphology. Philipp Kanis emphasized the significance of aligning laboratory results with real-world observations. He noted that both cellular experiments and data from over a million individuals consistently pointed to similar outcomes, reinforcing the validity of the findings. Co-author Miriam Berreiter, who engages in CrossFit training, expressed personal interest in the connection between Neanderthal genetics and muscle mass, though she acknowledged that the genetic factor alone does not replace the importance of physical exercise. Zeberg highlighted that while the Neanderthal receptor contributes to human physiology, it represents just one of many genetic factors influencing body composition and growth. The study does not fully account for the distinctive Neanderthal physique nor dictate an individual’s overall appearance. Instead, it illustrates the ongoing interaction between ancient genetic contributions and modern human traits. The study titled “Increased Signalling of the Neanderthal Growth Hormone Receptor” was published in Current Biology on August 5, 2026, under the DOI 10.1016/j.cub.2026.07.025. Researchers anticipate further investigations into the broader implications of Neanderthal genetic variants on human health and physical attributes.