Traces of Neanderthal ancestry still shape human physiology, and a study in Current Biology led by Karolinska Institutet with the Max Planck Institute for Evolutionary Anthropology adds a muscular example. The team examined a growth hormone receptor variant inherited from Neanderthals and found that cells carrying it respond more strongly to growth hormone, growing roughly 40 per cent more than cells with the common modern version when exposed to the hormone in laboratory experiments.
Population data gave the finding a real-world anchor. Analysis of more than 1.1 million adults linked the variant to around 285 grams of additional body weight, mostly muscle. Data on children up to age 11 showed no clear association with growth measures, suggesting the effect emerges around puberty, consistent with its tie to pituitary rather than placental growth hormone. Carriers also showed slightly shorter lower jaws and tooth roots, hinting at broader developmental effects.
The variant is most common in South and East Asian populations and rare in Europeans, a distribution that itself raises evolutionary questions about where and why it persisted. The researchers emphasise perspective: the effect on muscle is modest compared with what training achieves, but the study is an elegant demonstration of how archaic DNA continues to tune modern human biology.