“The Neanderthal genome sequence confirmed that they evolved largely in isolation from modern humans for half a million years.” “Although the main admixture event between Neanderthals and modern humans likely took place some 47,000 years ago, findings over the last decade also support some admixture prior to the main expansion of modern humans out of Africa.” To understand the robust build of Neanderthals, the researchers examined the growth hormone receptor, a protein that helps control how the body responds to growth hormone released by the pituitary gland. The differences were not detectable in children, suggesting they emerge around puberty, when growth hormone levels rise sharply. Increased signaling of the Neanderthal growth hormone receptor.