Neanderthals vanished roughly 42,000 years ago, but a piece of their biology appears to be quietly at work in some people today, according to a new study led by scientists from the Max Planck Institute for Evolutionary Anthropology.
Aspects of Neanderthal anatomy live on in people today. Image credit: Holger Neumann / Neanderthal Museum.
“Neanderthals are the most well-known among archaic human forms,” said Dr. Philipp Kanis, a postdoctoral researcher at the Max Planck Institute for Evolutionary Anthropology and his colleagues.
“They appeared in the fossil record approximately 300,000 to 400,000 years ago, inhabited western Asia and Europe, and became extinct around 42,000 years ago.”
“Neanderthals had more robust bodies and larger brains than present-day humans.”
“Their defining characteristics include prominent brow ridges, an occipital bun at the back of the skull, a barrel-shaped thorax, greater muscle mass, and short-rooted teeth (taurodontism).”
“Although none of these traits are unique to Neanderthals, the combination of these features is distinctive and led early researchers to propose that they represented a separate evolutionary lineage.”
“The Neanderthal genome sequence confirmed that they evolved largely in isolation from modern humans for half a million years.”
“However, they were not completely isolated. Before their extinction, Neanderthals interbred with modern humans. As a result, people with non-African roots today carry approximately 2% Neanderthal DNA.”
“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.
Comparing modern human DNA with high-quality Neanderthal genomes, they found that Neanderthals carried a distinctive version of the receptor, marked by two amino acid changes not found in Africans today.
When they inserted the Neanderthal version of the receptor into lab-grown cells and exposed them to growth hormone, the cells multiplied faster and showed stronger downstream signaling than cells carrying the modern human version.
Because Neanderthals interbred with the ancestors of modern non-African populations, the gene variant was passed down and survives today, particularly in South and East Asia, where it can be found in roughly a fifth of some populations.
It is rare or absent in sub-Saharan Africa, consistent with populations there having little to no Neanderthal ancestry.