Neanderthals did not interbreed with humans, scientists find

The genetic traits between humans and Neanderthals are more likely from a shared ancestry rather than interbreeding, a British study has suggested.

Cambridge University researchers concluded that the DNA similarities were unlikely to be the result of human-Neanderthal sex during their 15,000-year coexistence in Europe.

People living outside Africa share as much as four per cent of their DNA with Neanderthals, a cave-dwelling species with muscular short arms and legs and a brain slightly larger than ours.

The Cambridge researchers examined demographic patterns suggesting that humans were far from intimate with the species they displaced in Europe almost 40,000 years ago.

The study into the genomes of the two species, found a common ancestor 500,000 years ago would be enough to account for the shared DNA.

Their analysis, published in the journal Proceedings of the National Academy of Sciences (PNAS), contradicts recent studies that found inter-species mating, known as hybridisation, probably occurred.

[...]

A previous study in 2010 suggested that interspecies liaisons near the Middle East resulted in Neanderthal genes first entering humans 70,000 years ago.

Modern non-Africans share more with Neanderthals than Africans, supporting the claim that the mixing occurred when the first early humans left Africa to populate Europe and Asia.

The existence of a 500,000-year-old shared ancestor that predates the origin of Neanderthals provides a better explanation for the genetic mix.

Diversity within this ancestral species meant that northern Africans were more genetically similar to their European counterparts than southern Africans through geographic proximity.

This likeness persisted over time to account for the overlap with the Neanderthal genome we see in modern people today.

[...]

“The idea is that our African ancestors would not have been a homogeneous, well-mixed population but made of several populations in Africa with some level of differentiation, in the way right now you can tell a northern and southern European from their looks,” she said.

”œBased on common ancestry and geographic differences among populations within each continent, we would predict out of Africa populations to be more similar to Neanderthals than their African counterparts ”“ exactly the patterns that were observed when the Neanderthal genome was sequenced, but this pattern was attributed to hybridisation.

“Hopefully, everyone will become more cautious before invoking hybridisation, and start taking into account that ancient populations differed from each other probably as much as modern populations do.”

Northern Africans would be more similar to Europeans and ancient similarity stayed because there wasn’t enough mixing between northern and southern Africans.

Previously: Neanderthals live on in DNA of humans

2 comments to Neanderthals did not interbreed with humans, scientists find

  • Raja

    Monkeys Show Why It’s Hard to Prove Ancient Human Interbreeding

    Live Science, By Megan Gannon, December 7

    A bundle of recent genetic studies have suggested that modern humans had sex with Neanderthals thousands of years ago when the two populations roamed the planet alongside each other. However, the bones left behind by the two species don’t bear any obvious traces of interbreeding and a new study of monkeys in Mexico shows why we shouldn’t expect them to.

    Researchers examined blood samples, hair samples and measurements collected from mantled howler monkeys and black howler monkeys that were live-captured and released in Mexico and Guatemala between 1998 and 2008. The two monkey species splintered off from a common ancestor about 3 million years ago and today they live in mostly separate habitats, except for a “hybrid zone” in the state of Tabasco in southeastern Mexico, where they coexist and interbreed.

    Through an analysis of genetic markers, from both mitochondrial and nuclear DNA, the researchers identified 128 hybrid individuals that were likely the product of several generations of interbreeding. But these hybrids shared most of their genome with either one of the two species and were physically indistinguishable from the pure individuals of that species, the team found.

  • Raja

    Neanderthals Died Out Earlier Than Thought

    LiveScience, By Charles Choi, Contributor, February 4

    Neanderthals may have died out earlier than before thought, researchers say.

    These findings hint that Neanderthals did not coexist with modern humans as long as previously suggested, investigators added.

    Modern humans once shared the planet with now-departed human lineages, including the Neanderthals, our closest known extinct relatives. However, there has been heated debate over just how much time and interaction, or interbreeding, Neanderthals had with modern humans.

    [...]

    Their data suggest that modern humans and Neanderthals may have actually lived in the area at completely different times, never crossing paths there at all. Even so, these findings do not call into question whether modern humans and Neanderthals once had sex — the findings simply indicate this interbreeding must have occurred earlier, before modern humans entered Europe.

    “The genetic evidence for interbreeding — 1 to 4 percent Neanderthal DNA in present-day modern humans — suggests that interbreeding probably occurred before the period we are looking at in the Levant, the region around Israel and Syria, when modern humans first migrated out of Africa,” researcher Rachel Wood, an archaeologist and radiocarbon specialist at Australian National University in Canberra, told LiveScience.

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