Study suggests humans mated with Neanderthals

[Imperial Overlord]

CSM

Humans today could be part Neanderthal, according to a new study that found our ancestors interbred with an extinct hominid species some millennia ago.

Neanderthals walked the Earth between about 130,000 and 30,000 years ago. While they co-existed with modern humans for a while, eventually they went extinct and we didn't. There has been intense scientific debate over how similar the two species were, and whether they might have mated with each other.

"The issue has been highly contentious for some time," said University of New Mexico genetic anthropologist Keith Hunley.

Last week at the annual meeting of the American Association of Physical Anthropologists in Albuquerque, N.M., Hunley and colleagues presented the results of a new study that found evidence for interbreeding between modern humans and some other extinct ancient human species – either Neanderthals (Homo neanderthalensis) or another group such as Homo heidelbergensis. The research was first reported by NatureNews.

The researchers looked at DNA samples from humans living today, and found signs of leftover Neanderthal genes introduced from this interbreeding. They looked at genetic data from almost 2,000 people around the world, and calculated how much genetic variation existed between samples. The results indicate that some extinct group of hominids mixed their genes with ours at two points in history, Hunley said.

One period of interbreeding probably occurred shortly after Homo sapiens migrated out of Africa around 60,000 years ago. The researchers found an excess of genetic diversity in all modern people except Africans, suggesting that the influx of Neanderthal-like DNA came after the exodus from Africa.

A second period of interbreeding is suggested by the fact that the researchers measured even more genetic diversity among people of Oceanic descent – people from Australia, New Zealand, New Guinea and other Pacific islands.

"I think we show there's clear evidence in the genome of living people of this mixture," Hunley told LiveScience. "The fact that there's a clear signal implies that there was some significant amount" of interbreeding, he said.

This work is the first time scientists have used DNA from living people to look at this question, Hunley said.

In an earlier study, Erik Trinkaus of Washington University in St. Louis found suggestions of Neanderthal and modern human interbreeding by comparing ancient bone fossils from the two species.

Trinkaus said the new work fits into his findings, though he hasn't reviewed the details yet since Hunley's paper has not yet been published in a peer-reviewed journal. "The conclusion makes sense and fits with the majority of the data available," Trinkaus said.

Another anthropologist who has studied Neanderthal anatomy agreed.

"I have been arguing for this position throughout my career, ever since I began to study Neandertals and other populations," said Milford Wolpoff of the University of Michigan. "It has always seemed clear that some Neandertal anatomy appears in living populations."

Not everyone, though, will be easily convinced yet, Hunley said.

I know earlier genetic studies hadn't found evidence of interbreeding, which had otherwise seemed very likely, but I didn't know they hadn't used genetic material from modern humans in their tests. Taking it from present day humans is a much better way to test, since the donor in question could have died before the two groups mixed. Of course the paper hasn't undergone full peer review yet, so if there are flaws in the methodology they'll likely to come to light in the near future. My father, who is an archeologist, has always favored the idea of interbreeding. I'll have to email him a link to the article and get his thoughts on the matter.

[Sarevok]

Is not the definition of a species that two individuals can mate ? If so does not that make Neanderthals and humans same species ?

Forgive my ignorance but I have zero knowledge of all matters biology and would like to be enlightened.

[Johonebesus]

Is not the definition of a species that two individuals can mate ? If so does not that make Neanderthals and humans same species ?

Forgive my ignorance but I have zero knowledge of all matters biology and would like to be enlightened.

Basically, but there is no clear cut definition. Wolves and coyotes can interbreed freely, as can brown and polar bears. In fact, wolves in the north eastern part of the continent have a large amount of coyote DNA. Red wolves might have originated as a hybrid population. Interbreeding with Neanderthals would not necessarily mean that they are the same species as us.

[Anguirus]

^ It's a bit more complicated than that.

First of all, I will simplify. There are HUNDREDS of proposed concepts for the definition of a "species." None of them is quite acceptable to everyone. However, the one that is most often used and the one that is most biologically relevant is the one that you are referring to, the "biological species concept," or BSC. I will focus on explaining this.

The BSC follows from the fact that it is meaningless to talk about two different "species" if these putative species can and do interbreed, without a clear preference. Two putative species are only biologically relevant/distinct entities if there is a barrier to gene flow. Gene flow is just migration and subsequent breeding between these two putative species.

Barriers to gene flow can take many forms, however. A short list off the top of my head: physical barriers, temporal barriers (like being active at different times), behavioral barriers (such as different mating dances or calls), mechanical barriers (equipment doesn't line up), chemical barriers (many species are set up to chemically kill any sperm that doesn't "match"), and post-zygotic barriers such as hybrid inviability (mixing incompatible genes leads to spontaneous abortion or otherwise early death), hybrid infertility, or hybrid breakdown (second-generation hybrids are infertile).

These barriers do not spring up all at once between closely related species. In fact, the most classic and well-established model for speciation is allopatry, in which a single population is bisected by an insurpassable barrier. In this case, these two putative species may have no problems breeding in the lab, but in the wild they do not crossbreed in any meaningful sense. Therefore genetic drift, and possibly selective pressures, will affect these two putative species independently and cause them to diverge.

It is possible that this barrier will come down. In this case, one of two things can happen. Either there are no other effective barriers to reproduction, so that these two species will actually fully merge and become one species. Or, they have diverged enough so that no or relatively little breeding will occur. Gene flow may well resume between the two species through hybrids, but they are likely to retain a distinct character. In many cases, the hybrids themselves can become a true-breeding third species!

With that background, it's easy to see how Neandertal genes could have entered our genome. Neandertals migrated out of Africa, started evolving on their own thanks to the barrier between it and African humans, and then a migration of sapiens comes into secondary contact with it. The two species clearly did not re-merge, but a relativbely small number of fertile hybrids introduced novel genes into the sapiens genome.

[Themightytom]

Well that's a slap in the face for racists. they can't really claim that African Americans are throwbacks if interbreeding with neanderthals happened after we migrated out of Africa..

[spaceviking]

I assume they will now claim the white race carries the noble genes of the Neanderthal, though it would actually be interesting to see if there are any real differences between populations with relatively high Neanderthal heritage compared to those with none.

[Liberty]

Sounds very Clan of the Cave Bears to me...

[Jeremy]

spaceviking, that has been freely discussed among them for a long time.

This reads as if the Australian Aborigines and Indian Ocean Negritos are the most intermixed. Basically, the earliest African Exodus populations of Sapiens ran into other Humans and made friends.

Also, after most Sapiens dumped back into East Africa after the Toba Catastrophe, the Neanderthals became prevalent in the Middle East again. Sapiens reemerged and made friends with some of the Neanderthals.

Fairly simple and it makes sense. I've heard an argument before that most of the Homo "species" are really just different extinct races of our species. The Bear example would be seemingly pertinent in discussion of that argument.

[General Zod]

Is not the definition of a species that two individuals can mate ? If so does not that make Neanderthals and humans same species ?

Forgive my ignorance but I have zero knowledge of all matters biology and would like to be enlightened.

Whether or not they can produce fertile offspring is a bit more important than just being able to mate, iirc.

[Tanasinn]

I was under the impression that this proposal was no longer considered valid and that studies had found no neanderthal contribution to the human gene pool.

[Imperial Overlord]

I was under the impression that this proposal was no longer considered valid and that studies had found no neanderthal contribution to the human gene pool.

The article mentions that. According to it, the human samples were ancient human remains (presumably from a similar time period and region as the neanderthals), not modern humans like this study. Of course this paper has just being presented and there will undoubtedly be follow up peer review. The conclusion, after further review, could prove false.

[Molyneux]

I was under the impression that this proposal was no longer considered valid and that studies had found no neanderthal contribution to the human gene pool.

That's the great thing - all it takes is one study to throw things into motion again.
Personally, I hope that this is true - though I know that preference has no real place in science - and it's always neat to see a question re-opened.

[Anguirus]

Yep! Science marches on! One way or another.

[mr friendly guy]

Is not the definition of a species that two individuals can mate ? If so does not that make Neanderthals and humans same species ?

Forgive my ignorance but I have zero knowledge of all matters biology and would like to be enlightened.

Its a bit more complicated that that. What we call a species is just the way we categorise things, and in reality its best to think of species on a continuum rather than discrete units. Thus two species at the furthest edges of the continuum may not mate, however species close together may still do so.

Now if you want real life examples, they are called "ringed species". Essentially several distinct groups live adjacent to each other in a ring shape. To illustrate lets say group A lives next to B, which lives next to C, which lives next to D, which lives next to E, which lives next to A. So A is next to B and E (but not to C & D), B is next to A and C (but not D & E) and so on. A has been observe to reproduce with B, B to reproduce with C, C with D, and D reproduces with E.

Now here is the interesting part. If you suppose that individuals of the same species essentially are two individuals which can mate, then one would conclude that group E is of the same species as group A, and we would expect E to reproduce with A. Except it doesn't happen, which under your definition would have E a different species from A. This just illustrates that species are on a continuum rather than discrete units.

In Richard Dawkin's book (I think its climbing Mount Improbable) he lists two examples of ringed species, one was a salamder in the US and the other was some European birds.

[Alyrium Denryle]

In Richard Dawkin's book (I think its climbing Mount Improbable) he lists two examples of ringed species, one was a salamder in the US and the other was some European birds.

Yep. The Ensantina salamanders exist as ring species with the following range.



Those adjascent to eachother can interbreed, those on the other side cannot. However they all exchange genes via gene flow with all of the others because of hybridization.

Honestly though, reptiles and amphibians rape the biological species concept six ways from sunday. The entire Bufo Americanus complex is one massive hybridization clusterfuck. Entire new stable species have been formed by it among whiptail lizards. I can go on and on...

[cosmicalstorm]

I've never been able to understand why mating between humans and neanderthals would not occur? Humans have sex with dogs, cows, trees, in many countries rape is still something of a national sport. If the two ever lived close to each other, and if humans were dominating them with superior skills, of course they fucked their women as well.

[Eframepilot]

I've never been able to understand why mating between humans and neanderthals would not occur? Humans have sex with dogs, cows, trees, in many countries rape is still something of a national sport. If the two ever lived close to each other, and if humans were dominating them with superior skills, of course they fucked their women as well.

It's not the physical mating that's doubted but rather the compatibility to produce offspring that are non-sterile.

[Temujin]

I've never been able to understand why mating between humans and neanderthals would not occur? Humans have sex with dogs, cows, trees, in many countries rape is still something of a national sport. If the two ever lived close to each other, and if humans were dominating them with superior skills, of course they fucked their women as well.

It's not the physical mating that's doubted but rather the compatibility to produce offspring that are non-sterile.

I have no doubt that interbreeding occurred, but I figured that like mules, the offspring were generally sterile. But even a small number weren't, I could see a few instances of Neanderthal genes showing up in modern humans.

[PaperJack]

Can love bloom between two different races ?

[ray245]

Can love bloom between two different races ?

Races as in?

[Molyneux]

Can love bloom between two different races ?

Races as in?

I think he's using "race" to mean "species"...possibly. At least, given that the thread topic is possible proof of past Human+Neanderthal boinking.

[Alyrium Denryle]

Can love bloom between two different races ?

If by races you means species... It may. More than likely it was rape. That may be my cynicism talking though

[Junghalli]

If by races you means species... It may. More than likely it was rape. That may be my cynicism talking though

I imagine it was probably some of both.

[GrandMasterTerwynn]

Can love bloom between two different races ?

I'm hoping you mean species, but I don't see why not. Humans and Neanderthal are approximately the same shape and size and probably share similar mating behaviors. Sure, the average human is too skinny for the average Neanderthal and the average Neanderthal is too stocky and barrel-shaped for the average human . . . but stranger consensual pairings have occurred within the human species. Google Shaquille O'Neal and his ex-wife sometime as an example (he's at least double her weight and probably 50% taller than she is.)

[Coyote]

Wolves and coyotes can interbreed freely, as can brown and polar bears. In fact, wolves in the north eastern part of the continent have a large amount of coyote DNA.

She said she was 18 in human years. That's my story, and I'm sticking to it.

But seriously folks, this would make humans and Neanderthals in the same... family? Because wolves, coyotes and dogs are all "Canis-" (lupus; latrans; and familiaris respectively). Sure, we came from a similar simian ancestor, but the path brachiated and then re-formed?