Neandertal genes found in all non-African populations

[Bikewer]

Slashdot reports the following story:

(the headline blurb)

"Neanderthal Genes Found In All Non-African Populations
Med-trump writes "Neanderthals, whose ancestors left Africa about 400,000 to 800,000 years ago, evolved in what is now mainly France, Spain, Germany and Russia, and are thought to have lived until about 30,000 years ago. Now scientists have identified a piece of Neanderthal DNA (called a haplotype) in the human X chromosome and conclude that this haplotype is present because of mating between our ancestors and Neanderthals. The study was published in the latest issue of the journal Molecular Biology and Evolution."

Makes a certain sense, if Neanderthal was not present in Africa, then those populations that stayed put wouldn't have had any opportunity to....Become friendly.

 

[randman]

Slashdot reports the following story:

(the headline blurb)

"Neanderthal Genes Found In All Non-African Populations
Med-trump writes "Neanderthals, whose ancestors left Africa about 400,000 to 800,000 years ago, evolved in what is now mainly France, Spain, Germany and Russia, and are thought to have lived until about 30,000 years ago. Now scientists have identified a piece of Neanderthal DNA (called a haplotype) in the human X chromosome and conclude that this haplotype is present because of mating between our ancestors and Neanderthals. The study was published in the latest issue of the journal Molecular Biology and Evolution."

Makes a certain sense, if Neanderthal was not present in Africa, then those populations that stayed put wouldn't have had any opportunity to....Become friendly.

Wouldn't that make Neanderthals more of a human tribe than separate species?

 

[Skeptic Ginger]

Wouldn't that make Neanderthals more of a human tribe than separate species?

I'm pretty sure the amount of DNA is pretty small. It's not like we interacted in a big cross breeding way. The actual evidence here is simply that the Neanderthal genes entered the population after humans migrated out of Africa. That is how the genetic trail of human migration has been and is being mapped. Whenever a mutation occurs on the mitochondrial DNA or the Y chromosome, it indicates a point in time that mutation begins to appear.

We use the Y chromosome and the mitochondrial DNA because everyone who is a descendent from then on will have it. Men don't get a combo of two Y chromosomes mixed from each parent so the genetic line is straight. Of course if there are no male offspring the mutation trail can go cold. The mitochondrial DNA mutations are more persistent.

And being found in all non-African populations is not the same as being found in all non-African individuals but let me look into this research.

 

[Skeptic Ginger]

Here's the abstract of the actual science:

An X-Linked Haplotype of Neandertal Origin Is Present Among All Non-African Populations

Recent work on the Neandertal genome has raised the possibility of admixture between Neandertals and the expanding population of Homo sapiens who left Africa between 80 and 50 Kya (thousand years ago) to colonize the rest of the world. Here, we provide evidence of a notable presence (9% overall) of a Neandertal-derived X chromosome segment among all contemporary human populations outside Africa. Our analysis of 6,092 X-chromosomes from all inhabited continents supports earlier contentions that a mosaic of lineages of different time depths and different geographic provenance could have contributed to the genetic constitution of modern humans. It indicates a very early admixture between expanding African migrants and Neandertals prior to or very early on the route of the out-of-Africa expansion that led to the successful colonization of the planet.

 

[Skeptic Ginger]

Here's some more data:

A Draft Sequence of the Neandertal Genome

Neandertals, the closest evolutionary relatives of present-day humans, lived in large parts of Europe and western Asia before disappearing 30,000 years ago. We present a draft sequence of the Neandertal genome composed of more than 4 billion nucleotides from three individuals. Comparisons of the Neandertal genome to the genomes of five present-day humans from different parts of the world identify a number of genomic regions that may have been affected by positive selection in ancestral modern humans, including genes involved in metabolism and in cognitive and skeletal development. We show that Neandertals shared more genetic variants with present-day humans in Eurasia than with present-day humans in sub-Saharan Africa, suggesting that gene flow from Neandertals into the ancestors of non-Africans occurred before the divergence of Eurasian groups from each other.

The full article is free at the link.

 

[Skeptic Ginger]

Lots of interesting tid bits here. Apparently we get most of our leukocyte antigen alleles from Neanderthal DNA so it had some selection advantage. Makes me curious as to how African and other populations' white blood cells differ.

 

[Skeptic Ginger]

There's a wealth of information about human migration mapped via DNA here, including an interactive map (click "skip intro", then "click to begin") you can find lineages on.

 

[randman]

But basically they were a tribe of people that mated with the tribes that became more dominant and the DNA shows that.

How is that effectively not make Neanderthals the same species as human beings?

For a long time, caucasians did not likely mate with pygmies either. Probably not that often today still but we don't say there are 2 different species.

 

[Dinwar]

Parasites can exchange DNA with their hosts. It's plausable (not probable, but plausable) that the DNA got into us through such parasitic genome swapping. Something which could infect both species (not uncommon when they're that close) got into the Neanderthals, then a few generations later got into us, exchanging genes each time. Retroviruses are another pathway. So shared DNA doesn't necessarily mean inter-community mating.

Besides, randman--the species concept isn't as cut-and-dried as you like to make it sound. The boundaries are fuzzy, and it's entirely possible that some groups of both species could successfully mate. There HAVE been fertile mules. The biological species concept is outdated, to say the least.

 

[randman]

Parasites can exchange DNA with their hosts. It's plausable (not probable, but plausable) that the DNA got into us through such parasitic genome swapping. Something which could infect both species (not uncommon when they're that close) got into the Neanderthals, then a few generations later got into us, exchanging genes each time. Retroviruses are another pathway. So shared DNA doesn't necessarily mean inter-community mating.

Besides, randman--the species concept isn't as cut-and-dried as you like to make it sound. The boundaries are fuzzy, and it's entirely possible that some groups of both species could successfully mate. There HAVE been fertile mules. The biological species concept is outdated, to say the least.

I am aware the term species is imprecise and fuzzy. It's ironic coming from you to admit that and yet you still use the term, considering how you have gone on and on about precision in taxonomic classification and other terms.

The reality is there is no reason to still call them a separate species by any definition of the word. It's just a holdover from the time when evos tried to pass them off as more ape-like in search of the missing link.

 

[Damien Evans]

Wouldn't that make Neanderthals more of a human tribe than separate species?

They already were human. The clue is in the genus name, not that I expect you to understand.

 

[Dinwar]

I am aware the term species is imprecise and fuzzy. It's ironic coming from you to admit that and yet you still use the term, considering how you have gone on and on about precision in taxonomic classification and other terms.

Me going "on and on" was me explaining to you what strict taxonomists think. If you read carefullly you'll notice that I haven't given you my thoughts.

The reality is there is no reason to still call them a separate species by any definition of the word. It's just a holdover from the time when evos tried to pass them off as more ape-like in search of the missing link.

Completely off-base, as usual. The reality is that there's EVERY reason to call them a different species--provided one understands what a species IS. They're certainly a different morphospecies (before you argue otherwise, look into the paleontological literature--there's ample precident for calling neandertals a different species), quite likely a different species under the biological species concept (unless you're going to be really strict, in which case roundworms and humans are the same species because we have exchanged DNA), possibly a different genetic species (genetics isn't my area).

A very small fraction of DNA transfer isn't exactly earth-shattering. As I said, there are multiple methods for such a transfer.

 

[quarky]

Well...

I'd like to blame guys like me.Yes; we hit 'that".
Cro-mag babes were hot.
Times were tough.

Mistakes were made.

So sue me?

 

[Perpetual Student]

Neanderthal genes found in all non-African populations -?
Do the Yanomami Indian tribe inhabitants of the Amazon rain forest wear jeans?

 

[Skeptic Ginger]

Parasites can exchange DNA with their hosts. It's plausable (not probable, but plausable) that the DNA got into us through such parasitic genome swapping. Something which could infect both species (not uncommon when they're that close) got into the Neanderthals, then a few generations later got into us, exchanging genes each time. Retroviruses are another pathway. So shared DNA doesn't necessarily mean inter-community mating.

Besides, randman--the species concept isn't as cut-and-dried as you like to make it sound. The boundaries are fuzzy, and it's entirely possible that some groups of both species could successfully mate. There HAVE been fertile mules. The biological species concept is outdated, to say the least.

Not likely. This isn't how it works. If a gene was transfered via a viral vector, it would be a viral gene, not a primate gene.

Microorganisms exchange genes via a couple different mechanisms like you are imagining, but with primates, you are imagining things in a grossly oversimplified way.

 

[Skeptic Ginger]

Wouldn't that make Neanderthals more of a human tribe than separate species?

Homo neanderthalensis is the full name. They are an extinct branch of hominidae. This chart might help you.

Under the current taxonomy (based on genetic rather than behavioral criteria), the term "hominid" refers to members of the biological human family Hominidae: living humans, all human ancestors, the many extinct members of Australopithecus, and our closest primate relatives, the chimpanzee and gorilla.

 

[JoeTheJuggler]

But basically they were a tribe of people that mated with the tribes that became more dominant and the DNA shows that.

Or a handful of individuals in a tribe of modern humans mated with Neandertals.

This is the same issue that confuses Creationists about the Eve hypothesis.

See this: http://en.wikipedia.org/wiki/File:MatrilinealAncestor.PNG

How is that effectively not make Neanderthals the same species as human beings?

I think most anthropologists conventionally treat Neanderthals as a subspecies of humans or as a separate, closely-related species in the same genus. It's 6 of one, half-dozen of the other.

I think the mixing that actually happened was not very significant. Also, I think the differences between modern humans and Neanderthals are pretty striking. Still--subspecies is fine by me if you worry that a species is defined as all the organisms capable of producing fertile offspring. (In plant taxonomy, that'd make you a lumper rather than a splitter!)

 

[Dinwar]

Not likely. This isn't how it works. If a gene was transfered via a viral vector, it would be a viral gene, not a primate gene.

Okay, so the virus is out. The parasite idea may still be viable, however.

Parasite gene transfer occurs in plants.

And in humans and our parasites.

Now, to be clear, I haven't read anything that says that parasites have been observed transfering genes between two species; the idea of H. sapiens and H. neanderthalensis mating is more viable. I'm merely suggesting that it's a possible vector--we know parasites and hosts can transfer genes, and if it's rapid enough I don't see transfer of genes between populations as unreasonable. Perhaps not likely, but there's a lot of species out there, and the two species under consideration are very similar, meaning they likely shared many parasites. My intent was to speculate on an alternative pathway for gene transfer--something that would allow both horizontal transfer AND for the two species to be distinct species by a strict interpretation of the biological species concept.

 

[randman]

Or a handful of individuals in a tribe of modern humans mated with Neandertals.

This is the same issue that confuses Creationists about the Eve hypothesis.

See this: http://en.wikipedia.org/wiki/File:MatrilinealAncestor.PNG


I think most anthropologists conventionally treat Neanderthals as a subspecies of humans or as a separate, closely-related species in the same genus. It's 6 of one, half-dozen of the other.

I think the mixing that actually happened was not very significant. Also, I think the differences between modern humans and Neanderthals are pretty striking. Still--subspecies is fine by me if you worry that a species is defined as all the organisms capable of producing fertile offspring. (In plant taxonomy, that'd make you a lumper rather than a splitter!)

In layman's terms they were just people like anyone else.

 

[dropzone]

The rule of thumb I've used since Neanderthals were supposedly UNrelated, some 20 years ago:

Humans will, er, mate with anybody remotely human. And others further away. That brutish brow ridge could be hot to a Hss female. And a younger Hsn female could do it for a Hss guy, with beer in his belly and sea shells in his pouch.