Human and archaic Homo interbreeding?

Yitzhak Rabin

Not sure if this has been done before, but just browsing the net I found a good few articles which seem to suggest that humans may have interbred with both Neanderthal and Erectus. It would certainly explain alot of things such as the evidence which suggests a multiregion origin, like the similar cranium structures of east asians with erectus fossils there.

Neanderthal
From New Scientist
"For the past few years Bruce Lahn, a geneticist at the University of Chicago, has been studying genes potentially involved in human cognition, in particular one called microcephalin. Mutations in microcephalin cause the condition microcephaly, characterised by a small head and various neurological symptoms.
Like many genes involved with brain development, microcephalin has evolved rapidly in humans. In previous studies, Lahn showed that one variant of microcephalin appeared about 40,000 years ago and has since swept through the population, propelled by the power of natural selection. The new variant is found in 70 per cent of living people. "We don't yet know exactly what this variant does or why it is being selected for - it could be something to do with cognition," says Lahn.
The obvious interpretation is that the new version arose 40,000 years ago via a chance mutation in the microcephalin gene. Lahn thinks otherwise. In a paper published last year, he looked at a haplotype within microcephalin. On the basis of sequence differences between the old and new versions of the gene, he concluded that the two are so different that they must have diverged at least 1 million years ago (Proceedings of the National Academy of Sciences, vol 103, p 18178).
This combination of deep ancestry on one level and shallow ancestry on another suggests that something very unusual might have happened. It is as if the new version of microcephalin split off from our evolutionary lineage a million years ago, then jumped back in 40,000 years ago. According to Lahn, that is exactly what happened. By far the most likely explanation, he says, is that the newer version of the gene evolved in a separate species of human - probably Neanderthals - and then entered our lineage through interbreeding.
"These dates roughly correspond to human-Neanderthal divergence 1 million years ago, and the time when they coexisted in Europe 40,000 years ago, which naturally leads to the hypothesis that the new microcephalin gene introgressed from Neanderthals to humans," says Lahn. "Once in the human gene pool, the new variant was selectively favoured and now represents about 70 per cent of the worldwide frequency." In this case multiregionalism cannot explain the pattern: the gene is so strongly favoured by natural selection that if it arose in a subpopulation of humans that was in regular sexual contact with others it would have spread throughout our lineage much earlier."


Although partial sequencing of the Neanderthal genome did not provide evidence of microphaly. That said, the neanderthal genome is far from complete.


There is also the fact that nearderthals had genes for pale skin and red hair aswell, a distincly european trait.



There is also a genetic case to be made for similar interaction between modern humans and homo erectus in asia


New Scientist again.
" [FONT=&quot]One example even tells a possible story of interbreeding between humans and an even more distant ancestor, Homo erectus. The pseudogene RRM2P4 - a remnant of a now-defunct gene - shows even deeper deep ancestry than PDHA1. RRM2P4 comes in two basic types that diverged 2 million years ago - around the same time that Homo erectus first moved out of Africa into Asia. Crucially, one type is found almost exclusively in people of east Asian origin. According to Hammer and Garrigan, the most likely explanation for this deep ancestry and geographical distribution is that the pseudogene evolved in the Asian branch of Homo erectus and introgressed into Homo sapiens (Molecular Biology and Evolution, vol 22, p 189). That event is certainly not ruled out by the fossil record: recent finds suggest that Homo sapiens and Homo erectus coexisted in Asia for several thousand years[/FONT]


If these prove to be true it is very strong evidence for an interbreeding hypothesis, although there could be just environmental factors which lead to similar genes being selected.

Galvasean

Wait 'til Wibbs gets wind of this!

marco_polo

Folllowing on from the draft sequencing announced last last year, the publishing of the full of the Neanderthal genome sequence is imminent according to a new scientist article I was reading recently. So we shall soon have the answer.

On the red hair and pale skin issue it is has been suggested to be a result of a mutation unique to Neanderthals.

http://news.nationalgeographic.com/news/2007/10/071025-Neandertals-Redheads.html

darjeeling

Multiregionalism was hotly debated when we just had fossils. Since we've been getting DNA sequence data, the story has been fairly unequivocal that most if not all genes in all modern humans are inherited from the anatomically modern humans who appeared in Africa around 200 Kya and went on to spread around the world.

We've now got around 7 full Neanderthal mtDNA sequences, courtesy of Svante Paabo's group. They come from across Europe - Spain to Southern Russia - and span perhaps 20,000 years. Despite this, they are genetically similar, and quite different from any of the thousands (tens / hundreds of thousands?) of sequences obtained from modern humans (see e.g. Briggs et al, Science, 2009). This strongly indicates that no Neanderthal mtDNA sequence survived to the present day. Researchers have modelled the demographics of any potential interbreeding between modern humans to see what possible parameters could give rise to this situation, and found that any contribution from Neanderthals must have been very small to non-existent (e.g. Currat and Excoffier, PLoS Biol 2004). Moreover, modern human sequences all form a tightly related group that diverged around 200Kya according to a molecular clock estimate.

In other research, when you survey genetic variation in modern people, as Sarah Tishkoff's group did in their 2009 Science paper on African human genetic diversity, you find a steady decline in nuclear genetic diversity as you get further from Africa, and - Africa aside - very few genetic variations that are exclusive to one region of the globe. You don't seem to see
local increases in genetic diversity that could be attributed to extensive interbreeding between immigrant anatomically modern humans and long-established populations of distantly-related H. erectus.

And as Marco Polo commented above, the fair / red hair mutation found in the Neanderthal MC1R gene described in the 2007 Science paper by Lalueza-Fox et al has not shown up in any modern humans, so red-headedness can't be attributed to hybridisation between Neanderthals and modern humans.

.

Wibbs

darjeeling wrote: »

Multiregionalism was hotly debated when we just had fossils. Since we've been getting DNA sequence data, the story has been fairly unequivocal that most if not all genes in all modern humans are inherited from the anatomically modern humans who appeared in Africa around 200 Kya and went on to spread around the world.

Yes I agree, but and its a big but, relying on DNA evidence for the whole story though fashionable ATM raises some questions as it often doesnt agree with some of the physical archaeology and the bones. EG local populations of moderns show a lot of continuation with local archaics in certain bone structures. Eye socket shape in one. Asian moderns and Asian Archaics have similar shapes, whereas modern and archaic Africans and Europeans do not. As one researcher put it, you could give a forensic pathologist in a crime lab an erectus skull and if you asked him or her the population they would make a damn good stab at it, even with the obvious skull differences. Other problems are archaic features found in moderns. In this case a skull feature, a suprainiac fossa on a modern Sapien human skull(like a ridge on the back of the skull). A feature not found in modern populations, nor in archaic populations before Neandertal, yet all Neandertal skulls so far found have one. http://www.sciencedaily.com/releases/2007/08/070807145140.htm It's not the only example in the bones either.

We've now got around 7 full Neanderthal mtDNA sequences, courtesy of Svante Paabo's group. They come from across Europe - Spain to Southern Russia - and span perhaps 20,000 years. Despite this, they are genetically similar, and quite different from any of the thousands (tens / hundreds of thousands?) of sequences obtained from modern humans (see e.g. Briggs et al, Science, 2009). This strongly indicates that no Neanderthal mtDNA sequence survived to the present day.

It seems it hasn't alright.

Researchers have modelled the demographics of any potential interbreeding between modern humans to see what possible parameters could give rise to this situation, and found that any contribution from Neanderthals must have been very small to non-existent (e.g. Currat and Excoffier, PLoS Biol 2004).

Ok here's a quick and dirty model. Sapien male mates with Neandertal female. They have two sons. The Sapien/Nenadertal sons mate with "pure" Sapien females. Their offspring of either gender will have Sapien mtDNA. No trace of Neandertal mtDNA in the Neandertal grannies grandkids in just two generations. Another scenario. Broadly cultural. Lets imagine that the mating habits when these groups met were very one sided. It could be that Neandertal females werent sexually or culturally attractive to Sapien males, but the reverse may have been more common. That the vast majority of interbreeding took place between Neandertal males and Sapien females. Again you would have no Neandertal mtDNA in the offspring. OK thats an extreme, but possible, or happened enough plus the previous scenario plus the low level of matings in the first place, to have archaic DNA somewhere in our current makeup, but not enough to be obvious?

Moreover, modern human sequences all form a tightly related group that diverged around 200Kya according to a molecular clock estimate.

In other research, when you survey genetic variation in modern people, as Sarah Tishkoff's group did in their 2009 Science paper on African human genetic diversity, you find a steady decline in nuclear genetic diversity as you get further from Africa, and - Africa aside - very few genetic variations that are exclusive to one region of the globe. You don't seem to see
local increases in genetic diversity that could be attributed to extensive interbreeding between immigrant anatomically modern humans and long-established populations of distantly-related H. erectus.

But then you also have the very deep ancestral DNA specific to certain modern populations that are older, in some cases far older than the sapien speciation event. Now they could be local adaptations, but if we believe one clock, we have to come to terms with the age of those dfferences too.

And as Marco Polo commented above, the fair / red hair mutation found in the Neanderthal MC1R gene described in the 2007 Science paper by Lalueza-Fox et al has not shown up in any modern humans, so red-headedness can't be attributed to hybridisation between Neanderthals and modern humans.

The biggest problem with this stuff and paleo archaeology re Human evolution in general is the dearth of evidential material. Its hard enough to find ancient human bones, never mind ancient dna untroubled by contamination ( http://www.sciencedaily.com/releases/2007/10/071012160147.htm ). It seems Neandertals aren't that genetically similar either. They show a higher diversity than moderns and it seems their populations were quite isolated from each other(then again we're very "inbred" compared to most apes). The archaeology also supports this as they didnt seem to trade with other groups. Moderns were trading all over the place and over big distances too. Neandertals were very much more local(though there seems to be some evidence they were picking up this trait from us towards the end). So we may yet find that the particular red hair white skin gene in us came from a single(or localised anyway) event with a particular group of neandertals. A population we dont have a DNA sequence for. AFAIR theres new material coming out from northern Spain. It'll be interesting to see their sequences.

.

darjeeling

Wibbs wrote: »

Ok here's a quick and dirty model. Sapien male mates with Neandertal female. They have two sons. The Sapien/Nenadertal sons mate with "pure" Sapien females. Their offspring of either gender will have Sapien mtDNA. No trace of Neandertal mtDNA in the Neandertal grannies grandkids in just two generations. Another scenario. Broadly cultural. Lets imagine that the mating habits when these groups met were very one sided. It could be that Neandertal females werent sexually or culturally attractive to Sapien males, but the reverse may have been more common. That the vast majority of interbreeding took place between Neandertal males and Sapien females. Again you would have no Neandertal mtDNA in the offspring. OK thats an extreme, but possible, or happened enough plus the previous scenario plus the low level of matings in the first place, to have archaic DNA somewhere in our current makeup, but not enough to be obvious?

This is exactly the kind of thing that the population geneticists have been trying to model. A PlOS Biol 2004 paper by Serre et al (link) found no Neanderthal sequence in 5 early modern humans. Using this finding, the authors applied a very simple model of possible admixture, in which Neanderthals and modern humans are more or less plonked down next to each other and left to breed as they will. The model finds that the absence of any Neanderthal mtDNA in the early sapiens samples is best explained by an introgression of under 25% of Neanderthal genes into the sapiens pool.

More realistic models, used in the Currat and Excoffier paper (link), have sapiens populations pushing progressively into Europe from the east, expanding in numbers as they do so. These models predict that even a very low frequency of Neanderthal x sapiens mating would lead to very high percentages of Neanderthal mtDNA in Europe today. Basically, each cross-breeding event would further dilute the sapiens mtDNAs in the expanding wave of sapiens moving across Europe, until only Neanderthal mtDNAs were left in that wave.

One could also note that in your second scenario - the one where Neanderthal males / early modern human females are envisaged as non-discriminating when it comes to mate choice, whereas human males or Neanderthal females fail to get it on (this seems redolent of James T Kirk and his fondness for sexy female aliens ) - we'd expect to find residual Neanderthal Y chromosomes in Europe. We can find sapiens Y chromosomes that arrived during the Paleolithic, and others that overlaid them in the Neolithic. However, Neanderthal ones ought to look quite different from all of these, reflecting a very old population split. And yet all human Y chromosomes surveyed so far can be collapsed back to give us 'Y-chromosome Adam', who's estimated to have lived around 60,000 years ago.

Some more suggestive evidence for a recent African origin for the great bulk of our genes has come from the hapmap project (papers here and here). Around 3 million single nucleotide polymorphisms (SNPs) were typed in 270 individuals from three continents: Yoruba from Nigeria, Europeans and Chinese + Japanese. The data showed higher diversity throughout the genome in Africa than in Europe or China + Japan. More subtly, Africans showed higher levels of historic chromosome recombination, indicative of a longer population history in Africa. Very few SNP alleles are common in Europe or China/Japan, yet rare in Africa, and only a tiny number of SNPs were fixed for different alleles in different populations. Instead, SNP allele frequencies are highly correlated across continents. This doesn't seem very compatible with substantial genetic input from local archaic hominins in Europe and Asia. Rather, the European and Chinese/Japanese populations look as though they were samplings from an established African population of early modern humans.

Wibbs wrote: »

But then you also have the very deep ancestral DNA specific to certain modern populations that are older, in some cases far older than the sapien speciation event. Now they could be local adaptations, but if we believe one clock, we have to come to terms with the age of those dfferences too.

The date of the most recent common ancestor of a stretch of DNA will vary around the genome. Even with no hybridisation or selection, we'd expect a normal distribution of coalescence times for different genomic sequences. Contrasting modes of selection acting on particular genes may drag them and their neighbours some way from this distribution. From what I've seen so far, there are a handful of reports of very ancient coalescence times for certain fragments of the genome. These seem to be the exception rather than the rule; they may be a relic of a low level of hybridisation between early modern humans and their distant relatives, or they may be due to some other population genetic phenomenon.

Wibbs wrote: »

[...] we may yet find that the particular red hair white skin gene in us came from a single(or localised anyway) event with a particular group of neandertals.

The first I heard about the red-haired Neanderthals was the MC1R gene sequencing paper. If there's no other data suggesting red hair in Neanderthals, then this is speculating that (a) Neanderthals had red hair due to genetic mutations other than the one discovered and (b) that homo sapiens acquired this trait from Neanderthals. It seems simpler to see the modern human red hair trait evolving within the sapiens lineage.

Galvasean

Found an article on ancient human teeth which may relate to this subject:
http://esciencenews.com/articles/2010/01/07/30000.year.old.teeth.shed.new.light.human.evolution

Wibbs

There was also the study into head lice that found IIRC that there was strong evidence for close bodily contact between erectus and ourselves in Asia. Now this could be explained by possible cannibalism, but sexual contact is just as likely.

The problem is there is evidence in the bones(and in distrubution and evolution of stone tools). Neandertal features in moderns for one. It could be argued there is some evidence of modern features in Neandertals towards the end. They did get less robust, though that could simply be parallel evolution too. There are further strange ones too. The earliest moderns in australia look more modern than recent australians. Less robust skulls etc. Though again they could be local adaptations to a very extreme climate. Another one as I mentioned is local morphology staying static over time and over archaics and moderns. The teeth is one example. There is a large proportion of Asians today that have shovelled incisors. A feature very rare elsewhere. Yet is found in archaic asian populations in the same frequency(but not in archaics elsewhere).

In tools the classic is the handaxe. It was very fashionable in Africa yet didnt reach asia until well after the proposed out of Africa migration. How did this happen where a very handy technology disappears as moderns move into an area? It would stand to reason they would bring said technology with them. They did in Europe. It makes little sense as archaeologists would tell you. There's a gap of continuity between africa and asia.

While DNA evidence is compelling it's also as I said fashionable as a catchall technique at the moment. It's a damn good one, but there are issues with it. Genetic clocks can be unreliable, plus the archaic material we have is minimal. According to wikipedia(I know ) in the case of Neandertal Modern comparisons, "the largest example of sequenced Neanderthal nuclear DNA comprised 1 million base pairs compared to a human nuclear genome size of roughly 3 billion base pairs. This amounts to a comparison of only 0.033% of the genomes". Technical term may be "feck all".

Torakx

Wibbs wrote: »

There was also the study into head lice that found IIRC that there was strong evidence for close bodily contact between erectus and ourselves in Asia. Now this could be explained by possible cannibalism, but sexual contact is just as likely.

The problem is there is evidence in the bones(and in distrubution and evolution of stone tools). Neandertal features in moderns for one. It could be argued there is some evidence of modern features in Neandertals towards the end. They did get less robust, though that could simply be parallel evolution too. There are further strange ones too. The earliest moderns in australia look more modern than recent australians. Less robust skulls etc. Though again they could be local adaptations to a very extreme climate. Another one as I mentioned is local morphology staying static over time and over archaics and moderns. The teeth is one example. There is a large proportion of Asians today that have shovelled incisors. A feature very rare elsewhere. Yet is found in archaic asian populations in the same frequency(but not in archaics elsewhere).

In tools the classic is the handaxe. It was very fashionable in Africa yet didnt reach asia until well after the proposed out of Africa migration. How did this happen where a very handy technology disappears as moderns move into an area? It would stand to reason they would bring said technology with them. They did in Europe. It makes little sense as archaeologists would tell you. There's a gap of continuity between africa and asia.

While DNA evidence is compelling it's also as I said fashionable as a catchall technique at the moment. It's a damn good one, but there are issues with it. Genetic clocks can be unreliable, plus the archaic material we have is minimal. According to wikipedia(I know ) in the case of Neandertal Modern comparisons, "the largest example of sequenced Neanderthal nuclear DNA comprised 1 million base pairs compared to a human nuclear genome size of roughly 3 billion base pairs. This amounts to a comparison of only 0.033% of the genomes". Technical term may be "feck all".

apologies for my ingorance but can you explain in layman terms that last posts final conclusion.
is that hinting that we did not come from neanderthals alone? or at all?
alot of this thread is well over my head hehe.

Wibbs

Basically I'm saying the jury is still out on whether we mixed or not. I reckon we did and the genetic evidence has a lot of holes in it when compared to other evidence. Others disagree

Yitzhak Rabin

Torakx wrote: »

apologies for my ingorance but can you explain in layman terms that last posts final conclusion.
is that hinting that we did not come from neanderthals alone? or at all?
alot of this thread is well over my head hehe.

I might be getting this wrong, and anyone can jump in and correct my mistakes...

He is saying that at the moment there is evidence which points towards us not having interbred with any other species, but the evidence is not yet conclusive because we don't have enough of it. The DNA of extinct hominids is extremely hard to come by.

(Edit: sorry Wibbs, didn't mean to clarify what you said for you, I responded before I saw your post!:D)

marco_polo

Researchers from the University of New Mexico have performed a genetic analysis of nearly 2,000 people from around the world. They suggest that their results are best explained by extinct species interbreeding with the ancestors of modern humans twice, once around 60,000 years ago in the eastern Mediterranean and, more recently, about 45,000 years ago in eastern Asia.

I think the proposed date of the first interbreeding are particularily interesting, because the time and location are fairly good match for the timelines and locations proposed in varients of the single migration 'Out of Africa' theories.

Perhaps it opens up the possibility of both camps being partially correct?

http://www.nature.com/news/2010/100420/full/news.2010.194.html

The researchers arrived at that conclusion by studying genetic data from 1,983 individuals from 99 populations in Africa, Europe, Asia, Oceania and the Americas. Sarah Joyce, a doctoral student working with Long, analyzed 614 microsatellite positions, which are sections of the genome that can be used like fingerprints. She then created an evolutionary tree to explain the observed genetic variation in microsatellites. The best way to explain that variation was if there were two periods of interbreeding between humans and an archaic species, such as Homo neanderthalensis or H. heidelbergensis.

"This is not what we expected to find," says Long.

Using projected rates of genetic mutation and data from the fossil record, the researchers suggest that the interbreeding happened about 60,000 years ago in the eastern Mediterranean and, more recently, about 45,000 years ago in eastern Asia. Those two events happened after the first H. sapiens had migrated out of Africa, says Long. His group didn't find evidence of interbreeding in the genomes of the modern African people included in the study.

The researchers suggest that the population from the first interbreeding went on to migrate to Europe, Asia and North America. Then the second interbreeding with an archaic population in eastern Asia further altered the genetic makeup of people in Oceania.

The talk at the anthropology meeting caught the attention of many researchers, some of whom have been trying to explain puzzling variations in the human genome. "They are onto something," says Noah Rosenberg, an anthropological geneticist at the University of Michigan in Ann Arbor, who heard the talk.

In other news the full Neantherthal genome is on the way ...... any day now.

darjeeling

marco_polo wrote: »

Researchers from the University of New Mexico have performed a genetic analysis of nearly 2,000 people from around the world. They suggest that their results are best explained by extinct species interbreeding with the ancestors of modern humans twice, once around 60,000 years ago in the eastern Mediterranean and, more recently, about 45,000 years ago in eastern Asia.

I was hoping to have a look at the paper, but it doesn't seem to have been published yet - only the report of a conference talk.

marco_polo wrote: »

In other news the full Neantherthal genome is on the way ...... any day now.

Yes, any day .......

marco_polo

darjeeling wrote: »

I was hoping to have a look at the paper, but it doesn't seem to have been published yet - only the report of a conference talk.



Yes, any day .......

Didn't notice that presumed there was an accompaning paper.

I'm nearly as bad as the Daily Telegraph for jumping the gun

Wibbs

Ohhhh me likey

marco_polo wrote: »

Researchers from the University of New Mexico have performed a genetic analysis of nearly 2,000 people from around the world. They suggest that their results are best explained by extinct species interbreeding with the ancestors of modern humans twice, once around 60,000 years ago in the eastern Mediterranean and, more recently, about 45,000 years ago in eastern Asia.



I think the proposed date of the first interbreeding are particularily interesting, because the time and location are fairly good match for the timelines and locations proposed in varients of the single migration 'Out of Africa' theories.

Perhaps it opens up the possibility of both camps being partially correct?

I've always been of the opinion that the middle path was the way to go. Complete multiregionalism I don't buy, as much as I dont buy the complete out of Africa notion. It had to be more fluid than that. The evidence in the fossils and tools seemed to suggest some continuation of archaic traits in moderns. It also explains how you see genes in local moderns that are far older than the proposed later out of africa event. It explains the evolution of the head louse too(it would be interesting to see if the african head louse is different to the asian. If not, worms can opened ).

The eastern Mediterranean dates like you say are interesting. Especially as we have sites in israel where sapiens and neandertals were living in very close proximity for long periods of time. They must have gotten busy enough times to have the possibility of these archaic markers still present? I'd imagine a one off event would have died out?

In Asia it's even more weird. Neandertals were a lot closer to us than Erectus, both in genetic time and likely behaviour. Now the view of Erectus as being a bit slow has got some knocks recently with some evidence of long sea voyages and some evidence of cultural ideas, but they would have been in Asia for at least a million years before we show up and pretty different. If we could mate successfully with each other that's amazing given the genetic gap in time. Then again like I mentioned before, wolves can cross with coyotes and they're further apart.

I'd love to see further study into native australians DNA(the above team seem to suggest interesting results from oceania). The puzzle that the earliest australians had less archaic features than later and modern australians is interesting. It seems as well from DNA from mungo man that his line died out. So maybe the first aussies went straight from africa. Pretty much ran along the coast middle east, india SE asia and across into australia about 60,000 years ago and didnt get into hanky panky with erectus on the way. Then another migration occurred later on from asia which had the earlier human mixing going on, which brought along these more archaic features, then interbred with or even largely replaced the folks that were there already? Maybe there was even more recent migrations? The dingo seems to have split from other asian dogs 10,000 odd years ago and its unlikely they swam to Oz on their own. Modern native aussies may be a good place to look as they were pretty isolated(or maybe not?) until 200 odd years ago.

Ash.J.Williams

Wibbs wrote: »

Basically I'm saying the jury is still out on whether we mixed or not. I reckon we did and the genetic evidence has a lot of holes in it when compared to other evidence. Others disagree

Judging by the heads on people where I am from I would say mixing was rampant!!!

Wibbs

Another link courtesy of a fellow boardsie http://www.newscientist.com/article/dn18869-neanderthal-genome-reveals-interbreeding-with-humans.html?page=1 Thanks Thaed

Yitzhak Rabin

Wibbs wrote: »

Another link courtesy of a fellow boardsie http://www.newscientist.com/article/dn18869-neanderthal-genome-reveals-interbreeding-with-humans.html?page=1 Thanks Thaed

I knew it!! It was just too plausible not to have happened!

marco_polo

Sciencedaily article here:

http://www.sciencedaily.com/releases/2010/05/100506141549.htm

Of course I never doubted you Wibbs*

Well maybe a little bit.

I had an reasonably open mind on the subject, but I suppose it is a little bit of a surprise after the initial mDNA results.

Reading this I was reminded of a quote by Stephen Hawking saying that that most interesting scientific outcome of the LHC would be if be if the expected Higgs boson is not discovered, I think evidence turning out in favour interbreeding is also the more exciting scientific outcome in this case.

Also it seems calling someone a Neanderthal can no longer be classified as an insult.

Wibbs

And for my next prophecy? *stares into crystal ball*...

We'll discover that we got pale skin from Neandertals, not a novel gene change of our own. Why? Well its been believed that we became paler because of an adaptation to higher latitude living, over the last 40,000 years. Make sense, but... Consider the native Tasmanians. They lived in a similar higher latitude on the other side of the world for nearly 60,000 years and they were among the darkest people in the entire human species. Why didnt they adapt?

We'll discover we got jiggy with erectus outside Africa too. In Asia in particular.

So how would we go about looking for this? I would look at outlier populations still extant today. Good examples; the various "african" peoples outside Africa. IE the andaman islanders are one example. They have genes going back 60,000 years. African genes. I'll put money down that they wont have these earlier hominid genes. There are other examples of so called "negrito" populations throughout Asia that tend to run along the southern coasts. I'd look at building a gene map of Native Australians and compare them to what little we have of Tasmanian DNA. Compare them to extracted DNA of older populations. Ditto in Papua New Guinea. Then do same with isolated populations in Asia and into north Asia. I'd be looking at the isolated groups in the US too. Peoples like the Fuegians at the bottom tip of south america.

So my take is this. Archaic humans in Europe and Asia. The first Africans(us) leave and run along the southern asian coast, fishing and eating along the way quite quickly getting all the way to New Guinea, Australia and Tasmania, while leaving the Asian interior to the archaics. Leaving pockets and echos of that migration today.

Then there is a second or contemporary population of Africans to them that head into the interior of Europe and asia, after staying put in the middle east long enough to get jiggy with the Neandertals at their southernmost range. They move into europe, getting further jiggy with the locals and picking up handy mutations like pale skin. The others head off into Asia and get busy with erectus there. This shows in the localised continuation of some erectus features into the moderns in the area. Africans show this local continuity too, but we came from african erectus in africa anyway so...

These central asian folks then migrate into the existing homelands of the first african lads and lasses and get busy with them. This explains why Native australians start off looking like more gracile humans(like andaman islanders), then become much more robust with what may be echoed erectus features(heavier boned skulls and browridges) which came along with the later mirgation from asia who had gotten busy with the archaics there and then become more gracile again, with further later migrations(native australians today can still exhibit much larger browridges and more robust skulls than other populations). Ditto for populations like Papuans.

In Europe the populations likely remain more cut off with smaller populations due to ice ages etc and there are only one or two major moves in until relatively recently. In the Americas, I suspect the first African lads made it maybe 20,000+ years ago and got all the way to the tip of south america, where remains of ancient skulls may show more african traits than the later Asian migrations which followed. On the eastern seaboard the presence of the X haplogroup although rare, but never found in the west suggests a european migration at some point, though likely small. Then the main thrust through north asia brought the bulk of modern native genes into the mix.

My take anyway.

Wibbs

PS Please, please please can I ask all your sufferance and let me do a little dance singing "na na na na na, I told ya so!"

Wibbs

Looking more at the study it seems the Neandertal DNA was only taken from one group in Croatia. That's a very small sample and its not even near to the full genome either. How lucky would we have to be to find links on the first try? Given the range of them as a species, I reckon the more DNA sequences we get the more links we'll see. I'm so hoping with the areas of melt in the northern permafrost that we may get a frozen example. I further suspect that if that ever happened without our cultural bias imagining them over the years,(from shambling ape to stocky bloke down the road) we may be surprised how more or less "human' they look. I suspect more human, especially the later ones.

darjeeling

I think the interesting question was always how much, if any, of our genome comes from Neanderthals. The mtDNA results said none to a very small amount. The first nuclear genomic data gave a similar story. Now this new study says we get just one to four percent from Neanderthals.

Comparing modern human genomes of people from France, China and Papua New Guinea with the Neanderthal showed that all had similar levels of Neanderthal genetic input, whereas Yoruba Africans had none. The authors think this means that modern human-Neanderthal mixing happened early, before the expansion of humans across Eurasia.

The actual paper is free to read here.

marco_polo

Completely missed this study which appeared in the same issue of science, which puts the number of differences in coding protein sequences between Humans and Neanderthals at a paltry 88 (most of which are one single amino acid differences). Having initially identified 1000 differences when compared against the reference human genome, once all modern variation is accounted all but 88 diferences were eliminated.

http://www.sciencedaily.com/releases/2010/05/100506141559.htm

Hannon's team applied its focused sequencing method on those areas in the Neandertal sample obtained from Dr. Pääbo, and, after several rounds of refinement, they arrived at the number 88: they found only 88 changes in Neandertal protein sequences compared with the modern human. Hannon calls this number "astonishing."

At an early stage of the study, the team identified many more protein differences -- about 1000 -- between modern man and the specific Neandertal individual sampled, a male who died about 49,000 years ago in a cave called El Sidrón, in Spain. But that initial figure was based on comparing the Neandertal sequence to that of the modern human reference genome. When the teams incorporated into their calculations variations in the modern human code that they catalogued in 50 individuals from a range of modern ethnic groups, the number of human-Neandertal protein differences dropped from over 1000 to only 88.

Although Hannon says it will be important to study the functional role of the 88 proteins, he expects that many may prove "neutral," functionally. These would be changes in the genetic code that do not issue in any difference in the function of the associated proteins. If even more human genome samples -- say, from 500 contemporary individuals rather than 50 -- were included in the comparison, the number of differences might drop again, Hannon believes. And if additional Neandertal samples were factored into the comparison, he says, "it's possible that the number of differences could approach zero."

Also with a full paper available: http://www.sciencemag.org/cgi/reprint/328/5979/723.pdf