Hints of an early exodus of modern humans from Africa may have been detected in living humans.
People outside Africa overwhelmingly trace their descent to a group that left the continent 60,000 years ago.
But the results suggest this early wave of Homo sapiens all but vanished, so it does not drastically alter prevailing theories of our origins.
And two separate studies in the academic journal Nature failed to find the signal of a later movement.
Writing in Nature , Luca Pagani, Mait Metspalu and colleagues describe hints of this pioneer group in their analysis of DNA in people from the Oceanian nation of Papua New Guinea.
The researchers examining the DNA in Papua New Guinea found the traces of the earlier migration by subtracting the DNA from the more recent migration out of Africa 60,000 years ago and the DNA from the Denisovans.
(Score: 2, Insightful) by RamiK on Friday September 23 2016, @01:07AM
A species is defined as the largest group capable of interbreeding. So, since races are senseless made-up voodoo with less biological significance then one breed of chicken versus the next, you're left with subspecies. But, some idiot decided that connotes inferiority so you can't use that...
And so, you end up with these sort of articles where no terms are used. Each sentence, a linguistic leap. Each paragraph, a mine bending effort at grammar gymnastics.
A tip for the kids: If choosing a career in biology, geology or climatology, make sure to excel at essay writing.
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(Score: 4, Informative) by Arik on Friday September 23 2016, @01:42AM
Can you point out any place where using one of those terms would be accurate? I don't see one. The two different 'waves' of humans they are postulating would not have been different races or subspecies from each other, but very close relatives deriving from the same ancient population at different points in time.
These hypothetical two-waves of migration, if they existed at all, would have been very close relatives, almost indistinguishable. And frankly I'm very skeptical of the assumptions behind this analysis. It's extremely unlikely that modern humans have any DNA that actually derives from Denisovans or from Neanderthals, despite the flood of articles claiming otherwise. Yes, there are some genes found in common, but somatic DNA is simply not a reliable way to trace ancestry, and interbreeding is not the only or best way to explain those common genes. The evidence is better explained by parallel evolution. Both races came from a common ancestor, and shared the large majority of their DNA code with each other *through that common ancestor*. Specific traits that were selected for among the Neanderthal and Denisovans was also selected for among modern Humans when they migrated to the same regions.
I've been paying attention to this for decades and I have yet to see a single piece of hard evidence for neanderthal-human offspring. Not even proof that it was physically possible, let alone that it happened.
If laughter is the best medicine, who are the best doctors?
(Score: 2, Informative) by khallow on Friday September 23 2016, @02:03AM
These hypothetical two-waves of migration, if they existed at all, would have been very close relatives, almost indistinguishable.
Except of course for genetic tests which is what they used.
It's extremely unlikely that modern humans have any DNA that actually derives from Denisovans or from Neanderthals, despite the flood of articles claiming otherwise.
Because feelings? There's plenty of real world examples of genetic crossing between near species. Frankly, I thought the absence of genetic crossover between human species was the real unlikely part.
I've been paying attention to this for decades and I have yet to see a single piece of hard evidence for neanderthal-human offspring. Not even proof that it was physically possible, let alone that it happened.
Odds are good that we'll have neanderthals within half a century. Then we can determine just easily they breed with homo sapiens.
It's worth noting here that we've had significantly shifting narratives of the origin of humanity over the past century. So yes, I believe there is a very good chance that we're still missing huge parts of the history as well as being wrong in a variety of ways. perhaps even in the ways you state. But that state of ignorance isn't improved by merely asserting things which have no basis in fact.
(Score: 2) by Arik on Friday September 23 2016, @03:26AM
Can I prove it never happened? Obviously not, the notorious problem of proving a negative.
But I would expect to see evidence of it, and I don't. There are several areas where Neanderthal and CroMagnons lived in close proximity for 10s of thousands of years, and people went through those skeletons back in the 80s expecting to find evidence for it - a single individual in one community or another with an intermediate phenotype. You'd really think you'd find one. No one has.
I was excited when I first heard about these DNA tests. Finally! Proof of what I suspected so strongly all along.
Then I went and actually read deep enough to find out what they were testing, and I was very disappointed. This is the old meme that anyone with blue eyes must 'have some white in them' only dressed up in more respectable clothes.
As I said, there's a far more plausible explanation for the results. The same genes inherited from the common ancestor changed in the same way in response to the same environmental stimuli. Parallel evolution.
If laughter is the best medicine, who are the best doctors?
(Score: 3, Informative) by khallow on Friday September 23 2016, @04:28AM
As I said, there's a far more plausible explanation for the results. The same genes inherited from the common ancestor changed in the same way in response to the same environmental stimuli. Parallel evolution.
Which isn't actually a more plausible explanation. Genetic drift is a thing here and there are several examples of drift even among closely related species in identical niches (such as various subspecies of Abert's squirrel [wikipedia.org] or the huge variety of Madagascan lemurs [wikipedia.org]). And selection goes beyond environmental stimuli (which despite your claims, may have been significantly different) since they probably had different cultural selection pressures.
(Score: 2) by Arik on Sunday September 25 2016, @03:56PM
Nah, scratch that, even better, why is it that these studies that show positive results always turn out to be testing areas that are known to be unreliable for determining ancestry, while the studies that compare only appropriate sections show (to the best of my knowledge) uniformly negative results?
I'm not claiming I'm read everything published on the subject, by any means, if you think I've missed something give me a link. But I look for something like this: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2602844/
If laughter is the best medicine, who are the best doctors?
(Score: 2) by gringer on Sunday September 25 2016, @11:16PM
If there was interbreeding, then why is there not a single convincing example of an intermediate phenotype?
What do you mean by an intermediate phenotype? We have a hard enough time phenotyping people for specific, known traits. It may just be very unlikely that we'd see an intermediate phenotype for what it is. As one example, consider how long it has taken us to acknowledge that [at least some] dinosaurs had feathers.
It's not obvious what a particular genetic change would do to the body. It seems like you're asking for an intermediate change in physical appearance, but the variation in appearance in humans is quite large and possibly overlapping with the ancestral populations. Can you give a convincing example of an ancestral phenotype that is not in the present-day population and/or what an intermediate phenotype would look like?
Ask me about Sequencing DNA in front of Linus Torvalds [youtube.com]
(Score: 1) by Arik on Monday September 26 2016, @01:57PM
You've obviously not spent much (or any?) time studying the skeletons of these two species.
There are many very clear and large differences between the two just at the level of gross anatomy. The bones are different shapes, different sizes in relation to each other, and include bits that a modern human would not have. There are grooves where a modern human would have no grooves. They had a superorbital torus above their eyes, protruding bones around the nose, a bony labyrinth shaped very differently from ours. Their mental foramen is strikingly oversized compared to ours, the pelvis is shaped differently, the thigh bones are shaped differently....
People that get 'you look like a neanderthal lol' can have a handful of features that lead to that look - a short stocky guy with a sloping forehead and a lot of hair might get it, but the resemblance is only superficial and a cursory examination immediately dispells it.
If laughter is the best medicine, who are the best doctors?
(Score: 1) by Arik on Sunday September 25 2016, @09:01PM
The mtDNA work indicated MRCFA at 520kya-800kya and the Y-dna indicates MRCMA at 447kya–806kya (95% on each.)
If there's real interbreeding in play here, rather than similar genetics inherited from a common ancestor changing in the same way under similar stimuli, I would expect to see some indication of it in studies like I have cited, ones that focus on the correct parts of the genome to answer this sort of question, and I haven't seen that.
If laughter is the best medicine, who are the best doctors?
(Score: 1) by khallow on Tuesday September 27 2016, @11:05PM
If there's real interbreeding in play here, rather than similar genetics inherited from a common ancestor changing in the same way under similar stimuli, I would expect to see some indication of it in studies like I have cited, ones that focus on the correct parts of the genome to answer this sort of question, and I haven't seen that.
Why would you expect to see such evidence of interbreeding? It's pretty clear that it would at best be rare. That's a long time for such a lineage to survive and it would naturally be swamped by homo sapiens. If a mated pair produced a bunch of offspring (which might be a difficult thing to achieve), there would right away be a halving of people carrying the Y chromosome or the mitochondria DNA of the respective Neanderthal parent. And they would start in a population of tens of thousands of homo sapiens.
And what happens, if researchers just haven't yet found people who carry such genes (them being rare and all)?
(Score: 1) by Arik on Wednesday September 28 2016, @03:50AM
Where I have heard that line before? Oh yeah Kent Hovind.
Look, it's true, the lack of any good evidence for interbreeding does not, strictly speaking, prove that no interbreeding ever happened. No one can prove that it didn't happen, but that doesn't mean it's likely. You can't disprove the flying spaghetti monster either.
Look, I posted this further up the thread but in case you missed it, there were communities in close proximity for 10s of thousands of years. If it was physically possible for them to interbreed, everything we know about primate ethology indicates it would have happened, frequently. Yet if it did happen at all, it was so infrequent that no clear trace of it remains.
Occams razor demands that we consider the possibility it simply was not possible.
If laughter is the best medicine, who are the best doctors?
(Score: 1) by khallow on Wednesday September 28 2016, @05:50AM
Absence of evidence is not evidence of absence eh?
There is no true absence of evidence here.
Look, it's true, the lack of any good evidence for interbreeding does not, strictly speaking, prove that no interbreeding ever happened. No one can prove that it didn't happen, but that doesn't mean it's likely. You can't disprove the flying spaghetti monster either.
You already admitted they have weak evidence for interbreeding.
Look, I posted this further up the thread but in case you missed it, there were communities in close proximity for 10s of thousands of years. If it was physically possible for them to interbreed, everything we know about primate ethology indicates it would have happened, frequently. Yet if it did happen at all, it was so infrequent that no clear trace of it remains.
Occams razor demands that we consider the possibility it simply was not possible.
No, Occams razor is what you actually concluded. That interbreeding was so infrequent that no clear trace remains not that it was not possible.
(Score: 4, Funny) by Bogsnoticus on Friday September 23 2016, @07:02AM
> "I have yet to see a single piece of hard evidence for neanderthal-human offspring."
Pay attention to the doormen at nightclubs, and you'll find your evidence.
Genius by birth. Evil by choice.
(Score: 4, Insightful) by Runaway1956 on Friday September 23 2016, @02:17AM
"less biological significance then one breed of chicken versus the next,"
I think that the difference between races is precisely the same as the difference between breeds of chicken. Or dog, or cat, or whatever.
And, for the sake of political incorrectness - there are measurable differences between the various breeds of animal. One chicken has a meatier breast, one race of man has a meatier ass. There are differences between the breeds. I'm so tired of attempts to ignore or hide the fact that we do have differences. Difference can be good. Monocultures are bad. What is there to discuss?
You will note that I've not indicated that any subspecies of man is in any way inferior to another subspecies. I've merely noted that there are differences, just as there are differences between subspecies of any other animal. We may literally "look down on" a Pygmy tribesman, that doesn't mean we have to "look down on" him figuratively.
(Score: 0) by Anonymous Coward on Friday September 23 2016, @01:52PM
You will note that I've not indicated that any subspecies of man is in any way inferior to another subspecies. I've merely noted that there are differences
You're correct.
The thing is that some people with an ax to grind take a similar strategy or go into the "I'm just asking [disingenuous] questions" strategy. This is why some people will jump on comments like this with irrational ferver because they assume the parent was disingenuous (not a bad assumption for this topic) and they "know" that it is just a lead-in to the typical racist shit.
Unfortunately, the community of this site (or anywhere, really) are unable to have productive discussions on this kind of topic.
(Score: 2) by RamiK on Friday September 23 2016, @02:03PM
Not really. There are no meaningful evolutionary pressures on humans. We're like alligators or big cats in the sense that once you hit the apex predator leagues you don't have any reason to change.
Skin color... Nose bridges... eye forms... If you put all the variance on a binary tree, the differences will be even lower then the difference between a farm animals.
You can quantify it all when looking how little difference there's between house cat and street cats breeds versus the big differences between dog races. Humans variance is much more like cats in the way it's all very superficial selection. Some skin colors here... Some fur there... A different nose bridge... Curly hair... A bit calmer... A bit stronger... But very little to do with meaningful adaptation that can't be picked up under a couple of generation of real pressure.
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(Score: 1, Funny) by Anonymous Coward on Friday September 23 2016, @01:15PM
No doubt, 60,000 years ago, riots, vandalism, looting, and crime "encouraged" emigrants to leave for more civilized areas.