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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: 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.