Just to be clear, since we’re talking about the human/chimp split, the timeframes are more like 5M years, not 50K years. Those times are significantly different in the context of a discussion about the speciation of a large mammal.
Of course. Fifty thousand years was an off-the-cuff number not specific to the human/chimp question. I was reiterating the point that the breeds-together definition of “species” is hard to apply to two samples separated by a large span of time.
Do you know the piano’s on my foot?
True, and not to put too fine a point on it, but the timeframe is still important since virtually all biologist would put the African species of *Homo *at 50K years ago as H. sapiens. There is no problem with fitting skeletal remains from that time period comfortably into either H. neaderthalensis, sapiens, erectus, or floresiensis. And no credible biologist would claim that H. sapiens from 50K years ago would be unable to breed with modern populations today.
And not to be overly nit-picky, but we can’t know definitively without an actual sample. We can make a damned good guess, though.
OK, I give. Can’t find anything to nitpick in that post! 
Based on the simian willingness to screw anything that moves, and plenty of things that don’t, I assume speciation took place before the two populations re-met.
Weeeeeell, that ain’t necessarily true.
I believe the Neanderthals are an example of what I said to Tris. There is no doubt that they and modern humans sprang from a common ancestor but were separated long enough for either complete or partial (depending on who you talk to) special divergence to have occurred. Some researchers have suggested that a remeeting took place before speciation occurred. Whether this was the result of intermarriages or wild parties in the future Portugal and Romania is unclear. This fellow’s study suggests that if the interbreeding between Neanderthals and moderns took place long enough ago, in keeping with the fossil record showing the “extinction” of the Neanderthals 30K years ago, genetic drift could easily account for the loss of all Neanderthal mtDNA in moderns while allowing for some Neanderthal-specific alleles surviving.
This study estimates that 5% of the code carried by modern Europeans, but not by modern Africans, might have come from an ancient “admixture event” (moderns and Neanderthals screwing).
This is quite new, and while I have a lot of respect for Trinkaus, I’d want to see the actual paper before I weighed in. The skull shown in that article is unmistakably Sapiens, and I’d hope they’d have something more than a puzzling shoulder blade to pin their case on.
To be clear, though, I’m talking about what is the general concensus at this time, and we should have some interesting new data very soon when the Neanderthal Genome project is complete (also noted in the article you linked to). The main point I was arguing is that you’d have to go back **much **further than 50k years to find an ancestor who would have trouble breeding with a modern human today. Personally, I think it highly unlikely that Sapiens and Neanderthals couldn’t interbreed, but the data we have now tells us that if they did, they didn’t do much of it.
Yup. Give it a haircut, a shave and a BMW and I guarantee you plenty of today’s population would breed with it.
I think the assumption of the anti-evolutionists which leads to the OP question is:
If a species evolves into something else over time, it replaces the parent species.
This premise is obviously false, since it would require all the critters of a particular species to die off within one generation, leaving only one (or one pair) of survivors to continue the modified gene line.
So evolution makes no such claim. It says that, although replacement can occur, it happens thru extinction. Mutation is more of a branching development. After branching, any branch or the original line or both can become extinct, evolve futher or continue unchanged, but these are independent events.
Yeah, I’m thinking not with H. erectus, though not for lack of trying. (“He’s ugly, but he’s COOL ugly and with a species name like THAT…”)
At least you’re not one of those “absolutely-notists.” And yeah, H. sapiens sapiens was the subspecies with the greater potential for success when it entered Europe and in my second reference Nordborg suggests that H. sapiens neanderthalensis made up only 25% of the new population, small enough to be genetically swamped over the subsequent millenia.
You are quite right. According to Richard Dawkins in The Ancestor’s Tale, the common ancestor of humans and chimps/bonobos lived 5 to 7 million years ago. The gorilla split was around a million years earlier than that.
Orangutans split 14mya, Gibbons 18mya. To get to the common ancestor of humans and what are properly called monkeys - specifically, old world monkeys - you must go back around 25 million years. The new world monkey split was 40mya.
Interesting. Was that his nomenclature? If so, he’s jumping the gun on going back to the decades old idea that Neanderthals were a subspecies. You hardly ever see H. sapiens neanderthalensis anymore-- it’s almost always H. neanderthalensis.
Anyway, it’s hard to imagine two mammalian populations that split only 500k years ago, and who have as long of breeding cycles as we do, that would no longer be interfertile. Chimps and bonobos are interfertile and they split off 2M years ago. They don’t hybridize in nature because their ranges are split by a wide river. But if it does turn out there was significant interbreeding of Sapiens and Neanderthals over an extended period of time, then I guess it would be proper to call Neanderthals a subspecies.
My nomenclature because I’m a stick in the mud who refuses to cede that the Neanderthals belonged to a separate species, using as the species boundary the ability to produce fertile hybrids. Subspecies I’ll grant.
IF the results of these and other pro-interbreeding studies are accurate then I get to lord it over thems what jumped the gun after the mtDNA results and kicked Neanderthals out of the lineage, and there is nothin’ sweeter in science than to be right when a bunch of folks are proven wrong. 
And if they’re wrong I go back to being a laughingstock. It’s a risk I take because the payoff is so great.
Not necessarily. It doesn’t really matter whether they could produce hybrids or even if they did produce hybrids. What matters is whether they commonly produced hybrids. Think of the wolf/coyote analogy. Both have overlapping territories and do sometimes produce hybrids, but we still call them distinct species because hybrids are fairly rare (although there is some indication that the extant red wolf population is a population of such hybrids).
Plus, there are many anthropoligists that are heavily invested in the two species hypothesis. They won’t give in easily! 
Of course this is largely an academic exercise-- the two populations are what they are (or were what the were) regardless of how we choose to classify them.
Is that the only barrier to interbreeding? Because if so, that would seem to suggest that they are one species, after all. For comparison, there were long stretches of time during which H. Sapiens was divided into two populations, which were prevented from interbreeding by oceans, but it’s ludicrous to suggest that Eurasafricans were a different species from Native Americans: As soon as the barrier was overcome, they interbred quite readily. Is the same true of the Pans?
And some (moi sorta included–sorta an anthropologist, not sorta invested) heavily invested in the one species argument. Some of whom (moi) who refuse to accept any redefinition of “separate species” to include populations that can produce fertile hybrids. One must draw the line between species somewhere and if they can produce fertile hybrids they are SUBSPECIES, thankyouverymuch, and anybody who says otherwise is WRONG.
Seems to me that if you’re that wrapped up in only the definition of a word, you’re more of an armchair etymologist than an anthropologist.
Yes and no. I think the creationists believe that this change happened very rapidly (and I’ve never heard a creationist with any knowledge of evolution asking this) . But over enough time, in a single population, the genome can change slowly enough so at the end you have a new species that could not interbreed with the original one - though you would not be able to determine the exact generation where the split got wide enough. Did the original species go extinct? Not really.
There are other scenarios. Perhaps a subpopulation becomes isolated, and evolves due to environmental pressure to become a new species. The barrier could go down, and when moving back to the original area they can out-compete the original species. Perhaps the original one has become a new species also. Perhaps it has gone extinct for other reasons, leaving just the one offshoot.
Speciation doesn’t happen on a set schedule. There could be environmental pressures, like the availability of food during a time which encourages birth during that time, that could move mating season to a different time of the year, which is effectively a speciation event.
Dude, it wasn’t me who stomped all over the standard and venerable definition of “species.” It was those damned splitters who create “species” willy-nilly in order to get girls and to ensure tenure and funding. “Yeah, baby, it may LOOK like a Homo erectus skull to nearly everybody else but do you see that little lump of bone there? It’s a whole new species and I’m gonna name it after YOU, Homo debbia.”