# Human Speciation **URL:** \ **Category:** Factual Questions\ **Created:** [December 2, 2011, 6:17pm UTC](https://boards.straightdope.com/t/human-speciation/604866 "2011-12-02T18:17:18Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [December 3, 2011, 4:15pm UTC](https://boards.straightdope.com/t/human-speciation/604866/21 "2011-12-03T16:15:11Z")
> [@The\_Flying\_Dutchman](#): > > Eye colour is a bad example for differentiating populations. It just hasn’t been a factor in discrimination in the past. Plenty of whites do not have blue eyes. In the context of the OP’s question, it’s a very good example. > [@](#): > > Given the global village we now live in I believe that eventually the “racial” distinguishing characteristics we see today will disappear, but it will take a long long time. No. Highly unlikely except in the scenario I mentioned. > [@](#): > > Racist countries , particularly in the far east will be the last holdout of the “racially pure”. Geography created differentiating morphology, and modern transportion and communication has overcome geography. We will come to a point where kinky hair in the general population will be viewed much like ginger hair is today in the white population. Again, highly unlikely, given the large and growing population of sub-Sahara Africans with what you are calling “kinky” hair. > [@](#): > > Its now known that eastern USA wolves comingled with coyotes long ago and it was only discovered through DNA. They are pretty well indistinguishable from each other within the sub species. I have no idea what that even means, much less how it applies to the OP’s question. **Jonathan** : Agreed. I consider it a necessary, but not sufficient condition. Sorry if that wasn’t clear. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [December 3, 2011, 4:30pm UTC](https://boards.straightdope.com/t/human-speciation/604866/22 "2011-12-03T16:30:11Z")
Consider realtively isolated populations - The Indians of the Andes are moderately well adapted to high altitudes. I recall reading about a tribe (Chile?) that had the various adaptions like lung function to survive in one of the higher altitude settlement areas. This in about 14,000 years since first arriving. The Natives of the Americas were relatively separated and isolated by geography for about 14,000 years. Similarly, the aborigines of Australia were isolated for about 40,000 years. Both exhibit rather distinctive appearance; the aborigines, moreso. However, neither group had any problems with breeding with Europeans, semi-isolated at the other extreme end from these groups. Again, interfertility may be a read herring as others have pointed out. After all, we have mules; occasionally we have ligers in the news. Eskimos allegedly left their dogs out to be fertilized by wolves. There’s speculation sapiens sapiens and neaderthals interbred, and the results were fertile. I’ve seen some debate about the wolves, coyotes, etc. which suggests that what was once thought of as a distinct species of wolf is simply a variant with different coulouring. So “species” is a vague concept. Considering the variations in horses or dogs, which are each still one species, is even significant morphology difference a good indicator? ---
**Author:** ![Jonathan\_Chance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jonathan_chance/32/701_2.png) [@Jonathan\_Chance](https://boards.straightdope.com/u/Jonathan_Chance)\ **Post date:** [December 3, 2011, 4:49pm UTC](https://boards.straightdope.com/t/human-speciation/604866/23 "2011-12-03T16:49:28Z")
> [@John\_Mace](#): > > **Jonathan** : Agreed. I consider it a necessary, but not sufficient condition. Sorry if that wasn’t clear. Which isn’t to say it can’t have that sort of result. Look at cheetah’s, after all. Somewhere around 10k years ago they had one HELL of a bottleneck, apparently. Now all cheetahs are sufficiently similar that skin grafts from one may have no rejection on an entirely different animal. Toss in their similarity in appearance and it appears that 10k years is not enough to bring diversity to a specialized species following a bottleneck. So what may lead to human diversity isn’t a natural thing but our own plasticity. Our ability to survive in almost any niche gave the opportunity to have different adaptations, both visible and not, where cheetahs did not. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [December 3, 2011, 4:55pm UTC](https://boards.straightdope.com/t/human-speciation/604866/24 "2011-12-03T16:55:16Z")
> [@Jonathan\_Chance](#): > > Which isn’t to say it can’t have that sort of result. > > Look at cheetah’s, after all. Somewhere around 10k years ago they had one HELL of a bottleneck, apparently. Now all cheetahs are sufficiently similar that skin grafts from one may have no rejection on an entirely different animal. Toss in their similarity in appearance and it appears that 10k years is not enough to bring diversity to a specialized species following a bottleneck. > > So what may lead to human diversity isn’t a natural thing but our own plasticity. Our ability to survive in almost any niche gave the opportunity to have different adaptations, both visible and not, where cheetahs did not. You have to be careful when talking about similarity of appearance. We have evolved to be highly sensitive to human facial variations. I don’t know if cheetahs use visual signals to differentiate individuals or if they use scent more. Perhaps cheetahs are highly attuned to subtle variations in the spot pattern in their fur that we aren’t. ---
**Author:** ![Jonathan\_Chance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jonathan_chance/32/701_2.png) [@Jonathan\_Chance](https://boards.straightdope.com/u/Jonathan_Chance)\ **Post date:** [December 3, 2011, 5:05pm UTC](https://boards.straightdope.com/t/human-speciation/604866/25 "2011-12-03T17:05:51Z")
Oh, that may be so. I sort of figure it is under the ‘only they know the difference’ rule. But cheetahs really are astonishingly similar at a large variety of levels down to genetic. So the diversity just isn’t there yet at 10k years out. I, as a layman, welcome guidance but have always chalked it up to the specialization of the cheetah’s niche. There’s simply been little pressure or ability to adapt to another role or environ so there’s been little change. Really, it’s like every potential mate is first cousin or closer over there. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [December 3, 2011, 5:10pm UTC](https://boards.straightdope.com/t/human-speciation/604866/26 "2011-12-03T17:10:26Z")
Yes, cheetahs are extremely inbred. But I don’t think they make a good model for a human population. They are specialists and we are extreme generalists. It would take a very different, hostile environment to keep us inbred like that for 10k years. ---
**Author:** ![Gary\_Robson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gary_robson/32/3448_2.png) [@Gary\_Robson](https://boards.straightdope.com/u/Gary_Robson)\ **Post date:** [December 3, 2011, 6:34pm UTC](https://boards.straightdope.com/t/human-speciation/604866/27 "2011-12-03T18:34:50Z")
> [@Naxos](#): > > Racist much? > > I get questions like yours all the time. > > The sewer of humanity has no limit. Anyone is glad to join at any time. [Moderator Note] Over the top for GQ much? The OP asks a perfectly valid question, and your response is entirely inappropriate for this forum. Dial it back. [/Moderator Note] ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [December 3, 2011, 7:12pm UTC](https://boards.straightdope.com/t/human-speciation/604866/28 "2011-12-03T19:12:05Z")
As for another part of the OP, some rural parts of areas like highland Scotland, Ireland, Iceland, lapland etc. are at the far end of human migration with limited intermixing over the medieval period, both due to isolation and hostility to/from outsiders; yet the variation in human appearance - face shape/type, hair colours, body shapes, etc. is just as pronounced as in the mixed-up, urban areas. I bet if we were familiar with it, other isolated areas/groups like the bushmen, New Guinea, and the farthest reaches of the polynesian migration would show equal variation. I suspect variations like jawline, nose shape, cheekbone shape, and body fat distribution, like hair colour, while roughly similar for some ethnic groups are genetic diversity indicators like eye colour. They don’t “mush together” over time, but the separate genes circulate in the population creating distinct faces and body types unless they all end up coming from one source - the real “bottleneck” situation. Red hair- for example - if it blended with other genes, there would not be so many distinctive reh-heads in celtic populations. OTOH, skin colour comes from a multiple set of genes, and does appear to blend as mixed generations get a rough proportion of both parents’ genes. However, even after 200-plus years, there are still very black and very white people in America and everything in between. If prejudice disappeared overnight, I suspect the diversity would be there for centuries and there would still be pockets of pure colours. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [December 3, 2011, 7:32pm UTC](https://boards.straightdope.com/t/human-speciation/604866/29 "2011-12-03T19:32:59Z")
> [@md2000](#): > > As for another part of the OP, some rural parts of areas like highland Scotland, Ireland, Iceland, lapland etc. are at the far end of human migration with limited intermixing over the medieval period, both due to isolation and hostility to/from outsiders; yet the variation in human appearance - face shape/type, hair colours, body shapes, etc. is just as pronounced as in the mixed-up, urban areas. I’ve never been to Lapland, but I’d be surprised to see anyone like [this](http://en.wikipedia.org/wiki/File:Tiger_Woods_drives_by_Allison.jpg)– a common site in most large cities in the Western world. ---
**Author:** ![Enola\_Gay](https://avatars.discourse-cdn.com/v4/letter/e/3ab097/32.png) [@Enola\_Gay](https://boards.straightdope.com/u/Enola_Gay)\ **Post date:** [December 3, 2011, 8:19pm UTC](https://boards.straightdope.com/t/human-speciation/604866/30 "2011-12-03T20:19:21Z")
> [@John\_Mace](#): > > I’ve never been to Lapland, but I’d be surprised to see anyone like [this](http://en.wikipedia.org/wiki/File:Tiger_Woods_drives_by_Allison.jpg)– a common site in most large cities in the Western world. I was in Helsinki once and attended a Laplander festival. I was surprised at the appearance of the people–they didn’t look Scandinavian at all, but rather looked like Asians with blue eyes and lighter hair. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [December 3, 2011, 8:23pm UTC](https://boards.straightdope.com/t/human-speciation/604866/31 "2011-12-03T20:23:08Z")
> [@Enola\_Gay](#): > > I was in Helsinki once and attended a Laplander festival. I was surprised at the appearance of the people–they didn’t look Scandinavian at all, but rather looked like Asians with blue eyes and lighter hair. They are an interesting people. From wikipedia: > [@](#): > > Anthropologists have been studying the Sami people for hundreds of years for their assumed physical and cultural differences from the rest of Europeans. Recent genetic studies have indicated that the two most frequent maternal lineages of the Sámi people are the haplogroups V and the U5b, ancient in Europe. By contrast, the most common paternal lineage among the Sami indicates an Asian origin, who may represent a Uralic-speaking people. ---
**Author:** ![Enola\_Gay](https://avatars.discourse-cdn.com/v4/letter/e/3ab097/32.png) [@Enola\_Gay](https://boards.straightdope.com/u/Enola_Gay)\ **Post date:** [December 3, 2011, 8:32pm UTC](https://boards.straightdope.com/t/human-speciation/604866/32 "2011-12-03T20:32:38Z")
> [@John\_Mace](#): > > They are an interesting people. From wikipedia: That’s fascinating. I didn’t know much about Laplanders before going to that festival, which we just happened upon, but I just assumed they would look like Finns or Swedes. From a distance, they looked like a group of Asian people (it was cold and they had hats on so hair color wasn’t immediately apparent), but when we got close up we saw that they all had bright blue eyes. Makes sense if they have some Asian genetics. ---
**Author:** ![Corresponder](https://avatars.discourse-cdn.com/v4/letter/c/22d042/32.png) [@Corresponder](https://boards.straightdope.com/u/Corresponder)\ **Post date:** [December 4, 2011, 5:10am UTC](https://boards.straightdope.com/t/human-speciation/604866/33 "2011-12-04T05:10:49Z")
Chimps have 48 chromosomes and humans 46, so they wouldn’t be able to interbreed and produce fertile offspring, or probably even “mules.” ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [December 4, 2011, 6:18am UTC](https://boards.straightdope.com/t/human-speciation/604866/34 "2011-12-04T06:18:10Z")
> [@Corresponder](#): > > Chimps have 48 chromosomes and humans 46, so they wouldn’t be able to interbreed and produce fertile offspring, or probably even “mules.” Not true. Usually true, but not always. Przewalski’s horses have one more chromosome pair than domestic horses, and hybrids are fertile. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [December 4, 2011, 9:03am UTC](https://boards.straightdope.com/t/human-speciation/604866/35 "2011-12-04T09:03:05Z")
I’ve read a claim that chimpanzees and early hominids did in fact interbreed during a 9 Million to 6 Million years ago time frame, though of course they were much closer genetically then. Here are [two](http://www.livescience.com/3996-humans-chimps-split.html) [cites](http://www.msnbc.msn.com/id/12836649/ns/technology_and_science-science/t/did-chimp-human-ancestors-interbreed) (though neither appears to be the longish article I read a few years ago ☹ ). On another matter: I’ve a question about the relative contributions of crossover and mutation to genetic diversity. I’d have assumed that crossover would usually be more important over a short period (few thousand years) especially when “irrelevant” mutations are ignored. If we assume that crossover is more important, the homogeneity of cheetahs is due strictly to the (roughly 10,000 years ago) bottleneck, estimated at six individuals or less, which leads to all cheetahs still being related much closer than 1st cousins. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [December 4, 2011, 9:28am UTC](https://boards.straightdope.com/t/human-speciation/604866/36 "2011-12-04T09:28:25Z")
BTW, on the matter of crossbreeding animals with different numbers of chromosome, I visited a farm in Thailand several months ago that breeds a hybrid of _Bubalus bubalis_ and _Bubalus murrensis_, both “water buffalo” but with 48 and 50 chromosomes respectively. The only factoid I remember about the hybridization is that chromosome mismatch occurs only during the first hybrid generation. The reason to introduce European genes to the Thai buffalo is, I think, to get better or more mozzarella cheese! (I just tagged along to the farm with a friend involved in experimental farming; **septimus** has his hands full raising two young specima of _H. sapiens_ 😉 ) ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [December 4, 2011, 2:44pm UTC](https://boards.straightdope.com/t/human-speciation/604866/37 "2011-12-04T14:44:47Z")
The importance of chromosome number in speciation is beginning to be vastly overstated in the lay mind, from what I’ve seen lately. I think it’s made it into the high school curriculum or something, because I’ve seen a lot of questions about it here and there. What matters is whether or not all of the chromosomes can successfully pair up during meiosis, not how many chunks the DNA is broken in to. For instance, it’s well known that our chromosome 2 is descended from two separate ape chromosomes, called 2A and 2B, IIRC. So in a hypothetical hybrid with one humans c’some 2 and two ape c’somes 2A and 2B, then the 2A could pair with one arm of the human 2, and the 2B could pair with the other arm. Meoisis would then occur with no problem. Now, obviously, chromosome rearrangements like that will eventually diverge over evolutionary time, until they reach a point where pairing is no longer possible, but the act of changing numbers itself is not terribly important. Otherwise, it would never be able to spread through a population and fix in the species. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [December 4, 2011, 2:51pm UTC](https://boards.straightdope.com/t/human-speciation/604866/38 "2011-12-04T14:51:19Z")
> [@septimus](#): > > I’ve read a claim that chimpanzees and early hominids did in fact interbreed during a 9 Million to 6 Million years ago time frame, though of course they were much closer genetically then. Here are [two](http://www.livescience.com/3996-humans-chimps-split.html) [cites](http://www.msnbc.msn.com/id/12836649/ns/technology_and_science-science/t/did-chimp-human-ancestors-interbreed) (though neither appears to be the longish article I read a few years ago ☹ ). Yes, the hypothesis is that there were two splits. One that occurred about 9M years ago, then the lines merged again (at least somewhat) 6M years ago before splitting for good. So, it’s not that there was 4M years of interbreeding, but that the lines split twice. **Smeghead** : That is exactly right. Our chromosome 2 is more or less identical to the sum of 2 chimp chromosomes. It’s not like we have this completely extra chromosome apart from any genetic material in the chimp’s genome. ---
**Author:** ![Becky2844](https://avatars.discourse-cdn.com/v4/letter/b/91b2a8/32.png) [@Becky2844](https://boards.straightdope.com/u/Becky2844)\ **Post date:** [December 5, 2011, 3:28am UTC](https://boards.straightdope.com/t/human-speciation/604866/39 "2011-12-05T03:28:49Z")
> [@Broomstick](#): > > It seems to make them highly resistant, if not entirely immune, to high altitude pulmonary and cerebral edema. Also less likely to have blood clots at extremely high altitudes, such as on Everest. Tibetan women are able to carry babies to full term at higher altitudes than non-Tibetans, and even at moderately high altitudes their babies tend to have a slightly heavier birthrate and fewer problems breathing thin air. > > Of course, get them high enough (like on Everest) they still have problems. They can still show signs of altitude sickness. It’s just that their “death zone” starts a little higher up the mountains than it does for the rest of us. I’m going to step back a minute and pat myself on the back for understanding some of what’s being said here. I swear, some of you all are so smart that I…I just…LOVE IT. BTW I’m thrilled to have taken Anthropology taught by Dr. Bill Bass at UT. I barely passed but enjoyed every minute. ---
**Author:** ![robert\_columbia](https://avatars.discourse-cdn.com/v4/letter/r/e79b87/32.png) [@robert\_columbia](https://boards.straightdope.com/u/robert_columbia)\ **Post date:** [December 5, 2011, 4:14am UTC](https://boards.straightdope.com/t/human-speciation/604866/40 "2011-12-05T04:14:49Z")
> [@Broomstick](#): > > It seems to make them highly resistant, if not entirely immune, to high altitude pulmonary and cerebral edema. Also less likely to have blood clots at extremely high altitudes, such as on Everest. Tibetan women are able to carry babies to full term at higher altitudes than non-Tibetans, and even at moderately high altitudes their babies tend to have a slightly heavier birthrate and fewer problems breathing thin air. > > Of course, get them high enough (like on Everest) they still have problems. They can still show signs of altitude sickness. It’s just that their “death zone” starts a little higher up the mountains than it does for the rest of us. And, I thought it was well-known that white Europeans were adapted better to survival at higher latitudes because they produce more Vitamin D per unit of sunlight than black sub-Saharan Africans (but not to say that blacks automatically drop dead at higher latitudes, they don’t, they just may not be as healthy) , and on the other hand, the sub-Saharan Africans have a greater resistance to sunburn than Europeans, meaning that they can be out in the UV for a longer period of time and suffer less health degradation than a European out in that same sunlight. [Previous page](https://boards.straightdope.com/t/human-speciation/604866.md?page=1) [Next page](https://boards.straightdope.com/t/human-speciation/604866.md?page=3)