Posted: Sat 21 Apr 2007 02:55 Post subject: There are three races of chimps
According to a University of Chicago study, common chimpanzees (P. troglodytes), come in three distinct races or subspecies. This is in contrast to human beings (H. sapiens), who have only one race. The three races of chimps are in addition to the bonobos (P. paniscus), who are a separate species entirely. Bonobos split off from chimps about 800 kya, roughly when H. heidelbergensis split from H. ergaster. The Western race of chimps then split off about 500 kya, about the same time that H. sapiens and H. neanderthalensis divided. And the Eastern and Central races of chimps then divided about 250 kya. It makes you wonder whether at one time there may have existed separate races of H. sapiens and whether we, the only surviving race, are merely the sole survivors of some prehistoric cataclysm.
Joined: 20 Oct 2006 {Posts: 283 } Location: Akron, Ohio
Posted: Sat 21 Apr 2007 06:59 Post subject:
Frank said:
''It makes you wonder whether at one time there may have existed separate races of H. sapiens and whether we, the only surviving race, are merely the sole survivors of some prehistoric cataclysm.''
If this be the case then those that survived evidently had a very strong pre-cataclysm genetic connection to perpetuate the species. How else to explain phenotype. It came from somewhere. I have no problem with the idea at all.
Roughly six billion people are on this planet and a number of them are recognizably different so as to give meaningful thought to it.
That is one possibility: that the survivors of a speculated cataclysm retained a large enough gene pool so that pre-cataclysm phenotypes were preserved in their genes. The other, more widely suggested, alternative is that all the variation that we now see resulted from post-cataclysm adaptations and family differences as we fanned out across the globe.
One problem in hypothesizing about sub-speciation in H. sapiens compared to P. troglodytes, is that the latter hates water. Chimps can swim but avoid it. And so, even modest rivers create genetic isolation between chimp populations, which leads to genetic divergence, then races, and finally species. But humans go anywhere and interbreed with locals wherever they go, so the collective gene pool is always being stirred and mixed. Genetic isolation is impossible. Hence, no real underlying divergence (beyond superficial phenotype differences) can arise, and so no races can appear.
As I recall, some time ago some of us (George? William?) discussed a scenario where extraterrestrial alien zoologists took two breeding populations of H. sapiens from Earth and kept them in different zoos in different solar systems. How many ky of such genetic isolation would suffice to produce two races; how long would it take to produce two species (no longer interfertile)?
Joined: 20 Oct 2006 {Posts: 283 } Location: Akron, Ohio
Posted: Sun 22 Apr 2007 01:31 Post subject:
Frank said:
''The other, more widely suggested, alternative is that all the variation that we now see resulted from post-cataclysm adaptations and family differences as we fanned out across the globe.''
If the speculative cataclysm destroyed the population then where would the new genetic information come from so that a post-cataclysm colony could thrive? So someone, male and female, had to make it through I think.
''As I recall, some time ago some of us (George? William?) discussed a scenario where extraterrestrial alien zoologists took two breeding populations of H. sapiens from Earth and kept them in different zoos in different solar systems. How many ky of such genetic isolation would suffice to produce two races; how long would it take to produce two species (no longer interfertile)''
Well if there is any group of extraterrestrials out there that can pull this feat off then I would say they may well not have a need to go to those distant solar systems to make their ''zoo'' work. One would think they would be sufficiently aware of the genome to do it right here.
On the other hand I guess it might be asking a Cessna 172 pilot (rocket engine/different solar systems) who is only trained in visual flying rules (VFR) to fly a 747 and use its instruments (speed of light). Advanced but not sufficiently so.
If the speculative cataclysm destroyed the population then where would the new genetic information come from so that a post-cataclysm colony could thrive? So someone, male and female, had to make it through I think.
Of course. How this got started is that there is a strange pattern of diversity in our genome that can be interpreted as evidence of a bottleneck event. If you interpret the pattern as evidence of a bottleneck event (a big if!), then the best guesstimates of how many people made it through the event range from 2,000 to 10,000 individuals.
Andrew Waters wrote:
Well if there is any group of extraterrestrials out there that can pull this feat off then I would say they may well not have a need to go to those distant solar systems to make their ''zoo'' work. One would think they would be sufficiently aware of the genome to do it right here.
No one was actually positing ETs. It was simply a way of imagining a situation where two populations of humans could be isolated from each other (an impossibility in real life as long we can go anywhere). The feeling was that it would take several hundred ky to produce separate races and perhaps 2 million years to produce two species that could no longer interbreed. Again, there was no particular point to it, it was just a thought experiment.
Joined: 04 May 2005 {Posts: 2021 } Location: santiago, chile
Posted: Sun 22 Apr 2007 15:27 Post subject: Subspecies
The concept of "race" or "subspecie" is a complex one, I believe.
That chimps have three subspecies is no wonder: they are a wild specie of animal.
Human beings, on the other side, are DOMESTIC animals.
In the wild, species like lions, elephants, jirafes, etc., do have subspecies with quite marked limits between them.
On the other hand, the varieties in human beings follow similar patterns to the variations in cats, dogs, cows, horses, etc. In domestic species variation can be quite amazing. Think in the difference in size between a Swiss Saint Bernard dog and a Chihuahua, or between a Holland and a Indian cow. However, there is a continuity between the extremes. They form a single species without radical boundaries.
The same happens in humans, I believe. Variations exists but they are not sharply enough to divided humans in subspecies, and clinal distribution between those variations is the norm.
Ironically, C Loring Brace is using this information to further his belief that Humans are descended from Neanderthals (All humans according to him). He says the genetic difference between Neanderthals and humans are lass than the genetic difference between different populations of chimpanzees.
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