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The Great Human Diasporas

Posted by: Floyd ( Darwin Fan Club, People's Republic of West 40th Street ) on August 27, 1999 at 11:03:23:

In Reply to: Good point posted by Nikhil Jaikumar on August 22, 1999 at 23:19:12:

: In fact, sources I've seen state that humans, as a species, are far LESS diverse than many animals like chimpanzees fopr example. A West African and an Australian have much more genetic similarity then a Nigerian chimp anfd a Gabonese chimp, for example.

Yes! Actually the genus Pan contains two species, P. paniscus (the Bonobo, or "Pigmy chimp,") and (the "common" chimp). (In fact, Jared Diamond has argued that a 3rd species of Pan called P. sapiens would also be recognized, if members of this species weren't the ones making the classifications!)

:this is apparently attributed to a large cataclysm at some point in teh unknown past which wiped out most of the human race, creating a bottleneck effect of wiping out most genetic variation.

Actually the "bottleneck" wasn't so much a cataclysm (at least nothing that would have been recognized as such at the time) as it was simple isolation of a breeding pool and consequent divergence. The two recognized genera of Pan probably diverged less than a few million years ago, and I would bet that it can be explained by Pleistocene dessication of west Africa, and consequent discontinuities in the distribution of the tropical rainforest band. The chimp/human split was only 5 to 7 mya, and was probably equally as non-catastrophic. The work by the Wilson group at Berkely suggests that all living people are descended from a small, geographically isolated band of no more than 1000 actively interbreeding females (because mtDNA is only passed maternally). This date, and the location suggested by the variation evidence, identifies the ancestors of all living people as a small group of Homo erectus (subspecies ergaster) in central Africa in the later Pleistocene.

: Dr. Cavalli-Sforza of Stanford did a relaly interesting study on that subject. apparently Africans and Australian aborigines, in spite of their similar dark skin color, are the two most genetically different of any group, while Africans and whites are the most similar. Shows how much skin color means. Really, if yu used lactose intolerance as your defining criterion, for "race", then suddenly you would only have two races of humans. The Swedes and the Fulani of west Africa would be in one, while Pygmies and Italians would be in the other. If you used blood protein as your crietrion, you'd have another set again...and so on.

(Cavalli-Sforza is one of my personal heroes, thanks for mentioning him. BTW, if you haven't yet read The Great Human Diasporas, do so. There's some great info on the "Pigmys" for your ongoing debate on that subject.)
You're absolutely right! The historical reason why skin color was used as a racial identifier is that it is immediately visible, whereas lactose tolerance, blood type, language, religion, political party, astrological sign, and all the other (usually foolish) ways people use to divide themselves from each other are not so easy to see.

: Interestingly, until recently in Brazil economic status helped define your race. If you were a wealthy black man you were reclassified as white, and vise versa. Similarly, in traditional Rwanda, a Hutu man who acquired many cattle and high status was reclassified as a Tutsi.

And of course there's the fact that Hutus and Tutsis consider themselves different "races," while here in the U.S., the "cousins" of contemporary west Africans are all considered (and for the most part all consider themselves) to be of the same "racial" group. This is because "racial" categories are culturally defined, like most classification systems, and the criteria for membership in one class or another is a culturally (and therefore historically) contingent phenomenon.

Now, to follow a trend begun by my very respected colleague, Lark, "on an entirely different point altogether," are you (or any of our other confrerees) going to be visiting Seattle for the WTO meetings?
-Floyd



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