Re: Clarification on relationship between Morphology and genes
Jane Andrews (mja1002@cus.cam.ac.uk)
Thu, 18 Jul 1996 18:04:22 +0100
I think that the discussion of this topic may be confusing two seperate
phenomena, the first being genetic difference between chimps and humans and
the second the genetic variation between modern human populations or
"races" if you choose to call them that.
The genetic distance between modern humans and chimpazees as determined
by DNA-DNA hybridisation is often quoted as around 2%. For example,
Sibley and Alquist (J. Mol. Evol.1984 20:2-15) give a figure of
1.6% difference.
Questions about the 10 or 6% difference between "races" refer to the
amount of variation within the modern human species. A variety of
genetic markers, including blood groups, have shown the degree of
variation within populations to be much higher than that between
populations. Figures widly suggested are of 90% and 10% respectively.
In other words, on average, only 10% of the total variation between any 2
individuals will be the effect of population/ethinic group/race or
whatever you want to call it. The remaining 90% (on average) will be due
to other factors. This does not mean that there is a 10% genetic
difference between modern populations, but that 10 of the variation
arises from population afinities. Interestingly, the figures for
craniometric variation are very similar to those from genetic markers.
The only reference I can give off hand refers to this, but it contains
plenty of references for the genetic work if you are interested.
Relethford 1994 AJPA 95:53-62.
Jane Andrews.
Hominid Evolutionary Biology Research Group.
Cambridge University.
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