human/chimp identity

Brian Foley btf at lanl.gov
Mon Dec 6 18:51:31 EST 1999


Laurence Martin Cook wrote:
> 
> A short while ago Brian Foley wrote that sequence data show the human
> genome to be very invariant, while chimpanzees are variable.  It must
> depend where you look.

	The data I posted on were from over 10,000 bp of noncoding
region of the X chromosome, published in:

Kaessmann H, et al. 
    DNA sequence variation in a non-coding region of low 
	recombination on the human X chromosome. 
    Nat Genet. 1999 May;22(1):78-81. 

Kaessmann H, et al.
    Extensive nuclear DNA sequence diversity among chimpanzees. 
    Science. 1999 Nov 5;286(5442):1159-62. 

	The human genomes were not invariant, they just had
lower variability than the chimpanzees.  This is not that
surprising, given that we classify chimpanzees into 2
species (Pan troglodytes and Pan paniscus) with the former
having several subspecies (Pan troglodytes troglodytes,
pan troglodytes schweinfurthii, Pan troglodytes verus,
Pan troglodytes vellerosus), while we don't classify modern
humans into subspecies.

> Some years ago Eviatar nevo and collegues made a number of surveys of
> data from electrophoretically detectable protein studies of
> organisms.  In the one I am looking at, there is for man a
> probability of 0.47 that a locus is polymorphic (for 107 loci in 7349
> individuals).  Silent mutations will make this even higher at the
> DNA level, and it is not just systems like MHC which are involved
> The equivalent figures for Pan are P=0.079 (42 loci in 182
> individuals).  In the latter case only two populations were
> studied and it is possible variation between groups is great.
> 
>  "If you've seen one human, you've seen them all."  Not on this
> evidence, you haven't.  At the present time it seems necessary and
> interesting to review critically the evidence for variability coming
> from different types of investigation.  Has this been done?

	Yes.  I'd say both the method of detecting variablility
(nuclear autosome DNA, nuclear X or Y chromosome DNA, mitochondrial
DNA, protein electrophoresis, etc) and the sampling of the
species (it sounds like Eviatar Nevo and collegues may not
have randomly sampled many Pan groups) need to be considered.

> 
> Laurence M. Cook
> The Manchester Museum
> University of Manchester
> Manchester M13 9PL U.K.
> and:_lcook2 at excite.com
> 
> ---

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|Brian T. Foley               btf at t10.lanl.gov                 |
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