>> Glenn cites the following quote as proof that the ZFY location monomorphism
>> is not valid in estimating the age of the human or chimp common
>> ancestor:
> "These results are not inconsistent with a recent sequencing survey of
>the third intron of the Zfy gene that revealed complete monomorphism. when
>the HKA test is applied (in comparisons with both mtDNA and [beta]-globin),
>the null hypothesis is not rejected. However, the unusually low level of
>divergence between human and chimpanzee Zfy introns (a nearly threefold lower
>D value compared with the YAP locus) makes this region uninformative for
>inferring human population history."~Michael F. Hammer, "A Recent Common
>Ancestry for Human Y Chromosomes," Nature, 378, Nov. 23, 1995, p. 377.
>> What Hammer is saying here is that ZFY introns are invalid for inferring
>> human population history BECAUSE THEY DON'T AGREE WITH THE CONVENTIONAL
>> EVOLUTIONARY HYPOTHESIS. THIS IS CIRCULAR REASONING.
Hammer said nothing of the sort; this is your inference only.
I took it to mean that this gene has changed very slowly (presumeably
because it is tightly constrained by natural selection). Because of
this slow rate of modification, all humans share the same form of that
gene, which means that it can't tell us anything about the relationships
between different human populations. Why does that conflict with
evolutionary theory?
-- Jim Foley Symbios Logic, Fort Collins, COJim.Foley@symbios.com (303) 223-5100 x9765 I've got a plan so cunning you could put a tail on it and call it a weasel. -- Edmund Blackadder