Y Chromosome Adam is a parallel to Mitochondrial Eve. Just as mitochondria are inherited solely from mothers, the Y chromosome is inherited solely from fathers. The difference is that only males get the Y chromosomes, but both males and females get mitochondria.

Interestingly, studies have been done on this subject. In Absence of Polymorphism at the ZFY Locus on the Human Y Chromosome, as indicated by its title, it was found that 38 males from all over the world had very little, or no* variance in a portion of the Y chromosome. The conclusion was that humanity has a common, single, ancestor absolutely no earlier than 270 000 years ago, otherwise we would have variance. Here are some possible interpretations of this study (not all of them, by any means):

  • "Adam"'s Y chromosome spread throughout and dominated an existing human population. This would happen if the quantity of males who were not male-descendants of "Adam" decreased to nothing.
  • Sometime between 270 000 BC and now there was a major (enough emphasis?) population crash, and only one male's family survived. Keeping with the theme, we could also call this guy "Y Chromosome Noah". :-)
  • The calculation method's logic is flawed, although I am uncertain on what grounds.
  • Humans were created, not evolved. I said possible interpretations, so don't downvote me for being encompassing.
Or some combination of these interpretations would work as well.

Another study done similarly has placed Y Chromosome Adam at maximum 188 000 years ago, and yet another at a recent 49 000.

* This is uncertainty on my part. I am only reporting the studies second hand. The information comes from the following URL (about half way down): http://www.reasons.org/resources/apologetics/humanevolution.html You may want to read the shorter http://reasons.org/resources/apologetics/chromosome.html.

There's obviously an interesting underlying concept here, and I don't want to knock anyone's religion or belief system, let alone xriso's, but there seems to be a horrible flaw in the studies mentioned and the conclusions drawn from those studies.

The argument presented in the document xriso kindly referred me to and from whence he drew his information (http://www.reasons.org/resources/apologetics/humanevolution.html) uses the lack of polymorphisms in the Y chromosome, and especially in the ZFY locus, to argue the relatively recent emergence of the latest human ancestor. The resources these studies are drawn from include papers from Science, Nature, and Genome Research, which are all well-renowned scientific journals. The reasons.org commentary even mentions the australpithecenes, Cro-Magnon man, and the Neandertals and their relative closeness to Homo sapiens sapiens. But what the published studies, and consequently the reasons.org commentary, seem to be lacking is any comparison between the Y chromosomes in Homo sapiens and the Y chromosomes in Australopithecus africanus, Homo habilis (an earlier species), or Homo neandertalensis (Neandertals) to see if there is more interspecies variation or if, in fact, the lack of variation is due to necessity. (It is known that in some genes, even a single base pair substitution can be lethal.)

It seems to me that such explosive and, indeed, incendiary conclusions should have been better researched in order to make a more definite approximation of the dawn of Homo sapiens-kind. It seems obvious simply from the fact that no one can even decide on a range of, say, 20,000 years that the first of Homo sapiens sapiens came about, then we shouldn't be drawing conclusions about the likelihood of one male spawning an entire species.

** I'd like to state for the record that this writeup is not intended to rebut everything that xriso said. It is merely intended to warn against the jumping to unjustified (IMO) conclusions that happened in the reasons.org source mentioned. Just so you all know.

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