Human evolutionary genetics is too sexy...

Say you have a abstruse paper such as, Accelerated genetic drift on chromosome X during the human dispersal out of Africa:

Comparisons of chromosome X and the autosomes can illuminate differences in the histories of males and females as well as shed light on the forces of natural selection. We compared the patterns of variation in these parts of the genome using two datasets that we assembled for this study that are both genomic in scale. Three independent analyses show that around the time of the dispersal of modern humans out of Africa, chromosome X experienced much more genetic drift than is expected from the pattern on the autosomes. This is not predicted by known episodes of demographic history, and we found no similar patterns associated with the dispersals into East Asia and Europe. We conclude that a sex-biased process that reduced the female effective population size, or an episode of natural selection unusually affecting chromosome X, was associated with the founding of non-African populations.

Over at Gene Expression Classic p-ter expresses his befuddlement:

At the same time, another group (Keinan et al.) was independently looking at this issue in other datasets. Their analysis, published today is markedly different. In particular, they see the exact opposite of the pattern in Hammer et al.--a decrease in the X/autosome ratio in effective population size compared to 0.75 (a figure from their paper is on the right. Note that the y-axis is the same in both this and the Hammer et al. figure--the x/autosome ratio in Ne. In both, the solid horizontal line is at 0.75). . And this is not due to extremely different methodologies--one of the analyses presented by Keinan et al. is very similar to that in Hammer et al., only using different data.

So this is all a bit odd, to say the least.

All right. So how does this play in the press? They go crazy! Did warfare drive out-of-Africa migration?:

Roving bands of men might have waged history's first traceable war against the ancestors of all Europeans, Asians and other non-Africans, some 60,000 years ago.

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Highly Punctuated Patterns of Population Structure on the X Chromosome and Implications for African Evolutionary History: It is well known that average levels of population structure are higher on the X chromosome compared to autosomes in humans. However, there have been surprisingly few analyses…
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A few days ago I discussed a new paper which explores the patterns of natural selection in the genome of the X chromosome. As you know the X is "carried" disproportionately by females, as males have only one copy, so it offers up an interesting window into evolutionary dynamics (see The Red Queen…
Sometimes I wonder if the period between the publication of The History and Geography of Human Genes and The Journey of Man, roughly from the mid-90s to the early 2000s, will be seen as a golden age for historical population genetics in hindsight. A few weeks ago I pointed to new data based on DNA…

A person centric model of gene migration would suggest small traveling bands with only a few women surviving.

A gene centric model gives a different picture. Consider humanity as being spread continuously along a migration path. Genes are transported along that path as men and women move between between tribes. The female gene carriers remain close to home while the male carriers range much farther. The effective population size for the male carried genes would be greater than the effective population of the female carried genes.

When I was a kid learning Bible stories, I wondered where all the other people came from. First there are only A&E then suddenly there was Cain being exiled into the land of Nod. Where did the Nodians come from.

So with this story. Our ancestors, mostly men came out of Africa. So who were the Nodians that they made tender sweet love with? Were they mating ladies of less advanced groups? wouldn't they then have produced hybrids? Where are the genes of these lesser ladies. Etc??

By plschwartz (not verified) on 23 Dec 2008 #permalink