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[–] seeker 1 points 9 points (+10|-1) ago  (edited ago)

No, the X/A ratio they calculated is not the similarity between the group and bonobos, otherwise the bonobo's value would be 1.0. I dont fully understand it bit it seems to be an in-group ratio of genetic diversity:

To approach this question in the Pan ancestor, we compared the inferred ancestral population sizes of the X chromosome and the autosomes. Because two-thirds of X chromosomes are found in females whereas autosomes are split equally between the two sexes, a ratio between their effective population sizes (X/A ratio) of 0.75 is expected under random mating.

It could be saying the mating history of africans is much closer to bonobos...

[–] chirogonemd 0 points 3 points (+3|-0) ago  (edited ago)

Autosomes (A) are non-sex chromosomes. The X/A ratio was developed to predict sex in drosophila (fruit fly). In the simplest terms, the X/A ratio is a measure of the x-content (female linked content) as a proportion of the autosomal genome.

Every generation is expected to have a ratio of .75, which is why there is a dashed line on the chart at that value. This is because each parental generation involves XX (mother) + XY (father). So, 3/4.

Deviation from this at the population level has to do with the varied mating success of females versus males in the group. The ratio increases when women are less protected and more promiscuous, and it decreases when men protect their women but fuck around more themselves.

So you could take away a couple things from this data: that African groups are more similar in mating habits to the Bonobo than Europeans are. Bonobos are more promiscuous in general but the females in particular are loose because male bonobos are quite subordinate, whereas with chimpanzees the males are dominant.

Another thing that could be taken from this is that over time, many men were taken OUT of the African population and into other populations, and that there was more inter-race mixing happening in Europe (of the foreign male with native female variety) leading to a lower X/A ratio. This would also lead to a lower proportion of successful males in Africa versus females, so the African X/A ratio would increase proportionally.

In other words, Europeans are more genetically diverse. European males tended to protect their females to a greater extent and are less subordinate (taken as: men prevented women from being as promiscuous as they were), but there was also a propensity for European women to mate with non-European males by CHOICE. You can't prove any of this based on the data, but the data could be used to make these hypothesis and support more research. It'll be a cold day in hell before most modern researchers take this much further along these lines, however. Remember, we're all the same! /s

[–] seeker 0 points 1 points (+1|-0) ago 

Thanks a lot for this clarification.

[–] Cooking_with_Alf 2 points 3 points (+5|-2) ago 

"Ancient alien theorists believe that the 'Gods' genetically modified Negroes with a combination of bonobo DNA and DNA extracted from neanderthal feces."

[–] Cat-hax 0 points 1 points (+1|-0) ago 

Fuck it, I wouldn't doubt it.