arab thoroughbreds

greg cochran says (or writes, i guess — unless he talks to his computer monitor like some of us people do…):

“If a new environment favored lower (or higher) aggressiveness in males, a Y-chromosome that induced lower (or higher) aggressiveness would take off. And since different Y chromosomes do indeed affect the level of aggressiveness in mice [which I just found out], possibly by affecting testosterone production – this mechanism is plausible….

“Fortunately for all concerned, the selective value of aggressiveness, etc. has been the same for all human populations forever and ever, before and after the development of agriculture. Otherwise you might see weirdly rapid expansions of particular Y-chromosome haplogroups – common, yet only a few thousand years old.”

i nominate as one such example of this selection that never happened the “YCAII=22-22 and DYS388≥15” cluster of haplogroup J-M267 which, depending on who you read, may or may not be related to the arabs’ expansion out of their peninsula in historic times. whatever the full story, haplogroup J-M267 certainly looks arab-expansiony:

HG_J1_(ADN-Y)

hage and marck have shown how mating patterns can affect the distribution of sex chromosome haplogroups (mmmm-hmmm!). the prevalence of father’s brother’s daughter’s (fbd) marriage amongst the arabs could certainly have had an effect on the successful distribution of the J-M267 haplogroup, especially the YCAII-whatchamacallit cluster mentioned above if it was really connected to the arab expansion.

remember that fbd marriage concentrates y-chromosome types into these patrilineages, so fathers, sons, grandfathers, paternal uncles, paternal nephews, paternal male cousins, etc., all share the same y-chromosome (barring variations due to mutations, of course):

parallel cousin marriage

of particular interest is how men (“C” in diagram above) ensure that their male grandchildren by their daughters (“E” in diagram above) also have their y-chromosome, ’cause they marry their daughters off to their paternal nephews (i talked about that here). this doesn’t happen in most marriage systems. so, really, ALL the males in (ideal) arab, fbd patrilineages share the same y-chromosome.

this is one way that inbreeding could serve to accelerate the acquisition of “genes for altruism” in a population. if, say, those genes were aggression genes on the y-chromosome — genes that led to altruistic behaviors in the sense that the individuals having them were more likely to “kill thy unrelated neighbor” and make life better for themselves and their own — then inbreeding, especially father’s brother’s daughter’s marriage, could help those genes pile up more quickly.

(note: comments do not require an email. arab thoroughbred.)

22 Comments

  1. Difficult to see how any competition for a hot cousin, tending to be between men with the same Y chromosome, would aid the spead of Y chromosomes for altruism.

    I wonder about a how a Y-chromosome conferring aggressiveness could flourish in a society with many marriages betweens cousins; wouldn’t those circumstances entail arranged marriage whereby the man does not have to be aggressive (nor extrovert, charming or attractive) at all. Descendants of the Prophet are a more likely bet for a successful Arab male line.

    Polygyny is the marriage system whereby there are unsuccessful y-chromosomes excluded from reproduction. Where there is the most polygyny is where you will find the most intense selection for being aggressive extrovert and charming. Cochran doesn’t accept that consanguineous marriage is common where there is polygyny.

    Reply

  2. @hbd chick: You never cease to amaze. That is a very astute suggestion. I am not hoping you are right on this one.
    I don’t know whether this helps, but the map showing the distribution of the gene reminds me kind-of, sort-of, maybe of the map of the distribution of Rh negative alleles, up Egypt, across North Africa and up west coast Europe with a fair glop in the general area of the Kurds near the Caspian.
    Of course the blood type distrubtion goes back a long time before the Arab expansion. The whole thing may be just my fevered imagination or maybe the route is an easy one to expand along, which would not detract from your point either.

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  3. @sean – “Difficult to see how any competition for a hot cousin, tending to be between men with the same Y chromosome, would aid the spead of Y chromosomes for altruism.”

    that’s not what i said. that’s not the argument. that’s not the point.

    once again (and again), you are failing to READ (and comprehend) before commenting.

    Reply

  4. Sean
    “Difficult to see how any competition for a hot cousin, tending to be between men with the same Y chromosome, would aid the spead of Y chromosomes for altruism.”

    There’s no competition. The marriages are arranged.

    Reply

  5. This is a very interesting post. J-M267 certainly could be indicative of an Arab expansion in terms of its geographical spread. However with a possible origin anywhere between 4kya – 34kya, I expect it could have spread in many different waves at many different times. We know that the Sahara was habitable from 10.5kya – 5.5kya and was populated by pastoralist communities (as attested to by rock art, etc.). Then rapid dessication set in, causing populations to retreat, probably northwards to the Mediterranean coast, westwards to the Atlantic coast, and eastwards to the Nile valley. This could certainly account to some degree for J-M267 distribution in Africa.

    In regards to consanguinous marriage, I suspect this was common in West Asia long prior to Arab expansions but I have no proof. Incidentally, on the subject of testosterone and genetics (related to aggression in populations?), I have found a paper which outlines a link between frequencies of particular Human Leukocyte Antigen (HLA) alleles in male human populations, and serum testosterone concentrations. The information can be found on Table 2 (scroll down for it).

    http://rheumatology.oxfordjournals.org/content/39/7/758.full.pdf

    For Class I HLA alleles, the HLA-B the allele associated with the highest mean serum Te concentration (9.7 ng/ml) was B5. B5 is split into B51 and B52.

    Frequencies of B51 alleles in world populations can be found here:-

    http://www.allelefrequencies.net/hla6006a.asp?hla_locus_type=Classical&hla_locus=B&hla_allele1=B*51%3A01&hla_allele2=B*51%3A01&hla_selection=&hla_pop_selection=&hla_population=&hla_country=&hla_dataset=&hla_region=&hla_ethnic=&hla_study=&hla_order=order_2&hla_sample_size_pattern=equal&hla_sample_size=&hla_sample_year_pattern=equal&hla_sample_year=&hla_level_pattern=equal&hla_level=&hla_show=

    Frequencies of B52 in world populations:-

    http://www.allelefrequencies.net/hla6006a.asp?hla_locus_type=Classical&hla_locus=B&hla_allele1=B*52&hla_allele2=B*52&hla_selection=&hla_pop_selection=&hla_population=&hla_country=&hla_dataset=&hla_region=&hla_ethnic=&hla_study=&hla_order=order_2&hla_sample_size_pattern=equal&hla_sample_size=&hla_sample_year_pattern=equal&hla_sample_year=&hla_level_pattern=equal&hla_level=&hla_show=

    For HLA-A, A3 had the highest mean serum Te concentration (9.4 ng/ml). Frequencies of A3 in world populations:-

    http://www.allelefrequencies.net/hla6006a.asp?hla_locus_type=Classical&hla_locus=A&hla_allele1=A*03&hla_allele2=A*03&hla_selection=&hla_pop_selection=&hla_population=&hla_country=&hla_dataset=&hla_region=&hla_ethnic=&hla_study=&hla_order=order_2&hla_sample_size_pattern=equal&hla_sample_size=&hla_sample_year_pattern=equal&hla_sample_year=&hla_level_pattern=equal&hla_level=&hla_show=

    Chris.

    Reply

  6. @chrisdavies09 – “This is a very interesting post. J-M267 certainly could be indicative of an Arab expansion in terms of its geographical spread. However with a possible origin anywhere between 4kya – 34kya, I expect it could have spread in many different waves at many different times.”

    absolutely. however, the interesting verson of J-M267 wrt the arab expansion is that “YCAII=22-22 and DYS388≥15″ cluster. that appears to be a lot younger, possibly coinciding with the arab expansion. or maybe not, depending on which geneticist you read (see the two links in the post above — there are also more articles out there on this cluster, several of which are referenced on the J-M267 wikipedia page).

    @chrisdavies09 – “In regards to consanguinous marriage, I suspect this was common in West Asia long prior to Arab expansions but I have no proof.”

    sure. i agree. again, though, the specific form of consanguineous marriage amongst the arabs that i wanted to draw attention to in this post is fbd marriage. with that form, you get this hyper-focusing of y-chromosomes in patrilineages. with other forms of cousin marriage (or non-consanguineous marriage), not so much.

    teh anthropologists think that fbd marriage got started in the levant and was brought to the arabs via jewish tribes migrating southwards. i think greying wanderer at some point suggested that maybe fbd marriage got started down in yemen (didn’t you say that, g.w.?). i kinda like that idea … and it would match with the arab expansion. but i have no proof of this, so it’s just wild speculation.

    @chrisdavies09 – ” Incidentally, on the subject of testosterone and genetics (related to aggression in populations?), I have found a paper which outlines a link between frequencies of particular Human Leukocyte Antigen (HLA) alleles in male human populations, and serum testosterone concentrations.”

    thanks! (^_^)

    Reply

  7. hubchik
    “i think greying wanderer at some point suggested that maybe fbd marriage got started down in yemen (didn’t you say that, g.w.?). i kinda like that idea … and it would match with the arab expansion. but i have no proof of this, so it’s just wild speculation.”

    Yes, i can’t remember why though :)

    Reply

  8. “anthropologists think that fbd marriage got started in the levant and was brought to the arabs via jewish tribes migrating southwards.”

    Is it in the Bible? I should know but I don’t.

    Reply

  9. Cochran is talking about the aggression level conferred by a particular Y chromosome variant causing it to spead. I understand that. It seems to me the word altruism is being used in a different sense to the commonly accepted meaning when it signifies merely not being aggressive. To me altruism is actually helping someone else at some cost to oneself I think in a fbd marriage system the man with a Y chomosome for being actually altruistic to relatives, is going to to be at a disadvantage to relatives who don’t have the same Y chromosome.

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  10. So, in my opinion gene culture coevolution under a fbm system is going to be for the spread of Y chomosomes that do not make men altruistic toward relatives . Altruism genes could spread by FBM, but not on the Y chomosome.

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  11. “ALL the males in (ideal) arab, fbd patrilineages share the same y-chromosome.
    this is one way that inbreeding could serve to accelerate the acquisition of “genes for altruism” in a population. if, say, those genes were aggression genes on the y-chromosome — genes that led to altruistic behaviors in the sense that the individuals having them were more likely to “kill thy unrelated neighbor” ”

    In theory I’m sure that’s plausible, but it it seems to me – just an intuition – that genes for both altruism and aggression on the Y chromosome would not create much of a pressure for FBD marriage, while Y chromosomes with just high levels of general aggression actually have (going by how violent areas with FBD marriage are).

    Reply

  12. @szopeno – “Woots! Kanazawa was banned again – this time from bigthink. And the rationale given was that he was sexist and racist 8-O”

    oh, geez. *roll eyes* thanks for letting me know!

    it’s good to see a lot of people sticking up for kanazawa/politically incorrect thought in the comments @big think! (^_^) there’s hope for humanity yet … maybe ….

    Reply

  13. @luke – “Interesting hypothesis. Is it testable?”

    which hypothesis? (not that there really was an actual, scientific hypothesis in anything i said up there…. (~_^) )

    Reply

  14. @luke – “Is it in the Bible? I should know but I don’t.”

    there are a bunch of marriage regulations in leviticus — none of them ban cousin marriage.

    numbers 36:1-10 prescribes marriage within the patrilineage (so fdb marriage could be included there) so as to avoid giving away the family wealth/inheritance to outsiders (i.e. don’t give away the land of judea to un-chosen peoples!):

    “The heads of the fathers’ houses of the families of the sons of Gilead the son of Machir, son of Manas′seh, of the fathers’ houses of the sons of Joseph, came near and spoke before Moses and before the leaders, the heads of the fathers’ houses of the people of Israel; they said, ‘The Lord commanded my lord to give the land for inheritance by lot to the people of Israel; and my lord was commanded by the Lord to give the inheritance of Zelo′phehad our brother to his daughters. But if they [i.e. the daughters] are married to any of the sons of the other tribes of the people of Israel then their inheritance will be taken from the inheritance of our fathers, and added to the inheritance of the tribe to which they belong; so it will be taken away from the lot of our inheritance. And when the jubilee of the people of Israel comes, then their inheritance will be added to the inheritance of the tribe to which they belong; and their inheritance will be taken from the inheritance of the tribe of our fathers.’

    “And Moses commanded the people of Israel according to the word of the Lord, saying, ‘The tribe of the sons of Joseph is right. This is what the Lord commands concerning the daughters of Zelo′phehad, “Let them marry whom they think best; only, they shall marry within the family of the tribe of their father. The inheritance of the people of Israel shall not be transferred from one tribe to another; for every one of the people of Israel shall cleave to the inheritance of the tribe of his fathers And every daughter who possesses an inheritance in any tribe of the people of Israel shall be wife to one of the family of the tribe of her father, so that every one of the people of Israel may possess the inheritance of his fathers. So no inheritance shall be transferred from one tribe to another; for each of the tribes of the people of Israel shall cleave to its own inheritance.”‘”

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  15. @sean – “To me altruism is actually helping someone else *at some cost to oneself*.”

    yes. like in the traditional arab pastoralist society in which young men herded the goats and protected them from the young male goatherders of other tribes. being aggressive in this scenario — on either side of the equation, either stealing or protecting goats — could be altruistic towards the group since the young males put themselves at risk while acquiring extra goats for the family.

    transfer these aggressive, “steal-some-goats” behavioral patterns to a larger picture, and you might get one or two tribes conquering large areas (and spreading their y-chromosome at the same time) — to the benefit of the familial groups (i.e. the tribe — well, to their closest family members, but indirectly the tribe), but at the loss of some of the individual males who would be killed along the way during the conquest.

    this is altruism. this is what we’re talking about.

    @sean – “I think in a fbd marriage system the man with a Y chomosome for being actually altruistic to relatives, is going to to be at a disadvantage to relatives who don’t have the same Y chromosome.”

    i have no idea what you’re talking about here. the whole point of an (ideal) fbd marriage system is that all the male relatives have the same y-chromosome. didn’t you read the post?

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  16. @sean – “it it seems to me – just an intuition – that genes for both altruism and aggression on the Y chromosome would not create much of a pressure for FBD marriage….”

    i haven’t said that. nobody has said that. you’re … i dunno what? … imagining things again. or having reading comprehension problems. i really don’t know.

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  17. I was just thinking out loud about your example. In a fbd marriage system the man with a Y chomosome for being actually altruistic to relatives, is going to to be at no disadvantage to relatives who have the same Y chromosome. But that fortunate situation will be once the FBD system is up and running. How does the altruism- conferring Y chomosome get to be predominant in the first place when those with it would originally be being altruistic (ie putting themselves at risk) for relatives who have different Y chromosomes and don’t reciprocate by sticking their necks out for Mr Nice G?uy

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  18. @sean – “How does the altruism- conferring Y chomosome get to be predominant in the first place when those with it would originally be being altruistic (ie putting themselves at risk) for relatives who have different Y chromosomes and don’t reciprocate by sticking their necks out for Mr Nice G?uy”

    it doesn’t. until the inbreeding happens. that’s THE WHOLE POINT.

    Reply

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