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.)

so why DID the japanese quit marrying their cousins?

one of the reasons seems to have been that the policy was, indeed, part of the modernization/westernization move in late-nineteenth century japan (sort-of the opposite of what happened in the maghreb/mashriq/parts of south asia when they went through an arabization process — oops! — bad luck).

from “Japan’s Outcaste Abolition: The struggle for national inclusion and the making of the modern state” [pgs. 82-83] (the “new commoners” referred to here are the burakumin whose social status changed with the “edict abolishing ignoble classes” — they were literally new commoners after moving up in the world [theoretically anyway]. “eta” also=burakumin. links added by me.):

“[O]ne of the main government aims of the time was to improve the national stock so as to maximize economic productivity and military power, as expressed in the slogan ‘rich country, strong military’. Although eugenics as a scientific discipline was not introduced into Japan until the end of the Meiji period, the Meiji government had from its inception followed policies to foster stronger and healthier Japanese bodies through its encouragement of milk-drinking and meat-eating, as well as through its public hygiene and health policies. If there was a hereditary and inferior Eta nature that was biologically transmitted, then it would be in the national interest to minimize relationships between New Commoners and others.

“The leaders of the semi-official Greater Japan Private Hygiene Association, whose purpose was to improve the nation’s human resources and to heighten people’s value as labour and military power, made explicit this connection between state interests and individual health. At this body’s inaugural assembly in 1883, its president and the future head of the Japanese Red Cross, Sano Tsunetami (1822-1902), declared that, ‘the health of each of us is related to whether our country shall be strong or weak, rich or poor’. Another executive, the medical doctor Hasegawa Yasushi (1842-1912), pronounced that the association’s aim was to ‘make the nation healthy, foster the strength that is the font of capital, […] and thereby increase militarisation’.

“Intellectuals debated precisely how the state might realize the goal of improving its human resources. Based on notions of a racial hierarchy topped by Westerners, holders of one extreme view proposed that Japanese people should interbreed with Western people. ‘The physiques and minds of Japanese are inferior to Westerners’, one writer argued, going on to propose that ‘we should import [Western] women…”

heh! (~_^)

“…and promote meat-eating to further improve our race’. While the latter idea about eating more meat proved popular, the former proved contentious. Hozumi Yatsuka attacked plans for racial interbreeding on the grounds it would adversely affect ancestor worship, a practice that in his opinion underpinned the Japanese nation.

“In somewhat more scientific fashion, the pre-eminent conservative intellectual Kato Hiroyuki pointed out in 1887 that if Westerners were racially superior and their genes dominant, then rather than improving the Japanese race, intermarriage between Western women and Japanese men would lead logically and unacceptably to the eventual replacement and disappearance of Japanese. Partly as a result of such criticisms, Japanese scholars ‘tended to emphasise environmental elements over genetics’, and devised practical plans to improve the population by reforming and improving people’s lifestyles.

People who looked at ways to reform popular lifestyles from the perspectives of national health and state power turned their attention to improving sanitation and diet and also drew attention to the problem of ‘inbreeding’ or marriages between close blood relatives. They considered inbreeding practices to be widespread, and thus to pose a serious problem, since they gave rise to disease and deformity, and ultimately would bring about ‘racial decline’. In light of these unwanted effects, intellectuals and officials called on people to desist from such unions.

“There had been occasional attacks on inbreeding during the early Meiji years. In 1875, Minoura Katsundo (1854-1929), a student of Fukuzawa Yukichi, had bemoaned the fact that alliances between close blood relatives were causing aristocratic degeneracy. Such claims were countered, however, by arguments that inbreeding was necessary to maintain the purity of aristocratic bloodlines. But growing out of a more general concern with ‘racial improvement’ among the socio-political elite, the concern with inbreeding that emerged in the latter part of the Meiji period was much broader in its focus, and it was given legal grounding by the 1898 Civil Code, which prohibited marriages between close relatives.

my questions are: first, what does “close relatives” mean? presumably first cousins anyway. then, how well was this civil code enforced? or was it changed at some point? or did the japanese not have to register their marriages with the state? or were there a lot of exemptions or something? because if there was a law banning cousin marriage in japan, why then were 22.4% of marriages in japan in the 1910s-1920s between cousins? (i actually saw a figure of 50% in something i was reading yesterday — need to find it again.) lots of looking the other way by officials? bribery? what was going on?

more from the book:

“A noteworthy aspect of the mid-to-late-Meiji anti-inbreeding campaign was that writers alleged that practice to be prevalent among New Commoners. Their claims may have had the effect of discouraging some people from inbreeding practices, as presumably the threat of becoming alike to New Commoners constituted a powerful disincentive. Such claims may have had some basis in the fact that discrimination limited the marriage pool of New Commoners and thus promoted community endogamy. But to target New Commoners as particular practitioners of this ‘offence’ was to ignore the fact that marriage relations between close relatives were not all uncommon among the population generally, and were prevalent especially among the upper reaches of society.”

previously: japan – reversal of fortune? and historic mating patterns in japan

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italy – reversal of fortune?

who knows?

but italy could be another place to look for a possible rapid inbreeding drop-off/rapid iq increase connection (see yesterday’s post) just ’cause the consang data are available. and they did, indeed, have a pretty rapid decrease in cousin marriage rates — at least in northern italy — not so much in the south. (i can’t think of any other examples where consang data are readily available — i mean without delving into church records or something like that.)

no idea if there are any early iq data available for italy, though. i won’t be looking for them (iq questions? – meh) — just wanted to let anyone who might be interested know that the numbers for the drop in inbreeding do exist for italy. (^_^)

look for the consang data here: Consanguinity, Inbreeding and Genetic Drift in Italy (tables also available here).

i put together a table of the first and last lustra in cavalli-sforza’s data set for a previous post, but there are data for each lustrum in between, too. you can get an idea of the scale of the drop-off (in the regions where there was a drop-off) from my nifty table:

1st cousin marriages - cavalli-sforza

previously: japan – reversal of fortune?

(note: comments do not require an email. italian family.)

japan – reversal of fortune?

a couple of months ago, greg cochran wrote about how a population (any given population) might raise its average iq quickly — like over two or three generations. one possible method, he suggested, was to quit inbreeding. here’s what he said:

“I’ve been thinking, off and on, about sudden changes in the cognitive abilities of populations: groups low suddenly scoring much higher or lower on a time scale too short to be explained by selection: say, three generations or less…. I can think of two perfectly feasible strategies that *would* cause significant one-generation increases in intelligence, in certain populations. Iodine supplementation, in places where it’s short, has a big payoff…. The other practical, low-tech strategy would be stopping cousin marriage. The next generation would be in much better shape, since the children of first cousins take a substantial IQ hit – maybe six points or so.

i think i may have stumbled across an example of a population rapidly dropping cousin marriage and, also very rapidly, gaining iq points.

japan.

yesterday, i was working on a completely different post about japan and cousin marriage, when i rediscovered this [pg. 30] (click on chart for LARGER version):

japan consanguinity rates - decline

that’s the decline in the average national consanguinity rates in japan from 1947 to the early-1980s. but the consang rates were even higher in the 1910s-1920s at 22.4% [pg. 29] (and who knows how high the rates might’ve been even further back?), so the chart above should look something more like this (pardon my crayola — and note that i just eyeballed it — click on chart for LARGER version):

japan consanguinity rates - decline - crayola 02

when i rediscovered this yesterday, i remembered what greg had written, and got to wondering if there were any historic data for japanese iqs and if there’d been any changes in those iqs over time. so i googled (as one does) … and found this:

The Rise of National Intelligence: Evidence from Britain, Japan and the U.S.A. [pdf] – lynn and hampson.

from that article [pgs. 27-31]:

“It has been possible to find five studies providing evidence on the secular trend of intelligence in Japan for the post World War II period….

“(1) Ushijima’s study (1961)….

“Here the Ushijima intelligence test was administered to 1365 children in 1953 and to a comparable sample of 1370 children in 1960 with the objective of determining any change in the mean over this relatively short period. The children were aged 9-15 years.

“(i) All age groups show a rise in scores for all abilities. The overall mean increase was 0.66 standard deviations, the equivalent of 9.9 IQ points, and representing an IQ gain of 14.1 IQ points per decade. This is of course a very considerable increase and much greater than anything found in either Britain or the U.S.A.

“(ii) The IQ increases are in general greater among the younger age groups than among the older….”

see my crayola chart above. kids who were fifteen in 1953 would’ve been born way back in 1938 when the consang rates were above 15% — maybe 17 or 18% (remember, i just eyeballed it, so this is a complete guess really) — while kids who were nine in 1953 would’ve been born in 1944 when consang rates were hovering right around 15%, in other words lower. same for the later cohort from 1960: fifteen year olds would’ve been born in 1945, nine years old in 1951. the younger the kids in the cohorts, the less chances their parents were related.

more from the article…

“(2) Kaneko’s study (1970)….

“Kaneko’s invetigation of a possible rise in the scores on this test was carried out in 1963….

“Hence the mean IQ in these schools has risen 10.38 IQ points over the 9-yr period … represents an IQ gain of 11.4 IQ points per decade. This figure is evidently broadly similar to the rise of 14.1 IQ points per decade for 1953-1960 found by Ushijima and confirms a very considerable rate of IQ gain in Japan in these early post World War II years.

“(3) Sano’s study (1974)….

“It will be seen that in all samples there were considerable increases in mean IQ from 1954 to 1972. The increases appear to be a little greater among the city children than among those from the prefrecture. When the results for 10- and 11-yr olds are combined, city children gained 18.04 IQ points and prefrecture children 15.07 IQ points….”

that the city children had greater gains than the rural kids is not surprising if inbreeding is the factor making the difference here. even up to the 1980s, consanguinity rates have been quite a bit lower in urban areas in japan as compared to rural areas (see table in this post for example). (more on this soon in that upcoming post on japan.)

“The average of the two gains is 16.56 IQ points, representing a gain of approx. 9.15 IQ points per decade for the entire sample.

“Sano also considered the question of whether the IQ gains in Japan have been increasing at a constant rate. For this he used Kaneko’s 1964 data which were available for two of the schools. He calculated that the increase in mean IQ was 10.47 points for 1954-1963 and 3.42 for 1963-1972…. ([I]t will also be noted that the gain of 10.47 IQ points for 1954-1963 is closely similar to Kaneko’s figure of 10.38 for the same period.)

“It is apparent therefore that there was a considerable deceleration in the rate of increase in intelligence over the period 1954-1972….”

again, see my crayola chart. the decline in cousin marriage rates is much sharper in the decades preceding 1954 than during those preceding 1963. in other words, there was a deceleration in the reduction of cousin marriages over time, so perhaps we shouldn’t be surprised at a deceleration in the increases in iq over time.

“(4) Wechsler studies….

“Thus after making these adjustments we have Japanese mean IQs of 101.9 for 1951 and 107.4 for 1975. Hence over this 24-yr period (1951-1975) the Japanese mean IQ increased by 5.5 IQ points relative to the American IQ…. This represents a Japanese IQ gain of 5.75 IQ points per decade. This rate of increase for the period of 1951-1975 is somewhat less than Sano’s result of a 9.15 IQ point per decade increase over approximately the same period (1954-1972)….

“A second Japanese study using the WISC and WISC-R is also available (Anon, 1981)…. This gives a rise of 20.03 IQ points over the 24-yr period, making 8.34 IQ points per decade….”

lynn and hampson conclude:

“The conclusion of the Japanese studies is as follows. Two studies of the early post World War II period show substantial IQ gains of 9.9 and 11.4 IQ points per decade. Three studies of a longer period from approx. 1950-1975 show lower IQ gains of 9.1, 8.3 and 5.7 IQ points per decade, giving an average gain of 7.7 IQ points per decade. Since the early part of this period was characterized by a greater rate of gain, it appears that since around 1960 the IQ gains in Japan have decelerated to approx. 5 IQ points per decade….

“It is not particularly surprising that the Japanese gains should have been the greatest of the three countries. Japan was a relatively underdeveloped country in the 1930s with a per capita income about one eighth of that of the U.S.A.”

but the country was probably relatively underdeveloped because the japanese had a lower average iq at the time, and it’s since increased phenomenally … due to the sharp and rapid decline in inbreeding in japan? and so has their economic success obviously.
_____

i’d be curious to know two things:

– why did the japanese quit marrying their cousins? was there some official policy out there discouraging it — as part of their general modernization, “be more like the westerners” move? did the people just naturally adopt it as part of that westernization package? was it connected to christianity in japan? (japanese catholics historically had lower first cousin marriage rates than other religious groups — i’ll get to this in my upcoming post on japanese cousin marriage — the one that i was working on yesterday!). was it related to industrialization and urbanization? all of the above? none of the above?

– has something similar happened in china and/or korea (or elsewhere for that matter — i mean in modern times)? the cousin marriage rates for china are reportedly very low — today — but i’m pretty sure they were much higher in the past — even the recent past (see mating patterns in asia series below ↓ in the left-hand column), but i don’t have as good data for china as what i’ve presented here for japan. but inquiring minds want to know!

see also: Reversal of Fortune

previously: historic mating patterns in japan

(note: comments do not require an email. cool japanese people!)

i found it!

i said:

“robin fox, for instance, in The Tribal Imagination (and, i suppose, in his incest book, but i haven’t read that) mentioned that, in father-daughter incest cases, the majority of those relationships are initiated by the daughter.”

redzengenoist asked for a reference, which then i couldn’t find — but now i found it! and it goes to show — you should always ask for a reference! from The Tribal Imagination [pg. 152]:

“In both stories the initiator is the girl, like Lot’s daughters. This is far from the ‘patriarchal’ situation usually envisaged with dominant males sexually exploiting helpless females, as Amnon and Tamar. The poet sees incest as a dangerous female impulse; the men are the horrified victimes. Ovid is almost Wahhabist in his fear of female lust. But this is in line with the fact that in cases of consummated incest the female often is the initiator, and with the classical and ancient world’s depiction of women (some women) as assertive, and as taking the initiative in matters sexual.”

obviously, “often” (what fox said) does not equal “the majority” (what i remembered).

boy, do i have a lousy memory! (*hbd chick blushes*) please, please, always ask me for a reference if i haven’t given one!

(note: comments do not require an email. can’t remember anything anymore….)

theories

so i think the connection between inbreeding (or outbreeding) and the evolution of the “innate social aptitudes of man” [pdf] works something like this:

inbreeding in and of itself does not change the frequency of genes (alleles) in a population [pg. 65], but it does move them around, concentrating them in certain family lines.

if, then, some sort of genetic mutation arises in one family line which, let’s say for the sake of argument, results in the carriers somehow behaving more altruistically towards their fellow family members than strangers, and this results in them being able to increase their inclusive fitness, then that genetic mutation will be selected for.

it will really be selected for (i.e. the selection rate will be accelerated) because of the inbreeding because: 1) since the inbred family will have greater than average numbers of this “altruism gene” because it is inbreeding, its members will likely execute a greater total number of altruistic behaviors towards one another and, so, they will really benefit fitness-wise from this new gene. also, 2) perhaps — perhaps — all else being equal, the inbred family members will feel even more strongly altruistic towards their fellow family members than an outbred family would since they are so much more genetically similar to their family members. to be honest with you, i’m not so sure about that second proposition, so i’m just going to skip it for now and focus on the first one.

wrt the first proposition, that the rate of selection of “genes for altruism” is faster in an inbreeding population is exactly what wade and breden found when they ran some models — the more inbreeding, the more rapid the selection of the altruism genes:

you can imagine why.

if you have a bunch of different families in a population, and one of those families possesses some sort of “familial altruism” gene which means that its members help each other out (or whatever) more than the members of the other families do, and this increases the fitness of a majority of this special family’s members, then they are simply going to be more successful than the other families. they’ll leave more descendants behind and, thus, more of those genes behind. IN ADDITION, if this successful family ALSO inbreeds, each of its members is much more likely to have at least one, or even two, copies of this familial altruism gene, so more members of this successful family will be even more altruistic to each other and voilà! — they’ll increase their fitness and success even more than they would have done without the inbreeding.

these familial altruism genes — genes that lead to behaviors in which individuals somehow favor their own family members over non-family members — and by family members i mean extended-family members — are only going to arise, of course, in a population in which there is more than one family. if you’ve got some tiny band somewhere that has absolutely no contact with any other group (doubt that’s ever existed), then my evolutionary scenario simply won’t happen. it’s the competition between the individuals from the different families that is driving this.

naturally, genes in any population — even an inbreeding one — won’t remain restricted to any one family for very long. no family anywhere inbreeds 100% exclusively, so if some successful familial altruism genes do arise in some inbreeding family somewhere, they will quickly spread to the other families in that population. thus, there is probably an ongoing familial altruism genetic arms race in inbreeding populations.

also, i think fewer familial altruism genes — or not such strong ones, perhaps — are going to arise in a comparatively outbreeding population. the accelerated selection due to the inbreeding won’t be there, nor will this arms race to keep one step ahead of the joneses when it comes to familial altruism. additionally, i think that in an outbreeding population, there’ll be greater selection pressures than in an inbreeding population for “reciprocal altruism” genes — i.e. genes which lead people to be willing to cooperate more with non-family members — since more of those sorts of behaviors will likely be required to be successful in life.
_____

so what do these “familial altruism” genes look like?

i dunno.

maybe there are differences in oxytocin-related genes? — the luuuuv hormone that “turns out to be the hormone of the clan.”

or — ya’ll know that i’m kinda fascinated by interclan fighting which is the flip-side of being nice to your family (i.e. be extra un-nice to your non-family) — so maybe one familial altruism gene is the “warrior gene” (MAO-A gene)? dunno.

one that i speculated about before is CYP21A2, the gene connected to congenital adrenal hyperplasia (CAH), a recessive genetic condition which affects the production cortisol which, in turn, affects the production of androgens (like testosterone) — notably, in the most common form of CAH, androgen levels are increased. the condition is a recessive one, so you need to have two copies of the deleterious allele to have the condition, but as i mentioned in my previous post on CAH, carriers with one copy of the allele have been found to have excess androgens — and androgens have been connected to aggression. (also, children with CAH have been found to have smaller amygdalae, so … they’re less fearful? don’t know if this also holds true for adults with CAH.)

increased aggression? fighting at the drop of a hat? interclan fighting? see where i’m going with this?

the interesting thing is — at least i think it’s interesting — is that there are different frequencies of CAH found in different populations. what we’d really want to know, of course, are the gene frequencies for CAH for different populations, but in lieu of those … here are some incidence rates of classical CAH in different populations [numbers acquired from or via here and here]:

1:282 – Yupik Eskimos, Alaska
1:2,141 – La Reunion
1:4,081 – Western Australia Aborigines
1:5,000 – GLOBAL
1:5,000-7,000 – Moroccan Jews
1:5,041 – Zurich, Switzerland
1:7,000 – Kuwait
1:10,866 – France (Whites)
1:10,866 – Italy (Whites)
1:11,500 – Sweden
1:11,764 – Netherlands
1:14,300 – Hungary
1:14,403 – Croatia
1:14,500-23,344 – New Zealand
1:14,869 – Western Australia
1:15,518 – Emilia-Romagna, Italy (Whites)
1:15,800-18,000 – Japan
1:17,098 – Scotland
1:19,939 – Minas Gerais, Brazil
1:20,000 – Norway

i dunno, but i see — maybe — the more inbred clannish fighters (yupik eskimos, moroccan jews, kuwaitis) having more cases of CAH than the more outbred peaceniks (new zealanders, norwegians, even northern italians). also…

“The Texas data indicate a lower disease frequency in African-Americans when compared with Caucasians, and international data indicate higher frequencies in native Yupik Eskimos, Brazilians, residents of La Reunion, and Filipinos.” [source]

“The prevalence of the disease [non-classical CAH] in Ashkenazi Jews was 3.7%; in Hispanics, 1.9%; in Yugoslavs, 1.6%; in Italians, 0.3%; and in the diverse Caucasian population, 0.1%.” [source] (non-classical CAH refers to a less severe form of CAH which might not get noticed until adulthood when it expresses itself in features like a woman having, perhaps, a bit too much facial hair.)

again, what we’d really want to know are the gene frequencies for CAH in different populations. then the über-human savants that we call population geneticists could do their math wizardry to see if these genes were under positive selection or not (zey hav vays av mayking ze data talk). (another interesting thing, btw, is that there are many different mutations in this gene which cause a range of CAH conditions from mild to severe — and different mutations are more common in different populations — see here and here and here for instance.)

of course, maybe these mutations in CYP21A2 aren’t being selected for for increased aggression/upside-down familial altruism. maybe it’s something else. witchel, et al., found that heterozygotes for mutated CYP21A2 alleles (i.e. individuals with just one copy of the cr*ppy gene) had increased cortisol levels and cortisol is, apparently, important for the immune system, so maybe these mutants simply survive infections better. others have found a possible connection between higher iq and CAH (masculinization = higher iq?) — see here and here and here — so maybe that’s it.

or maybe these genes are not being selected for at all. however, fertility rates of people (women) with CAH are low, so it seems like a strange bunch of genes to have around if they don’t have some sort of benefit.

previously: inbreeding and the evolution of altruistic behavior and looking for altruism genes and visions of altruism genes

(note: comments do not require an email. CAHt.)

mating patterns in colonial mexico: yucatec maya population size

here we go. from Maya Society under Colonial Rule: The Collective Enterprise of Survival [pg. 59], three sets of yucatec maya population size estimates/educated guesstimates (take your pick!) for the colonial period (click on chart for LARGER view):

i thought i could combine these numbers with restall’s info on mayan family/mating patterns, which are based upon census and testamentary records, and see, maybe, just how close the mating patterns were amongst the colonial maya. here’s what restall had to say:

– there were a total of 270 patronym groups (chibalob) in the yucatan living in 200 communities (cah).
– a typical cah would have had 30-40 patronym groups in it.
– a typical family would have marriage alliances with four or five other patronym groups.
– people generally didn’t marry outside of their cah (village, barrio, community).

you had to marry outside your patronym group, and it’s likely that a good number of marriages were between maternal cousins (i know – i haven’t posted about this yet – sorry!). it was probably the preferred form of marriage anyway, although that doesn’t mean that everyone married a maternal cousin.

how many individuals are typically of reproductive age in any given society? were in colonial maya society? i have no idea. let’s assume — and this probably wasn’t true — but let’s assume that they had a stable population — not expanding, not contracting (just for the sake of argument). if we divy up the population’s age cohorts by five — 0-5, 5-10, 10-15, etc. — going up to, let’s say, age 70, we’ve got 21.4% of the population in the 10-25 marrying age range. (the colonial maya weren’t polygamous, btw — the pre-columbian aztecs were though.)

so — 200,000 maya in 270 patronym groups = ca. 740 individuals in each patronym group. 21.4% of that gives you ca. 158 people of reproductive age per patronym group. an equal number of men and women? maybe, maybe not — but let’s say yes, so that’s ca. 79 reproductive men and women per each patronym group. and your patronym group was connected to something like five others according to restall, so that’s a potential 395 individuals you could marry. sounds pretty good!

but remember, the maya usually didn’t marry outside their cah. that’s 200,000 people across 200 cah, so 1,000 people in each cah. divided between 30-40 patronym groups — let’s call it 35 — so 28-29 individuals in each patronym group in each cah. 21.4% of those are in the marriage age range = six individuals (three men, three women). times the five patronym groups that your patronym group is allied to leaves you with just 15 possible spouses for you to choose from. that’s a pretty narrow range. generation after generation.

and chances are, people would’ve married one of their maternal cousins anyway.

colonial yucatec maya marriage patterns, over a three-hundred or so year period (1550-1850), were probably either quite inbred and/or very endogamous.

previously: mating patterns in colonial mexico: the mayans

(note: comments do not require an email. yucatec maya gentleman. (^_^) )

the flatlanders vs. the mountain people

**update below**

following up from this

“These data again demonstrate the political role of preferred marriage forms. Exogamy and lack of cousin marriage within large lowland nation-states aid in uniting disparate clans and villages. By contrast, the absence of exogamy and the presence of preferred cousin marriage intensify relationships within the small upland social units.”

…where in the world should we expect to find cousin marriage/inbreeding/endogamy vs. lack of cousin marriage/outbreeding/exogamy? note that i think this lowland/upland dichotomy particularly applies to agriculturalists vs. agri-pastoralists/pastoralists and (maybe) not so much to hunter-gatherers, so i’m ignoring hunter-gatherers for right now. (click on map for LARGER view):

>> inbreeding <<

– saudi arabia, yemen, oman, uae: check. especially, once-upon-a-time (i.e. before the spread of islam), in the western and southern regions of the arabian peninsula. dunno if that is true or not.

– the middle east: check. but not, once-upon-a-time (i.e. before the coming of islam?), in egypt. dunno if that is true or not.

– turkey, iran, turkmenistan, afghanistan, pakistan: check.

– southern, but not northern, india: check.

– ethiopia, most of east africa heading southwards except for coastal areas: the amhara of ethiopia (and ethiopian jews) have rules against close endogamy, but that’s probably/possibly largely a result of the introduction of christianity. other groups in ethiopia certainly practice endogamy. dunno about the rest of east africa.

– nepal, bhutan, other groups in the himalayas: i happen to know that the nepalese have a tradition of cousin marriage, just haven’t gotten around to posting about it yet. dunno about bhutan or other himalayan folks.

– northern parts of southeast asia, vietnam (talk about very stubborn guerrilas!), northern thailand: check.

– indonesia: more on borneo than most of the other islands. no idea.

– southern and western china, but not northeast china (including manchuria): my impression from the reading so far is that clans, so probably the cousin marriage that definitely occurred/s in china, were historically more prevelant in southern than northern china. further research is required. (~_^)

– japan: check.

– southern europe: spain, southern france, central and southern italy including sicily and sardinia, greece, the balkans — check, check, check, check, check. if you haven’t already, see mating patterns in europe series in left-hand column below ↓.

– alpine countries: switzerland, austria, etc. not sure.

– northern europe: scotland, wales, parts of ireland, norway. — check, check, check, not sure. again, see mating pattern in europe series.

– russian federation (better map here): from the urals westwards generally yes, although there are patches of lowland areas in the west. the west siberian plain should be a large area of outbreeding until you get to the central siberian plateau (unless western russians settled there bringing their marriage traditions with them?). dunno the details.

– north africa: esp. in the atlas mountains. not sure what the berber mating patterns were pre-islam. the cousin marriage rates are high today.

>> outbreeding <<

– northern europe: england, northern france, belgium, the netherlands, denmark, northern germany, northern poland — check, check, check, check, check, check, more-or-less. especially since the medieval period, but there was most likely cousin marriage/endogamy in all of these places pre-christianity. see mating patterns in europe series.

– iraq: around the tigris and euphrates — the garden of eden. lots of inbreeding, in fact, but that may have been introduced by the arabs along with islam — certainly father’s brother’s daughter (fbd) marriage likely was. dunno what the marriage practices of the populations there were pre-islam. i wonder what they were in ancient sumerian, etc., times? dunno.

– large parts of west africa: dunno. there appears to be some high cousin marriage rates in parts of guinea and nigeria, but that’s just where there are some highlands in west africa. dunno for sure.

– central africa: niger/chad area. dunno.

– coastal east africa: dunno.

– libya and egypt: pre-islam. dunno.

– northern india: check. relative to their neighbors anyway.

– parts of russia: see comments above in inbreeding section.

– northern china: see comments above in inbreeding section.

– parts of southeast asia: check.

– parts of indonesia: in particular the southeastern part of sumatra. dunno.
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**update 09/14: oops — forgot the new world (remember – agriculturalists only):

– western/southwestern north america, mesoamerica, anybody in the andes: should’ve been inbreeders. dunno for sure.

– eastern north america: groups in the midwest ought to have been outbreeders, relatively speaking. anybody in appalachia ought to have been inbreeding. florida groups (were they agriculturalists?) should’ve been outbreeders — according to this theory anyway. dunno for sure.
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previously: this one’s for g.w.

(note: comments do not require an email. where the inbred martians should be.)