life history and cousin marriage

**update: correction to post (about halfway down) – see also comments. thanks, matt!

check this out! [some excerpts from the paper]:

“A slow life history is related to a negative attitude towards cousin marriages: A study in three ethnic groups in Mexico”

“The sample consisted of 205 respondents from three rural ethnic groups. Half of the sample (51%, n = 103) were indigenous Mixtecs, 17% (n = 35) were Blacks, and 32% (n = 65) were Mestizos (for two participants the ethnic background was unknown). A large majority (94%) was Roman Catholic. There were about equal numbers of males (n= 100), and females (n= 105), and the sexes were nearly equally distributed over the three ethnic groups. The mean age in the sample was for women M = 44.79 (SD = 8.09), and for men = 49.85 (SD = 9.91). For the following percentages, because of rounding off and missing values, the total percentage is sometimes different from 100%. Most women (90%) were homemakers, 5% had a profession, and 6% indicated not to have a profession. Of the men, the large majority (74%) were farmers, 10% were fishermen, 16% had a variety of other professions, and 2% indicated to have no profession….

“The questionnaire consisted of 9 items, 4 of which expressed a negative, and 5 of which expressed a positive consequence of marrying a cousin. At the beginning of the questionnaire, participants were presented with the statement ‘Marrying a cousin….’ Then the 9 items followed. The five positive statements included 1) means that you marry someone with the same values; 2) enhances the unity in the family; 3) keeps wealth in the family; 4) makes it easier to get along with your spouse; 5) makes your marriage more stable. The four negative statements included: 1) may lead to children having a high risk of defects; 2) is wrong for religious reasons; 4) leads to family conflict; 5) leads to a relationship without passion. Participants were asked to indicate on a scale from 1 (extremely disagree) to 5 (extremely agree) how much they were in agreement with the 9 statements….

life history and cousin marriage - table 01

“A closer look at the participants’ ratings of the statements (Table 1) reveals that participants reported to be in the least agreement with most positive statements; on average, they disagreed that marrying a cousin would enhance the unity in the family, would keep wealth in the family, or would make it easier to get along with one’s spouse. On average, participants were neutral with respect to the statement that marrying a cousin would mean that you would marry someone with the same values. They were on average most, and very much, in agreement with the statement that marrying a cousin is wrong for religious reasons, nearly as much with the statement that marrying a cousin leads to family conflict, and somewhat less with the statement that marrying a cousin would lead to relationship without passion. It is noteworthy that the notion that a marriage with a cousin would result in children with a higher risk of mental and physical defects was considered relatively unimportant….

Overall, as predicted, with increasing levels of a slow life history strategy, the attitude towards marrying a cousin was more negative, β = -.30, t (189) = 4.24, p <.001. Separate analyses within the three ethnic groups showed that this was especially true for the Mixtecs, β = -.30, t (95) = 3.14, p = .002, and the Blacks, β = -.35, t (29) = 4.30, p < .001, but not at all for the Mestizos, β = -.07, t (59) = .57, p = .57….

The results demonstrate that participants overall had a negative attitude to marrying a cousin, and that the three ethnic groups did not differ in this respect. Unlike what is often assumed, the main objection against marrying a cousin was that it is wrong for religious reasons, and the risk of genetic defects of children born out of such marriages was considered relatively unimportant. In line with this, we found that, albeit only among men, marrying a cousin was viewed more negatively the more religious one was. Cousin marriage was neither considered to contribute to the quality or unity of marriage and the family. These findings may suggest that the attitudes towards such marriages differ from those in Western cultures where especially the risk of genetic defects of offspring is considered important (Ottenheimer, 1996), as well as from those in Eastern populations where cousin marriages are considered to preserve the unity of the clan and the family (cf. Jaber et al., 1996). Furthermore, as predicted, we found a sex difference with women having overall a considerably more negative attitude towards cousin marriage than men. This is in line with parental investment theory (Trivers, 1972). Since females invest the most in conception, birth and postnatal care, investing in a potentially unviable offspring is extremely costly. Therefore, women may be more concerned that marrying a cousin leads to children that have a higher risk of being mentally and physically handicapped….

Our findings clearly suggest that especially in this population, more negative attitudes towards cousin marriages do reflect primarily a slow life history strategy, characterized by typical features such as good executive functions, positive relationships with one’s parents, low mating effort, lower levels of risk taking, higher levels of foresight and planning, and more persistence and self-directedness. Individuals with this type of strategy do seem to be relatively less inclined to run the risk of having offspring with genetic defects because of mating with kin. From a theoretical point of view this slow life history strategy maximizes long-term reproductive success (e.g., Figueredo et al., 2006; Kaplan and Gangestad, 2005) by having fewer, high quality, offspring rather than having numerous lesser quality offspring, whose reproductive success depends more on luck….

“While we did not find differences between the ethnic groups in their attitudes towards cousin marriage, the effect of life history strategy was not only apparent among the Mixtecs, but also among the Blacks. However, it was not found among the Mestizos….

An additional finding was that, overall, those who approved of controlling the mate choice of their offspring had a more positive, or less negative, attitude towards cousin marriage. This suggests that, as expected, in general, fostering marriages with cousins may be the ultimate consequence of the preference to control the mate choice of one’s offspring by selecting in-group members as mates for one´s offspring. Indeed, a plethora of studies shows that in a wide variety of cultures, a major concern of parents is that the mate of their offspring comes from the same group (e.g., Buunk et al., 2008). A prime example of this are the various Islamic cultures such as Iran and Saudi Arabia where parents determine to an important extent whom their offspring marries, and where cousin marriages are very common (Jaber et al., 1996). One of the benefits of having one’s offspring marry a cousin is that family and clan alliances are strengthened, and loyalty from one’s son and daughter-in-law better safeguarded.”
_____

so, buunk and hoben seem to have found that:

– individuals with slow life histories (the individuals formerly known as the K-selection people) tend to avoid cousin marriage whereas those with fast life histories (or the r-selection people) really don’t care one way or the other
– women want to avoid cousin marriage more than men (at least in mexico)
mixtecs and blacks (slow life history) mestizos in mexico are less squeamish about cousin marriage than mestizos (slow life history) mixtecs and blacks
– all three of these groups generally avoid cousin marriage on religious grounds (the vast majority being roman catholic).

neat!

nowadays, the cousin marriage rates in mexico are very low — last time anybody checked (in the 1960s) the average rate across the country was 1.3% [pdf]. that’s loooow.

i haven’t yet looked much into the histories of mating patterns in mexico — and i haven’t looked at all at the mixtecs — mostly the mayans (see here and here for example). but if the mixtecs were anything like other pre-columbian, pre-christian latin american populations — the mayans or the aztecs or the taino in the caribbean — then they probably favored some sort of cousin marriage. i don’t know that for sure or not — i’ll let you know if and when i find out.

in fact, it’s likely that the roman catholic church dropped the prohibitions against cousin marriage beyond the first cousin limit for mexicans as early as 1537, which is ca. 400 years before the cousin marriage ban went to only first cousins for europeans. (i still have to check if this 1537 change was just for south americans or for all of latin america.) if this is correct, then mexicans have really only experienced a first cousin marriage ban since they converted to christianity in the 1500s+, rather than the second, third, and even sixth cousin marriage bans that europeans were subjected to starting in the 500s (or ca. 800s in more northerly parts of europe … or post ca. 1500 if you’re irish (~_^) ). in other words, europeans have probably been outbreeding more and for a longer period of time than most mexicans.

i’m not sure when mexicans started taking the church’s cousin marriage ban seriously. they had a habit of marrying very locally (i.e. in the barrio) right up until at least the 1950s (see here), so that could, of course, mean that they were marrying second and third cousins, etc., at least up until that point. mayan villages are typified by lattice networks of genetic connections between their residents — i don’t know if this applies to the mixtecs (or any other sub-populations of mexicans) as well, but i wouldn’t be surprised if it does.

buunk and hoben say: “Unlike what is often assumed, the main objection against marrying a cousin was that it is wrong for religious reasons, and the risk of genetic defects of children born out of such marriages was considered relatively unimportant…. These findings may suggest that the attitudes towards such marriages differ from those in Western cultures where especially the risk of genetic defects of offspring is considered important (Ottenheimer, 1996)….”

yes, buuuut — if you go back just two hundred years in europe, the reasons westerners avoided cousin marriage were almost purely religious. definitely if you go back to the medieval period. almost the entire reason for all of the outbreeding in the west is related to religious belief (conversion to christianity), although the secular powers that be also got involved. the concern about genetic/health defects really only started in darwin’s time (having said that, at least some people in late antiquity were aware of the health effects of too much inbreeding, too). so these differences are really just historic ones. westerners used to avoid cousin marriage for religious reasons, but now for many there’s just an automatic ewwww reaction, so official cousin marriage bans are almost not needed any longer.

this is some really neat research and a very cool paper! (^_^)

the only criticism i can level at the researchers is their apparent lack of awareness of the history of mating patterns in europe (don’t they read this blog?! (~_^) ). for instance, they said in the paper:

“For example, according to Kuper (2002), marriage between cousins was permitted in ancient Israel and was practiced in classic Greece and Rome. Although in the 4th century, Emperor Theodosius I introduced a ban on marriage between cousins, this practice continued and among the people attitudes were generally more or less neutral. Much more recently, in the 18th and 19th century in England, cousin marriages became increasingly accepted in especially the higher classes. Up until the middle of the 19th century, cousin marriage was permitted in the United States, and in many European countries. However, since the 19th century attitudes towards cousin marriage in the Western world began to change drastically. The main reason for this was that the progeny of cousins were believed to be inflicted with genetic defects and poor breeding, resulted in delays in progress within society (see e.g., Bittles and Neel, 1994).”

uh … no. they need to have a look at a couple of sources like goody or mitterauer or ausenda. or the “mating patterns in europe series” below ↓ in the left-hand column. (~_^)
_____

bonus: anonymous conservative has written a lot about r/K selection theory wrt politics — make sure to check out his website!

previously: mating patterns in colonial mexico: the mayans and mating patterns in colonial mexico: yucatec maya population size and structural endogamy and assimliation is a two-way street (or why endogamy means mexicans will find it hard to become middle-class anglos)

(note: comments do not require an email. i’m a lumberjack, and i’m ok!)

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23 Comments

  1. @hbdchick Nice reference. Of course the distinction is not made between first cousins and other cousins. Nobody seems much to like numbers. And the question was not raised, “Do you have more babies if you marry a cousin?” Kind of like selling a guy a house and not mentioning that it’s on fire, eh what?

    Reply

    1. @Gorrlieb “A study in Iceland conclude that marriage among third cousins are more fertile…” Yep. Lots of independent supporting evidence as well. Odd it’s not spoken of more.

      Reply

  2. good stuff

    .

    off/topic but related to life history ish

    although it may overlap in various ways i mostly think the increase and decrease of violent traits will have an independent dynamic to the inbreeding / outbreeding one (because non-outbreeding cultures seem to have undergone pacificaton also). however i did think of one way the hajnal line model could directly effect it.

    If we assume violent individuals are more likely to die as well as kill then early marriage and reproduction would compensate so in a hajnal culture where a man on average marries at age 26 a violent or risk-taking individual (as i think those traits are connected) is less likely to have reproduced than the same individual would have if he’d been married off at 16 i.e. in the hajnal system impulsive risk-takers have an extra ten years to do something impulsive and risky before they have a chance to reproduce whereas in an early marrying culture they may have reproduced already.

    For example, Irish Travellers (and i assume other similar groups?)

    http://en.wikipedia.org/wiki/Irish_Travellers

    “On average there are ten times more driving fatalities within the Traveller community. At 22%, this represents the most common cause of death among Traveller males.”

    Reply

  3. slow life history strategy, characterized by typical features such as good executive functions, positive relationships with one’s parents, low mating effort, lower levels of risk taking, higher levels of foresight and planning, and more persistence and self-directedness

    I’d be more interested if they had measured whether people actually had children and how young they had them.

    People with “slow” life history seem to marry earlier and have more children (earlier) than people with the “fast” life history in Western countries.

    hbd chick: mixtecs and blacks in mexico are less squeamish about cousin marriage than mestizos

    hbd chick, wasn’t the finding here was no significant group differences (“The three ethnic groups did not differ in their attitude towards cousin marriages”)? but with life history being differently predicting attitudes in group. If this is the case then fast life history blacks and mixtecs would, I guess, have more negative attitudes than fast life history mestizos (and amplified if there are group differences in life history speed).

    Also, interesting point re: the importance of health problems vs religion, but health problems are only really salient in the case of first cousins, dropping off relatively quickly, and they might be more aware of this, if the questionaires, etc. didn’t really make much distinction.

    Reply

    1. @Matt:

      “People with “slow” life history seem to marry earlier and have more children (earlier) than people with the “fast” life history in Western countries.

      Why do you say that?

      r-stragists may marry later, but they do tend to have kids much earlier… (think teen pregnancy)

      Reply

  4. Matt
    “People with “slow” life history seem to marry earlier and have more children (earlier) than people with the “fast” life history in Western countries.”

    That’s the point i’m making.

    It will depend on whether there’s a mismatch with the culture. People with a fast life history in a culture designed to support it e.g. Irish Travellers, marry and have childen very young. In a marriage culture designed to support slow life history then yes, individuals with a fast life history aren’t likely to build up the resources necessary for late marriage.

    Reply

  5. @matt – “hbd chick, wasn’t the finding here was no significant group differences”

    ack! yes. thank you! (never write a post in a hurry….)

    what i was thinking in my head when i read the paper was — oh, isn’t that interesting that slow life history blacks and mixtecs should be more squeamish about cousin marriage than slow life history mestizos, when the general pattern seems to be that fast life history peoples don’t really care about cousin marriage one way or the other, and blacks anyway (don’t know about mixtecs) generally have fast life histories. it’s interesting that the hesitation to marry a cousin with slow life history blacks then seems to be amplified. (and then it came out all backwards in the post. ack! blogging FAIL! (*^_^*) )

    Reply

  6. Without digging into this topic too deeply, it’s always been my understanding that the ban on sixth/seventh degree cousins was mainly an ecclesiastical attempt to discourage concentration of wealth and power among the aristocracy, with a flimsy rationalization in terms of the ban on incest. The church saw the secular aristocracy as competition to its own rule and discouraged the unification of vast land-holdings through strategic marriages. Their oppposition was partly self-serving, but also rationalized by opposition to greater inequalities of wealth and power.

    Reply

  7. @webe – “it’s always been my understanding that the ban on sixth/seventh degree cousins was mainly an ecclesiastical attempt to discourage concentration of wealth and power among the aristocracy, with a flimsy rationalization in terms of the ban on incest.”

    yeah, there’s probably something to that, and that’s the sort of economics argument that jack goody has made.

    all sorts of parties took advantage of these bans in ways that you might not expect beforehand: sometimes one aristocrat/royal would prevent the marriage of another aristocrat/royal on the grounds that the marriage would violate the cousin-marriage prohibition; sometimes aristocrats/royals would use the ban to get a divorce — if their wife didn’t produce an heir or if they just fancied someone else — on the grounds that, oops!, i didn’t realize she was my fifth cousin! sorry! (~_^)

    the sixth cousin ban was nutty, because probably no one could truly obey it. if you lived in a small village in medieval europe, how could you avoid marrying a distant cousin? who even keeps track of their fifth cousins?! (nobody.) and it was even crazier than you know, because you weren’t supposed to marry your sixth cousins-IN-LAW either! or in baptism. *facepalm* suddenly you really rule out EVERYbody in your village and all of the neighboring villages.

    what’s interesting about the sixth cousin marriage ban — or even the first or second or third — is that it/they were there at all — and that christians in europe did comparatively speaking avoid marrying their close relatives starting in the early part of the medieval period.

    also, i think some of the church fathers did genuinely view cousin marriage as a way to help build a more christian society here on earth. i’m sure there were plenty of popes and bishops and priests that were just interested in monetizing the whole system, but i think the idealists were there, too. and it was their idea first (i think). the rest just cashed in on it.

    Reply

    1. @hbd chiick “i think some of the church fathers did genuinely view cousin marriage as a way to help build a more christian society here on earth. ” That seems to me to be a well thought out position. But of course you know. You thourht it out.

      Reply

  8. @matt – “…health problems are only really salient in the case of first cousins, dropping off relatively quickly….”

    keep in mind that that really only applies in regularly outbreeding societies. if you’re saudi arabian, for instance, it can be dangerous to marry even a second cousin since, for many saudis, a second cousin can approach the equivalent of a first cousin — genetically speaking — in the western world.

    it’s probably not a concern for mestizos to marry second+ cousins, or even black mexicans, but i’d wonder about some of the smaller, close-breeding populations like the mixtecs. don’t know.

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  9. @linton – “And the question was not raised, ‘Do you have more babies if you marry a cousin?’ Kind of like selling a guy a house and not mentioning that it’s on fire, eh what?”

    heh. (^_^)

    Reply

  10. @jk – “Do read…”

    yup. =/

    i saw a post on gates of vienna where someone suggested boycotting britain as a vacation place. not a bad idea, really. but most likely not enough. not by half. =/

    Reply

  11. @grey – “i did think of one way the hajnal line model could directly effect it.

    “If we assume violent individuals are more likely to die as well as kill then early marriage and reproduction would compensate so in a hajnal culture where a man on average marries at age 26 a violent or risk-taking individual (as i think those traits are connected) is less likely to have reproduced than the same individual would have if he’d been married off at 16 i.e. in the hajnal system impulsive risk-takers have an extra ten years to do something impulsive and risky before they have a chance to reproduce whereas in an early marrying culture they may have reproduced already.”

    hey, that’s really good! i think you’ve got something important there!

    i think the pacification of europeans (dunno about the others, yet) had several factors including (but maybe not only) these:

    – the execution of criminals that henry harpending & peter frost have been talking about — just remove those individuals from the gene pool;
    – my outbreeding idea which reduces/eliminates the clannish infighting — and the individuals who are predisposed to that clannish infighting are just weeded out of the population (because their genotype is not selected for/needed any longer in a non-clannish setting);
    – now your idea that there’s a connection to age at marriage.

    cool! (^_^)

    Reply

    1. @hbd chick “the execution of criminals that henry harpending & peter frost have been talking about — just remove those individuals from the gene pool” Logical. But things may not be that simple. The genes in question are probably widespread in the population, assuming they exist. Otherwise for sure the memes are. So you take a bunch of young men out of the picture (execution, incarceration, transportation) and the women will still have the same number of children. Males are pretty easy to recruit. And in the next generation voila, the gene pool is smaller and the reproductive rate higher. You just enhanced the very part of the gene pool you were trying to suppress.
      Just a thought.

      Reply

  12. r-stragists may marry later, but they do tend to have kids much earlier…

    er… IIRC isn’t it that r strategists in the human population would those who have most kids (that’s the definition of r-strategy if it even applies to humans, having more kids and so investing relatively less into each one, with folks who have few kids and invest relatively more time into each being k-strategists)? and those who have most kids tend to be married and marry earlier?

    My view might be colored here by thinking of people who are promiscuous and childless well into their twenties as having a kind of extended adolescence, in other words a slower life history, while people who have got that over with an formed a marriage bond aren’t.

    Africans tend to be seen as having a particularly fast life history, but Cochran has identified their male paternal age as supposedly pretty old across history, and I don’t know that the maternal age is particularly young (don’t know of any datapoints here – menarche in present day Africans is pretty old compared to Westerners, cf Tanner, but this may have been different earlier in history, and doesn’t necessarily line up to having children).

    Reply

  13. hbdchick
    ” think the pacification of europeans (dunno about the others, yet) had several factors including (but maybe not only) these:

    – now your idea that there’s a connection to age at marriage”

    More generally i think the non-pacified have a higher death rate – through above-average boisterousness of all kinds – so unless the physical or cultural environment explicitly compensates for that differential death rate then human populations will naturally pacify over time.

    Reply

    1. @Greying wanderer ” unless the physical or cultural environment explicitly compensates for that differential death rate then human populations will naturally pacify over time.” Alas were it only true. But there is also differential reproduction. If the passive style includes open hearts to non kin, the reproductive penalty will will overwhelm the reduced death rate. Human populations will naturally get more hostile. Relatively new societies like Iceland will for a finite time be passive but when they get old, like Syria or Somalia then things change.

      Reply

  14. @Myself
    “In a marriage culture designed to support slow life history then yes, individuals with a fast life history aren’t likely to build up the resources necessary for late marriage.”

    Except in a welfare underclass environment.

    Reply

  15. HBD Chick,

    You wrote:

    bonus: anonymous conservative has written a lot about r/K selection theory wrt politics — make sure to check out his website!

    I am really interested in this subject and am thinking of buying his book but I wasn’t sure that he actually knows what he was talking about. It seemed to me that he might be mixing up liberals with their clients, the underclass. If liberals are r-selected, why don’t they have lots of kids and neglect them? Still, if you tell me that he does know what he’s talking about re the science I’ll buy it.

    Reply

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