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).


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!)


linkfest – 10/29/12

a day late. sorry! sometimes sh*t just happens. (~_^)

Ethnic disparities in breast cancer survival remain despite socioeconomic similarities“All-cause survival was worse for African-Americans and better for Latinas and Asian-Americans compared with non-Latina whites after adjusting for age, study and tumor characteristics. When the researchers additionally adjusted for treatment and reproductive and lifestyle factors, they found that African-Americans had similar survival rates to non-Latina whites, but the survival rates of Latinas and Asian-Americans remained better.”

Diversity may be fatal, says new government health study“[P]eople suffer less cancer and heart disease when they live among their racial or ethnic peers.” – via mangan’s.

If Smart Is the Norm, Stupidity Gets More Interesting“Human intelligence varies.” – you don’t say?! (it’s in the nyt, believe it or not!)

Do Intelligent People Drink More Alcohol? – yes. yes, we do. (*hic*)

A detour through Europe?“The lithic technology of southwestern France (c. 22,000-17,000 BP) strangely resembles that of the first paleo-Amerindians (c. 12,000). Some people speculate that early Europeans reached North America by crossing the Atlantic. The truth is even more incredible. Early Europeans spread eastward and became the ancestors not only of the Amerindians but also of East Asians.” – from peter frost.

Secular change in the B/W IQ gap (in the US) – from chuck. see also steve sailer.

Penis size and infant mortality – from the autistic nerdling epigone.

Placebo effect may be ‘down to genes’“Those with a particular version of the COMT gene saw an improvement in their health after placebo acupuncture.”

The Evolution of Female Bisexuality – from jayman.

Pitch Perfect: It’s All In The Genes” – maybe/prolly. see also you, too, can have perfect pitch!

Hispanic Bio-Diversity: A Primer – from nelson.

Smoking causes asthma in second generation offspring – epigenetic effects in rats.

Epigenetic inheritance is a wild goose chase“Epigenetics matters, but not between generations.”

Appearance-based politics: Sex-typed facial cues communicate political party affiliation – republican women more feminine looking than democrat women.

Men better multi-taskers than women: study

Who Would Win in a Fight: a Modern Human or a Neanderthal?“We beat them at evolution. But what about fisticuffs?”

The Island Where People Forget to Die“[P]eople on Ikaria were, in fact, reaching the age of 90 at two and a half times the rate Americans do. (Ikarian men in particular are nearly four times as likely as their American counterparts to reach 90, often in better health.) But more than that, they were also living about 8 to 10 years longer before succumbing to cancers and cardiovascular disease, and they suffered less depression and about a quarter the rate of dementia.”

bonus: More Intelligent Birds (Like More Intelligent Humans) Have Evolutionarily Novel Preferences

bonus bonus: Electric Bugs: New Microbe Forms Living, Deep-Sea Power Cables

bonus bonus bonus: New study sheds light on how and when vision evolved“Opsins, the light-sensitive proteins key to vision, may have evolved earlier and undergone fewer genetic changes than previously believed….”

(note: comments do not require an email. intelligent bird.)