SubscribeIf you measure enough things about enough couples, the answer that finally emerges is unexpectedly simple: on the average, spouses resemble each other slightly but significantly in almost every physical feature. That goes not only for the traits you'd think of first, like skin and eye and hair color, but also for an astonishing variety of other traits, such as thickness of lips, breadth of nose, length of ear lobe and middle finger, circumference of wrist, distance between eyes, and lung volume. Experimenters have made this finding for people as diverse as Poles in Poland, Americans in Michigan, and Africans in Chad.This is because we share a lot of genes with our families and both with humans and animals, women seem to seek out traits associated with dad and bro, and boys traits associated with mom and sis. Diamond discusses several animal experiments such as mice whose mother's vaginas were sprayed with lemon juice grew up to prefer female mice with lemon-sprayed vaginas.
Moderate inbreeding may also produce biological benefits. Contrary to lore, cousin marriages may do even better than ordinary marriages by the standard Darwinian measure of success, which is reproduction. A 1960 study of first-cousin marriages in 19th-century England done by C. D. Darlington, a geneticist at Oxford University, found that inbred couples produced twice as many great-grandchildren as did their outbred counterparts.The article also notes that 80% of marriages in history have been between second cousins and closer. The flip side to that instinct to assortive mate, is the danger or recessive genes that can lead to all sort of nasty diseases (which is why we tend to see more recessive gene disorders in more inbred populations; thus Ashkenazi Jews appear to have more crazy disorders, than say, the French, and the Amish appear to be the most fucked of all). So we have some additional psychological mechanisms to keep these other psychological mechanisms in check. I'll just quote my comment from several years ago on the Westermark incest avoidance mechanism:
Hidalgo your alternative theory (not accepted today) was actually first formulated by Sigmund Freud. Frued concluded that our earliest sexual feelings were for our family (particularly our mothers), and that, as you say, we develop incest taboos as an unconscious method to suppress these latent urges. Westermark, on the other hand, said almost the opposite, that the incestuous urges never develop. What method did he propose for this?
Imprinting.
The scientist Konrad Lorenz (1937) discovered that newly-hatched chicks would follow the first colorful moving object that they encountered, regarding it as their mother (realized after Mr. Lorenz himself unwittingly became the mother of some baby geese). They mentally 'imprint' that object as their mother, with a pre-programmed set of rules regarding it (follow, imitate, etc.). Imprinting had to occur within the first 25 hours of hatched brain development; and the sooner the more reliably it was imprinted This mother identification is known as 'filial imprinting', but the birds also avoided mating with their siblings by a similar mechanism of 'sexual imprinting.' Like the fake mother, those avoided as mates don't necessarily have to be genuine siblings, just anything 'imprinted' as a sibling, which it will be if it shares the correct combination of sibling-like traits (proximity, motion, etc..) As troutfishing said, all this 'sexual imprinting' is for avoiding the harmful effects of inbreeding.
Westermark then proposed a 'sexual imprinting' model for humans, that has received much support through the years. To name some good evidence: A) Unrelated children raised together in communal Israeli kibbutzim, seldomly pair bond as adults, despite a lack of discouragement to do so. And B) In Taiwanese arranged marriages, the female is raised together with her future husband. Looking at data from over 14,000 of these, Anthropologist Arthur Wolf compared fertility and divorce rates from these marriages to traditional arranged marriage cultures, and decided there was a significant amount of greater dissatisfaction.
What's even more, it appears not only that children 'imprint' their siblings and parents, but that grown adults 'imprint' children as well. Looking at evidence from sexual abuse (no links, damn.) , it can be seen that the more removed from a child's infancy a step-parent enters into the family unit, the more increased the likelihood of eventual sexual abuse. This is not only true for step-parents, but for actual parents as well, who may be missing from a child's earliest years for whatever reason, and later return.
So, it's definitely out there somewhere. You may want to look at some porno video websites to see how many titles they have, which ought to give you an idea of how common/popular it is.
posted by cell divide at 4:37 PM on February 6, 2006