I recently mentioned the genetic advantages of discouraging cousin marriage, which the Roman Catholic Church tried to do everywhere but mostly only succeeded in northern Europe. I focused then on the longer-term selection of developing traits for determining whether to trust strangers or not and developing attractiveness skills for business, mating, and safety. I had not known that James Thompson had reported in 2014 on research showing just how much impact cousin marriage has on IQ in the next generation. He linked to it today in the West Hunter thread that just went up about inter-caste mating in India, Wedding Planners.
It's grim.
I skimmed it, and didn't see where the information about the parent generation came in. Maybe causality works the other direction as well for 1st cousin marriage? If you aren't a prize, you're stuck with cousins...
ReplyDeletejames, it was tough to find because the text seemed to focus on standard deviation but I think it was in the first table. Average IQ for offspring of first cousin marriages dropped to about 70 from 86 if I read it right. The text didn't explain it explicitly.
ReplyDeleteFocus on the 4th and 5th paragraphs. I don't think his is talking about parent vs child but averages from the same generation with different parental relationships.
ReplyDeleteI suspect that cousin marriage is more likely in small groups where there are very few non-cousins
ReplyDeleteIf the parent generation of the 1st cousin marriages is also from 1st cousin marriages, and shares the low iq, do they have low-iq children because they are inbred, or are they inbred because they're low-iq with poor prospects outside the family?
ReplyDeleteThe statistics aren't great, but the double first cousin numbers sound like there was a really low outlier in there. That'd drag down the average and up the rms. And maybe double firsts have higher rates of those rare outliers.
Ah. I followed the link at the top of the page, where he shows their plots. Nope, not outliers.
ReplyDeleteI imagine if it goes on long enough, nearly everyone available is genetically equivalent to a third cousin, even if they technically aren't.
ReplyDeleteThompson points out in the case of some groups, simply going over to another jati might yield a 36-point IQ increase. Seems impossible.