There's an interesting evolutionary psychology paper in the new Nature. It's by Tooby and Cosmides, and it investigates the roots of the incest taboo. The researchers found that, on average, our repulsion at the idea of having sex with a sibling correlates with two variables: how long we lived with that sibling and how long we watched our mother care for that sibling (their "perinatal association"). We use these two variables to compute a "kinship index" that "corresponds to an estimate of genetic relatedness between self and other." Siblings with a high "kinship index" not only triggered the incest taboo - the idea of having sex with them is disgusting - but exhibited increased altruistic behavior. That's a nice proof of kin selection.
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David Burbridge continues his awesome series of posts on the history of evolutionary genetic thought with
Siblings of those diagnosed with autism are more than 20 times as likely a
What psychological phenomenon do you believe in but cannot prove? I'd have to go with birth order. Having grown up with three siblings, I can't help but be convinced that my birth order (I'm the second oldest) has had a profoundly important influence on my personality.
This is a guest post by Christy Tucker, one of Greta's top student writers from Spring of 2007.
I recall reading somewhere, not that long ago, someone who pointed out that dynastic marriages (in China, I think it was) which involved bringing a very young child to live in the equally young spouse's household until they grew up and were formally married often failed to produce offspring because the spouses regarding each other as kin, even though they weren't.
Ridger: That was the Westermarck(sp?) study, it was mentioned in at least the SciAm article on this.