Crush on a third cousin:
In response to the article I will cite below I did a web search and found a lively discussion of whether it is all right to marry a third cousin.  Of course it is more than all right if your interest is in having children.  Alas, when I sought to get into the debate I found that the particular part of the site had gone silent.  But it was heartwarming to see how the vast majority of people offering an opinion said, “Go for it.”  However the site – – seems to be up and running and I am giving it a try. 

The article (Lundström et al. Biological Basis of the Third-Cousin Crush  SCIENCE vol. 320 no. 5880 May 30, 2010 page 1160-1161) notes the results of the study of Iceland genealogies by Helgason et al. and explains that the mechanism whereby  nearer kin couples are more fertile is already probably known. It turns out to be based on something called the major histocompatibility complex.  The term arose when people were trying to work out what animals had tissues that were compatible in transplant into other animals.  However it has also been shown to be important in mating choice, presumably because of similar smells of people with differences in their histocompatibility complexes.

At hazard of being impudent, I recall something from the marriage ceremony in which it is mentioned that the husband and wife are supposed to be of “one flesh.”  Maybe that means they are supposed to smell alike, since it is quite clear that they need to be related if the tribe is to survive in the long run

The article points out that it was suggested all the way back in 1978, before even I was aware of the idea, that mating selection was governed by a tendency to balance kin versus strange, and this was confirmed with experiments on birds, which turned out to prefer first or second cousins to siblings and unrelated birds.  Another experiment cited in the article established that histocompatiblity complexes, inherited on the paternal not the maternal side, affect mate selection through scent. 

Well knock me down with a feather.  I would have sworn it went through the maternal side.  No matter.  It all seems to have fallen into place.

There is a less than agreeable little story I was told as a child.  A man went to see an execution by the greatest executioner in the land.  The poor wretch of a prisoner was forced to kneel.  The executioner came out and swung his sword a couple of times and then left.  The man noticed that the crowd was watching intently.  He asked a man beside him, “What’s going on?”

“Shh.   Wait ‘til he shakes his head.”

There needs to be a bit of head shaking.

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