Subject: Re: [extropy-chat] re: embedded in open hearts (Meta/EP)

From: Keith Henson <[email-masked]>
Date: Thu, 14 Apr 2005 23:11:57 -0400

At 10:38 AM 14/04/05 +0000, you wrote:
>I find this very interesting:
>
>>We are social primates.  Our genes were selected by millions of years in 
>>hunter gatherer tribes where the people around us usually carried more 
>>copies of our genes than we did.  Thus (by Hamilton's inclusive fitness 
>>criteria) evolution can be expected to have selected genes that give us 
>>psychological traits to take horrible risks and face death to protect 
>>those close to us.
>>
>>(Close companions were almost always relatives in tribal days.   Since 
>>our ancestors didn't have DNA testing, they had to make do with treating 
>>those they grew up with or were friends or bonded with as relatives.)
>
>I think it's highly likely that we would have developed a genetic trait to 
>keep non related companions nearby for reproductive puposes as sex with 
>relatives produces interbred and very unfit children.

That's not the way it works.  Brothers and sisters raised apart are often 
sexually attracted to each other if they meet.

• Shepher (1971) studied young adults who
had been raised on Israeli “kibbutzes”(on
kibbutzes, several unrelated kids are raised
together in small group).
• Found that, out of over 2700 marriages,
none of the couples were raised together
within the same small group...

http://www.psyc.brocku.ca/courses/COURSE%20INFO%202004/freud.2F25.pdf

Sexual attraction is blocked by early exposure.  There are several lines of 
study that support this.

>We can all sense when someone's suitable for reproduction these days (for 
>example) with our sense of smell - I think this would have been the DNA 
>testing organ used in those days.

It seems that female mice can detect different Major Histocompatibility 
Complex (MHC) genes through smell.  They tend to mate (if they have a 
choice) with mice different from them.  It is possible human females have a 
similar ability, but if so, it changes when they are pregnant to preferring 
ones with less difference.  I have not looked for follow ups to the "t 
shirt" experiments done some years ago, so there might be more recent data.

Because tribes exchanged women over extended times, even the swapped in 
women in the tribes tended to be related to the rest of the tribe.

And the men that were either attacking for the tribe or defending tended to 
be brothers, half sibs, first or second cousins.

Which means that selection applied to tribal groups was really genetic 
selection.

Keith Henson

>A fascinating thought!
>
>Jeremy Webb
>
>
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From: "kevinfreels.com" <[email-masked]>
Date: Thu, 14 Apr 2005 23:04:01 -0500

" sex with
> relatives produces interbred and very unfit children. "

Not true at all. This can cause hidden genetic defects to surface more often
because some children are more likelly to be born with two defective copies
of the same bad gene. If sex with relatives created unfit children, we would
very likely not be here. There are many examples of small isolated
populatoins that make it just fine while reproducing with relatives. There's
a very good example of such a group of people in the Middle East in the book
"Mapping Human Histpry" by Steve Olson. I wish I could remember the group,
but right now I have too many other things going on to look it up. As it is,
most Americans can trace just about anyone they know back to about 8th
cousins twice removed.