Selecting for intelligence
<p>Mike Smith relays an interesting possible explanation for the observed<br />
statistical fact that American and European Jews have a mean IQ a<br />
standard deviation higher than Caucasian gentiles:</p>
<blockquote><p>
During the period from ancient times to modern times, there was a<br />
constant phenomenon of Jews converting to Christianity (there were<br />
many social pressures to do so). In a nutshell, the idea is that the<br />
lower-IQ Jews were statistically more likely to convert, as it freed<br />
them from having to learn to read Torah. During the Middle Ages, it<br />
was not worth the effort for most people to become literate; the<br />
payback was not worth it. Books were rare and expensive, and learning<br />
to read was no guarantee of getting ahead in life. Of course, people<br />
like to do what they&#8217;re especially good at, and the higher-IQ&#8217;s among<br />
the Jews did not find learning to read to be such a burden. As such,<br />
they were statistically less likely to convert (and statistically more<br />
likely to become fathers of many children in a culture that valued<br />
intelligence.) It is worth noting that in ancient times, Jews were not<br />
stereotyped as especially intelligent; that stereotype arose in the<br />
Middle Ages.
</p></blockquote>
<p>This is a special case of one of my favorite Damned Ideas, originally<br />
developed by John W. Campbell in the 1960s from some speculations<br />
by a forgotten French anthropologist. Campbell proposed that the<br />
manhood initiation rituals found in many primitive tribes are a<br />
selective machine designed to permit adulthood and reproduction only<br />
to those who can demonstrate verbal fluency and the ability to override<br />
instinctive fears on verbal command.</p>
<p>Campbell suggests that all living humans are descended from groups<br />
of hominids that, having evolved full-human mental capability in some<br />
of their members, found the overhead of supporting the dullards too<br />
high.  So they began selecting for traits correlated with intelligence<br />
through initiation rituals timed for just as their offspring were<br />
achieving reproductive capacity; losers got driven out, or possibly<br />
killed and eaten.</p>
<p>Campbell pointed out that the common elements of tribal initiations<br />
are (a) scarring or cicatricing of the skin, opening the way for<br />
lethal infections, (b) alteration or mutilation of the genitals,<br />
threatening the ability to reproduce, and (b) alteration of the mouth<br />
and teeth, threatening the ability to eat.  These seem particularly<br />
well optimized for inducing maximum instinctive fear in the subject<br />
while actually being relatively safe under controlled and relatively<br />
hygenic conditions.  The core test of initiation is this: can the<br />
subject conquer fear and submit to the initiation on the basis<br />
of learned (verbal, in preliterate societies) command?</p>
<p>Campbell noticed the first order effect was to shift the mean of<br />
the IQ bell curve upwards over generations.  The second-order effect,<br />
which if he noticed he didn&#8217;t talk about, was to start an arms race in<br />
initiation rituals; competing bands experimented with different<br />
selective filters (not consciously but through random variation).<br />
Setting the bar too low or too high would create a bad tradeoff<br />
between IQ selectivity and maintaining raw reproductive capacity.  So<br />
we&#8217;re descended from the hominids who found the right tradeoff to push<br />
their mean IQ up as rapidly as possible and outcompeted the groups<br />
that chose less well.</p>
<p>It doesn&#8217;t seem to have occurred to Campbell or his sources, but<br />
this theory explains why initiation rituals for girls are a rare and<br />
usually post-literate phenomenon.  Male reproductive capacity is<br />
cheap; a healthy young man can impregnate several young women a day,<br />
and healthy young men are instinct-wired to do exactly that whenever<br />
they can get away with it.  <em>Female</em> reproductive capacity, on<br />
the other hand, is scarce and precious.  So it makes sense to select<br />
the boys ruthlessly and give the girls a pass.  Of course if you push<br />
this too far you don&#8217;t get enough hunters and fighters, but the right<br />
tradeoff pretty clearly is not 1-to-1.</p>
<p>(This would also explain why humans are designed for mild polygyny,<br />
1 to 3 sexual partners per male.  You can spot this by looking at<br />
where human beings are on various physical characteristics that<br />
correlate with degree of polygyny in other primates &#8212; disparity in<br />
average size between males and females, for example, is strongly<br />
correlated with it.)</p>
<p>What Campbell <em>did</em> notice is that this theory of selection<br />
by initiation would neatly explain one of the mysteries of human<br />
paleoanthropology &mdash; how human beings got so smart so fast.  The<br />
differences between H. Erectus and H. Sapiens are not large in<br />
absolute genetic terms (they can&#8217;t be, we share over 94% of our genome<br />
with chimps) but they&#8217;re hard to credit given normal rates of<br />
morphological change in mammals and only two million years to work<br />
in.  <em>Something</em> must have been putting hominids under<br />
abnormally strong selective pressure &mdash; and Campbell&#8217;s idea<br />
is that we did it to ourselves!</p>
<p>Now, I&#8217;m not sure I believe Jews bootstrapping themselves up a<br />
whole standard deviation in less than 2000 years, but if you apply<br />
a similar idea to a longer timeframe it begins to look pretty<br />
reasonable.  (And Campbell did suggest that the Jewish practice of<br />
infant circumcision had originally been a manhood rite.)</p>
<p>Within my lifetime, I expect we&#8217;re going to have the ability to do<br />
germ-line enhancement of human intelligence.  I strongly suspect that that<br />
will set off another arms race &mdash; because cultures that suppress<br />
that technology will be once again doomed against cultures that do.  And<br />
this time, we&#8217;re smart enough to know that in advance&#8230;</p>
