Mon, 14 Aug 95 12:25:50 -0500

NE>You say "Humans have children that are less developed than our
NE>relatives because our brains are so much bigger than our closest
NE>relatives", but the actual fact is quite different, to whit:
NE>"Humans can have brains are so much bigger than our closest relatives
NE>because our have children are born less developed than our relatives".

NE>You see, the difference in wording is fairly subtle, but the
NE>difference in meaning is enormous. Your wording says the cause
NE>of the change is something that the change itself allows; this
NE>would mean that the cause is something from the future, which you
NE>can easily see is impossible.

NE>Jim Moore (j#d#.moore@canrem.com)

Let me see if I can state this the way I understand, albeit not in
technical language:

The female in the group with the slightly larger head and the slightly
larger brain is presumably slightly more intelligent and thus more
successful in rearing offspring, and she passes those genetic traits on
to her numerous daughters and granddaughters, and to her male progeny
also. The problem is that the greatgranddaughters have a problem
birthing the babies with the increasingly bigger heads. The female in
that generation with the slightly larger and more flexible pelvis will
be more successful, as will the female who tends to deliver just
slightly more premature or immature infants (but has the intelligence to
care for them well). So there are (at least) three tendencies
cooperating in this particular process of natural selection, and the
female with the tendency for the best combination of all three will be
the most successful in producing and rearing viable progeny. Larger
brain cases, wider and more flexible pelvic girdles, and immature
infants all advance together as evolutionary trends.

Does this make sense to y'all?


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