Re: Are we "special"?
Gerrit Hanenburg (G.Hanenburg@inter.nl.net)
Tue, 03 Dec 1996 17:18:37 GMT
Paul@crowleyp.demon.co.uk (Paul Crowley) wrote:
>Our "specialness" is manifest in the extent of our culture by
>comparison with that of animals, but that may not be a good
>enough for a scientist. We must be be able to show that we are
>"special" in our physiology. This is entirely possible.
Our physiology is basically that of a mammal. If you have studied
human physiology then you know pretty well how mammals function in
general. Physiologically we are not very "special".
>Apparently our central nervous system, including our brain, is
>governed by ~40,000 genes. Each gene is made of about 600
>codons and each codon of 3 bases. That amounts to
>40,000 x 600 x 3 which is 72 million bases.
How did you arrive at the figure of ~40000 genes?
>It is in this area
>that we would differ most from chimpanzees. The major changes
>in morphology, mostly those that concerned bipedalism, would
>have happened quickly. It is in the CNS that selection
>operated over millions of years on millions of mutations to
>produce the distinctive H.s.s. characteristics.
The major differences between human and chimpanzee brains are relative
size and the degree of interconnectivity. These differences can in
principle be the result of differences in developmental timing
(heterochrony) or allometric relationships.These in their turn can be
the result of mutations in only a few (regulatory) genes. The
differences do not require millions of mutations.
The basic organization of the human CNS is not dramatically different
from that of a chimpanzee.