At 08:04 AM 9/28/00 -0500, Jean Edwards wrote:
(snip)
>3. Finally, one of my students was talking with me about the thawing of
>the "ice man" who is estimated to be about 5000 years old. She was
>wondering if his sperm were retrieved and thawed and fertilized with an
>ova, would fertilization be possible and what would the brain be like? I
>told her that to the best of my knowledge, the brain had not changed that
>much in the last 5000 years and that I didn't know how long sperm could be
>frozen.
>
I can't help with the sperm & ova part of the question, but according to
Holloway (1995), the
major evolutionary changes in the reorganization and size of the hominid
brain were:
1) Reduction in Brodmann area 17 (primary visual striate cortex) and
relative increase of
posterior parietal cortex, Brodmann 39. Occurred between 3 and 4 million
years ago
(A. Afarensis)
2) Small increase in brain size, perhaps reflecting only an increase in
overall body size.
Occurred between 2 and 2.5 million years ago (A. Africanus)
3) Reorganization of frontal lobe, mainly involving Broca's area, and
increase in cerebral
asymmetries. Occurred between 1.8 and 2 million years ago (H. Halibus)
4) Modest increase in brain size, probably again proportional to a body
size increase,
as well as an increase in cerebral asymmetries. Occurred between 0.5 and
1.5 million
years ago (H. Erectus).
5) From about 100,000 years ago until about 10,000 years ago, the brain
gradually
increased in size, out of proportion with body size changes, and subtle
refinements
in cortical organization continued.
6) Interestingly, starting about 10,000 years ago there was a small
*reduction* in brain
size, but I cannot tell from the text whether or not this was related to a
change in body
size or not (this may be based on a comparison between Neanderthal and
pre-sapien
brains, but I'm just not sure).
So, with respect to the Ice Man, if he is only about 5,000 years old, it's
unlikely that
his brain was structurally different from ours.
I lifted this information from a chart on page 44 of Holloway's chapter:
Holloway, R.L. (1995). Toward a synthetic theory of human brain evolution.
In J-P
Changeux & J. Chavallon (Eds.), Origins of the Human Brain (pp. 42 - 54).
Oxford
University Press.
Best regards,
Mike
************************************************
Michael J. Kane
Department of Psychology
P.O. Box 26164
University of North Carolina at Greensboro
Greensboro, NC 27402-6164
email: [EMAIL PROTECTED]
phone: 336-256-1022
fax: 336-334-5066
