Re: Brain Development

Ralph L Holloway (rlh2@COLUMBIA.EDU)
Thu, 2 Feb 1995 23:51:54 -0500

With all due respect to Calvin's ideas, most of human evolution during
the "Ice Age" took place in Africa where there was no Ice Age, and the 4X
enlargement can be found right there in that continent... R. Holloway.
Thu, 2 Feb 1995 wrote:

> >What made other less intelligent hominid species less advantageous and ultimate
> >ly extinct?
> An interesting theory I heard is that homo sapiens killed them off through
> warfare.
> On brain development in general; I believe that intelligence is one of those
> traits that is selected for in many species. Dumb species don't hang around
> for very long.
> Also, William Calvin has an interesting theory he puts forth in _The Ascent of
> Mind_ that claims human brain expansion is the result of the Ice Age. It seems
> that during the last 2.5 my the brain of homo sapiens sapiens increased by 4X.
> Calvin thinks this is the result of adaptation to the changing environment. The
> continual abatement and advance of the ice sheets (with no less than 18 cycles
> during this period) acted as a motor for encephalization. Ice would advance,
> creating harsh conditions that required intelligence to cope with, and then
> recede creating a rich, abundant environment that spurred fairly rapid bouts of
> speciation. After several million years of this,voila! I at least think is a
> more credible theory than the "direct energy from the intestines to the brain"
> theory from homos starting to eat meat that was posted a few days ago.
> Regards,
> james b.