"ant and dec" > wrote in message ...
> pearl wrote:
<..>
>
> Thanks for that. Very interesting; of particular personal interest was
> the anthropological articles on calcium and osteoporosis.

You're welcome.

> :-)
>
>
>
> The theory I was thinking of was the "brain food theory":
>
>
> Brain food
>
> Because meat is rich in calories and nutrients, easy-to-digest food,
> early Homo lost the need for big intestines like apes and earlier
> hominids had. This freed up energy for use by other organs. This surplus
> of energy seems to have been diverted to one organ in particular - the
> brain. But scavenging meat from under the noses of big cats is a risky
> business, so good scavengers needed to be smart. At this stage in our
> evolution, a big brain was associated with greater intellect. Big brains
> require lots of energy to operate: the human brain uses 20% of the
> body's total energy production. But the massive calorific hit provided
> by meat kick-started an increase in the brain size of early humans.
>
> http://www.bbc.co.uk/sn/prehistoric_...thought1.shtml

If that were the case, carnivores should have massive brains!

> Mind you, this was written by Robert Winston who's has sold himself to
> the food industry.
>
> http://politics.guardian.co.uk/lords...560223,00.html
> http://www.omega3.co.uk/omega3/pages/omega_3.php



Proc Biol Sci. 1998 Oct 22;265(1409):1933-7.
Visual specialization and brain evolution in primates.
Barton RA.
Department of Anthropology, University of Durham, UK.

Several theories have been proposed to explain the evolution of
species differences in brain size, but no consensus has emerged.
One unresolved question is whether brain size differences are a
result of neural specializations or of biological constraints
affecting the whole brain. Here I show that, among primates,
brain size variation is associated with visual specialization.
Primates with large brains for their body size have relatively
expanded visual brain areas, including the primary visual cortex
and lateral geniculate nucleus. Within the visual system, it is, in
particular, one functionally specialized pathway upon which
selection has acted: evolutionary changes in the number of
neurons in parvocellular, but not magnocellular, layers of the
lateral geniculate nucleus are correlated with changes in both
brain size and ecological variables (diet and social group size).
Given the known functions of the parvocellular pathway, these
results suggest that the relatively large brains of frugivorous
species are products of selection on the ability to perceive
and select fruits using specific visual cues such as colour.
The separate correlation between group size and visual brain
evolution, on the other hand, may indicate the visual basis of
social information processing in the primate brain.

PMID: 9821360 [PubMed - indexed for MEDLINE]
http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Abstract