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ant and dec
 
Posts: n/a
Default Would you like to be eaten?

S. Maizlich wrote:
> ant and dec wrote:
>
>> pearl wrote:
>>
>>> "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
>>>

>>
>>
>> Thanks again.
>>
>> I have moved my position on whether meat had a major part to play in
>> human evolution. I will read more, but on balance there seems little
>> evidence to support that it did.

>
> It is UNDISPUTED by evolutionary biologists that meat played an
> indispensable role in human evolution. Meat's role was both direct and
> indirect. The direct role was in providing the massive amount of
> protein needed for brain development. The indirect role is as an
> organizing principle of human activity.


I need to investigate more. The reference above seems to give a strong
case for a "visual specialization" evolution and it states that "no
consensus has emerged", but I'm happy learn and admit my ignorance on
brain evolution theories.