On Fri, 4 May 2001 11:32:57 -0500, Philip Thrift <[log in to unmask]>
wrote:

I wrote:
>>Was it the increased front lobe what made the big leap possible?
>
>Maybe better hunters (throwing accuracy at a distance). Remember the
>throwing theory:
>
>    http://williamcalvin.com/1990s/1993Unitary.htm
>

You have a good link collection.
Looking at the picture with the throwing angle (and the rabbit)
reminded me that the exact timing for the usage of the hand of a piano
player is only possible as a cascade of many brain cells are working
together.
This may be the same reason as the exact timing necessary to achieve
marksmanship when throwing something.
I don't know if the hundreds of neurons necessary to time such a precision
movement are related to the 14 billions of brain cells.
That's a 100 million fold - while smaller creatures (like
Australopithecines) had just 1/3 of the brain - but still enough volume
to 1/3 of 14, say 4 billion brain cells. (?)
Ok, that's a possible reason - at least a benefit of brain enlargement.

.. of the brain zone that directs the arms and fingers.
Which is located at the upper mid of the head (right and left).
It could be included in the one enlargement indicated at the upper brain -
Humans have a round upper skull, where it was flat in neanderthals.
Of course you'd prefer to use the fingers for throwing rocks at rabbits-
ok why not.

The *front* lobe is something different.
It has no easy associated function, but it's typical human.
In fact a high forehead is somewhat attractive.
Maybe it's for socializing, maybe for our ability to "think ahead".
I vote for the latter.
The "big leap" (of Jared Diamond) occured as late as 40000 bc.
Which very many inventions. And the displacement of the neanderthals.

Regards,

Amadeus

btw.. you mentioned the brain enlargement of hominids in the course of a
discussion about basic paleonutrition.
You don't hope to gain further brain enlargements by a particular diet,
do you? (that's ;-)