Re: A Point for Calvin

Arnold Doray (
Thu, 03 Oct 1996 22:50:36 -0700

Stephen Barnard wrote:
> wrote:
> >
> > Thomas Clarke wrote:
> > > Apparently 11 to 14 year old boys can kill bears with rocks.
> > >
> > > I think William Calvin hypothesized that it was throwing
> > > ability that provided the selective advantage for large
> > > brain size in hominds. Perhaps this event is a point for him.
> >
> > Perhaps the significant fact is that a group of boys working together
> > killed a bear by throwing rocks. A lone boy throwing stones would have
> > probably been mauled, eliminating the possibility of his genes surviving.
> Just for the record, this was a very,very small bear.
Okay, I suppose I was over doing things a little, but I did not know the size
of the bear. In any case, my first observation would still apply : It is the
ability to work in groups that provided the selective advantage for large
brain size in hominds.

The throwing ability is fairly simple to achieve. Robot arms with redundant
degrees freedom have been made to achieve good throwing ability via simple
neural-nets, like the Kohonen self-organizing map. Archer fish ( a species of
small fish which 'spit' their above-water prey down ) employ a rudimentary
throwing technique yet their brain size / body ratio is similar to that of
teleosts which do not employ such techniques but occupy similar niches.

I'll throw in a little something for discussion : why then do lions ( which
are social, and hunt in packs ) have similar brain size / body ratios to
tigers which are generally solitary ? There is a species of hawk ( I've
forgotten the name ) which live in Arizona which also show well developed
social structure and hunt in groups (!)Why do these have bs/b ratios like the
garden-variety hawk ? So, perhaps social behaviour does not necessitate large
brainsize / body ratios !

Perhaps it's the ability to *deceive* that really matters (when it comes to
providing the selective advantage for large brain size), and that this can
only be fully developed with some social structure ?

Comments are welcome.

Arnold Doray
(Disclaimer : These opinions are mine,mine, all mine ! )