> I certainly see a use for bipedalism on the savannah, just look at
> meerkats. On flat plains with high grass, the higher you can stand, the
> earlier you get a warning of predators. Additionally, the ability to
> throw rocks and spears with decent power over decent distance also
> mandates an upright, high stance with a hip structure that also is
> conducive to bipedalism over quadupedalism. Those who could throw the
> spear the hardest and furthest got the best meat, and therefore were the
> alpha males that got to reproduce.
How about just chucking rocks to ward off *other* scavengers?
In addition to the proper body structure, using spears also requires time,
energy and brains to make them. Even if early hominids were smart enough
to make spears, it would not make sense to expend the needed resources
unless their brains could do the calculations you describe below in order
to make enough kills to pay for the investment in fashioning a weapon.
I've not read much about scavenger hypotheses, but the follwing scenario
could serve as an evolutionary bootstrapping event to make the advance
from scavenger to hunter. Killing an animal with a
projectile requires considerable skill because the hit must be forceful
and direct, but to scare an animal you only need to get close. I can
see a band of hominids with raw rocks and sticks laying claim to a more
skilled hunters prey. Once in a while, one or a few good hits while
repelling a carnivor or other scavengers would result in a kill. The
benefit of killing ones own meal instead of waiting for someone to do it
for you have already been stated. Once the brain was wired for accurate
throwing, time invested in more deadly projectiles would pay off.
Also, the scavenging scenario could explain selction for group cohesion.
Note that many scavengers as well as hunters of the African plains feed
in groups. I can't think of a good estimate of how many 3-4 feet tall
bipeds could shoo a self respecting savanah dining party, but they would
definatly need a plan and communication system, however crude.
IMO, what I've said falls right in line with the rest of your post.
Exovivo!
Michael Bowling
>
> This is a fine example of technology effecting evolution. Due to the
> computational demands of intuitive trajectory calculation, and the
> communication demands of hunting in teams or packs, lager brain cases
> were seen as an evolutionary advantage. WHile the analytical abilities
> of hunting were amplified in males, the females who had to look after
> offspring had to coordinate defenses against predators whil the males
> were hunting, so they developed better communication skills.
>
> Want to prove this is so? Try to teach a chimp to throw a 90 mph
> fastball on a major league field in the strikezone. It'll never happen.
> He doesn't have the hips for the job.
> --
> TANSTAAFL!!!
>
> Michael Lorrey
> ------------------------------------------------------------
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> #!/usr/local/bin/perl-0777---export-a-crypto-system-sig-RC4-3-lines-PERL
> @k=unpack('C*',pack('H*',shift));for(@t=@s=0..255){$y=($k[$_%@k]+$s[$x=$_
> ]+$y)%256;&S}$x=$y=0;for(unpack('C*',<>)){$x++;$y=($s[$x%=256]+$y)%256;
> &S;print pack(C,$_^=$s[($s[$x]+$s[$y])%256])}sub S{@s[$x,$y]=@s[$y,$x]}
>