Re: EVOLUTION: The Aquatic Ape

Jay Reynolds Freeman (
Fri, 24 Jan 1997 12:36:33 -0800

> I don't think it did, i.e., brains stayed much the same for a million
> years or more after Lucy (I think).

Later _Australopithecus_ species had larger brains. I am not
sure we have enough data to say anything about brain-size trends
in _A_afarensis_.

> There are some *real* problems in growing larger brains, ask any
> woman who has had a baby.

Indeed! At birth, the head of a human infant is in essence an
interference fit in the birth canal -- which is not true for any
mammal outside the hominid line. Childbirth is sort of a *yawn*
experience in most other mammals, most often resembling what happens
when you squeeze a watermellon seed between thumb and forefinger. The
price that humans pay for it seems to indicate that our large brain
has high survival value.
I have heard it seriously suggested that one almost universal
characteristic of the hominid line is "obligate midwivery"; survival
of mother and child at birth is made far more likely by the presence
of competent adult assistance. Not that women cannot give birth
unassisted, just that it is vastly more likely that their genes will
be removed from the pool if they try. Thus one can make a parallel
case -- I don't say a completely convincing one -- that we are
obligate social beings, who require (in the sense of natural
selection) a cooperative society at least as large as an extended
family or perhaps a small band. (Hmn, that line of reasoning might
not be popular among extropians, but what's a squirrel for if not to
chatter obnoxiously and hurl nuts...)
Odd bit of whimsy, that the "oldest profession" may have been
(And incidentally, the use of the specific term, "midwife", was not
intended to suggest anything about midwife gender.)

> I don't have a pointer, but I remember that one chimp was taught to
> chip rock--or at least fracture them to get a sharp edge. I suspect
> that our hands are not that advanced over a chimp's.

Our hands can take what is known as a "precision grip" -- the way
most people hold a screwdriver -- as well as a "power grip" -- the way
most people hold a hammer. The former is much rarer among creatures
with hands, than the latter. I believe I recall that Chimpanzees have
the latter, but not the former.
At least one Chimpanzee has indeed been taught to fracture rocks to
get a sharp edge, and has found use for said edges in his habitat.
Chimp use of shaped stone in the wild has been reported, though not in
quite the sense that most people would immediately take it --
somewhere in Africa there is a flat rock that has been used by Chimps
as an anvil for cracking nuts, for long enough to have been deformed
by repeated blows of (I think) the hammer stone. It is in effect a
"Chimpanzee midden", by analogy with California Indian sites where
stone has similarly been deformed into mortar-like depressions.

> > I agree with that, I just have my doubts that a pre-human throwing a rock
> > would even be a good bluff, and as a offensive hunting weapon I think it
> > would be hopeless.
> It might be more useful for that in the early stages, but after a while of
> using rocks/sticks to fend off preditors, some genious of Lucy's clan
> would use it to obtain lunch. After that . . . .

I believe I remember that object-hurling by other primates has been
observed to serve as a predator deterrant in the wild, and also occurs
as part of various kinds of intra-species display. Indeed, though, once
developed for any purpose, it might find others.

> In fact, it has just occured to me that an animal who ventured out on the
> flats, even to scavenge, would no longer have the option of going up a tree
> to avoid preditors.


-- Jay Freeman, First Extropian Squirrel