Palaeontology (1)

Elaine Morgan (
Wed, 02 Aug 1995 14:55:44 GMT


I have ordered from the British Library all seventeen of the refs.
recommended by Alex Duncan. Six have arrived. The following are just
preliminary observations.

It has long seemed strange to me that the same facts can be so
differently interpreted by people as intelligent as we all agree Alex
(for instance ) is, and as I believe I am. (Don't take a vote on it)
Increasingly I suspect we are making different assumptions about the
timing and sequence of events.

Look at these two statements in a paper by Susman, Stern, and Jungers
(from : "Ancestors : the hard evidence.")

(1) "In the wild, chimpanzees also spend a substantial portion of their
time on the ground, as quadrupeds, but their manner of quadrupedalism
is more costly than that of almost any other ground-dwelling
quadruped. Compromise to increase the range of their habitat seems to
be the best explanation for this apparently stable adaptation in

(2) "Bipedalism may have been a response to the need to travel to and
among the ever shrinking forested areas."

They seem to be saying: "The chimpanzee became quadrupedal because it
needed to increase its range. The hominid became bipedal because it
needed to increase its range."

That is a perfectly tenable position, but only on the premise that the
animals were aleady very different before either of them set a foot on
the ground - eg maybe the prehominid ape was smaller-bodied, had a
different intramembral index, etc. But this is pure speculations,
isn't it? For all we know, at 4mybp all the African apes were
small-bodied and resembled one another very closely. It has been
suggested that the l.c.a. looked like a bonobo. The gorilla could have
become larger much later - as late as 2mybp or even 1mybp. We have no

If they did resemble one another closely, we would need a very good
reason why one lot would respond to the advent of savannah mosaic by
becoming quadrupedal and the other by becoming bipedal.

There is also an unwarranted assumption that the trend towards
bipedalism postdated and was a consequence of the opening up of the
forests and the advent of s/mosaic. That too is pure speculation,
isn't it? Susman et al make a point of stressing that bipedalism did
not arrive overnight. : "Far from being abrupt and complete, its
evolution can be seen as having taken place over a considerable time
span". I'll drink to that, If in the beginning they spent say 90% of
their time in the trees and only occasional intervals locomoting at
ground level (whether across grass or through water) it could have
evolved very slowly indeed. It could have been under way, gradually,
since the onset of speciation. It could have been a response to the
same ecological event that caused the speciation. That would be

I'll come to Laetoli and all that jazz when more papers arrive.