punc eq

Alex Duncan (aduncan@mail.utexas.edu)
4 Oct 1995 00:50:37 GMT

In article <hubey.812224816@pegasus.montclair.edu> H. M. Hubey,
hubey@pegasus.montclair.edu writes:

>> C) That _you_ cannot envision a series of gradual improvements in
>>bipedal locomotion, in an animal that already _had_ the capability to
>>use it at least some of the time, does not mean that I am so limited.
>>Arguments from ignorance are rarely convincing. That's why they are a
>>logical fallacy.
>If gradual improvements were the norm then that would put
>you in opposition to the latest/greatest addition to evolution,
>that of punctuated equilibrium. Then we'd have lots of fossils
>with legs getting longer and longer, and we need a reason for
>that too.

Once again an argument from ignorance from the AAT folks.
P.E. is by no means accepted by all evolutionary biologists, and, as
Dawkins has pointed out, the differences between supporters of P.E. and
"gradualists" is often pretty semantic.

A change in leg length that may appear to be "gradual" to us due to the
scrappy nature of the fossil record may not have been so at all in

But, finally, the fossil record doesn't seem to show "gradual" change in
hindlimb length. All hominids prior to 1.8 Myr seem to have had
relatively short legs compared to modern humans, and by ~1.8 Myr hominids
w/ "human-length" hindlimbs had appeared, in what seems to have been a
pretty punctual event.

But the change in hindlimb length could very well be argued to be
"gradual" from a slightly different perspective.

Alex Duncan
Dept. of Anthropology
University of Texas at Austin
Austin, TX 78712-1086