Re: punc eq

H. M. Hubey (hubey@pegasus.montclair.edu)
4 Oct 1995 03:37:48 -0400

Alex Duncan <aduncan@mail.utexas.edu> writes:

>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.

I can certainly understand why the "semantic" disagreements figure
so prominently. In fact, I think you should have used the word
"verbal" instead of semantic. Since the whole "theory" is
verbal, what other kinds of disagreements can arise except verbal.

>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
>reality.

How so?

So it's not "gradual" (whatever gradual means)>

So does this mean that one day some hominid just woke in
in the morning with long legs? Or was the period even
shorter than a single night?

>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.

Suppose the bus schedule on some route goes like this: 80 buses
arrive with about 3 minutes in between them. Only about 4 buses
arrive with waiting time of about 5 hours between them. A man
shows up at a bus stop at random. Will he have a "long" wait
or a "short" wait?

He'll have a long wait.

Because 20 buses will arrive on the average within one hour. So
80 buses will arrive in about 4 hours. The rest of the 20 hours
will only be covered by 4 buses with average wait of aboutg 5
hours.

If big changes are squeezed into a small time interval, there
will be less of those changes, and less of those fossils found.
So then there must have been some great catastrophic change
happening around this time. If not only to hominids then it
must have been happening all over the world. Why didn't all
the other animals start to acquire all these wonderful
properties like beginning to stand up erect, grasp objects
with their paws etc?

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

I suppose the best thing to do is to drop the word altogher,
use fuzzy variable like on a scale of 1 to 10, how gradual
do you mean, or to use a more precise expression for the
word, like the derivative. You can approximate the change in
the length of the bone and then divide by time, and get some
number as to the rate of change and then there's no need to
fight over words like "gradual", "streamlined",....

-- 





				Regards, Mark

				http://www.smns.montclair.edu/~hubey