the tree by the river (
29 Sep 1995 12:49:58 -0600

In article <44feng$> Alex Duncan <> writes:
>In article <> H. M. Hubey,
> writes:
>In most quadripeds the the bend at the knees is in the opposite direction
>from humans; and the primates seem to be already close to human. What
>could have caused this change?

Most? Can you give me an example? (While I make no claim to be an
expert on vertebrate anatomy, I can't think of any tetrapods whose
knees bend the other way--even other bipeds (birds, for example) have
knees that bend the same way ours do. I can come up with a few
arthropod examples, but I don't see that as a major stumbling block
for evolution.)

> If we look at slowly changing from one
>angle (most animals) to primates, somewhere in the middle of evolution
>the whole leg would have to rotate 180 degrees and have the legs face
>outwards or inwards, practically making the animals lame. Is this
>explained by any theory, other than one that begs for catastrophic
>changes (i.e. punctuated equilibrium) without really explaining anything.
>Maybe they didn't need their legs at all during this time.

You wouldn't be comparing human knees to the ankles of non-human
tetrapods, would you? If so, I'm going to have to hit you with a
rolled-up newspaper.

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