Re: A layman's question on bipedalism

Robert Scott (
1 Jul 1996 02:28:39 GMT

In article <4qq2l8$> ORDOVER,
>Just picking up the thread of my question again -- is there a reason,
>other than speciecist egotism, that there is a "mystery" of human
>bipedalism but not a "mystery" of avian, dinosauroid, and marsupial
>In other words, I'm not quite getting why the question is "what forces
>made humans bipedal?" instead of "what forces make animals bipedal in
>general?" Why is the specific case considered rather than the general?

I agree absolutely that it is speciecist egoism of the rudest sort to
mystify human bipedalism. True, humans are unique but so are a lot of
deep sea angler-fish and really every other species known and unknown to
man, alien or terrestrial (to speak to the original question). This is
what i think makes biology truly complex and the most difficult of
sciences -- a simple experimental approach doesn't work. Every organism
has a unique history and is as it is because of its evolutionary history.
Natural selection and phylogenetic inertia i am sure have both acted to
bring about modern human bipedalism which is unique. At the same time, a
comparative study of humans and other bipeds may serve to illustrate
critical commonalities (or maybe not).

I would suggest three important points when discussing human bipedalism:

1) vertical posture in a climbing or brachiating ape ancestral ape might
be a critical pre-adaptation for modern bipedalism

2) fossil evidence from australopithecines (curved phalanges is my
favorite) suggest that early ancestral bipeds were also climbers and
engaged in bipedalism different than H. sapiens

3) environmental change (closed to open environmentS? increased
seasonality? habitat fragmentation?) may prove to be an important
selective force leading to bipedalism

All three of these suggest that understanding human bipedalism requires a
historical approach -- documenting human evolution based on *fossil
evidence* (paleontology) which is the only way to resolve many of these
speculative controversies