Re: naked bipeds

Phil Nicholls (
Fri, 27 Oct 1995 18:21:22 GMT (H. M. Hubey) graced us with the following

> (Phil Nicholls) writes:

[Nearly every species has one or two unique adaptations. In the case]
>>of Homo sapiens you are being very selective. IF we have learned
>>anything about human evolution it is that everything does not happen
>>at once. We know, for example, that bipedalism occurs before
>>expansion of brain size or tool use.

>Unless this is a typo I assume that you are now generalizing
>to a higher degree of abstraction. Maybe you are saying something
>like "If we examine the fossils and living animals (on all planets
>on which life has evolved)we'll find that bipedalism had occurred
>before expansion of brain size." If this is so, then we'd have to
>account for other animals which have large brains and which are
>not bipedal (again I'm using brain_mass/body_mass). I don't have
>the figures handy but how does Lucy compare in this aspect to
>say a dolphin or whale?

No. When I wrote that bipedalism occurs before the expansion of the
brain I was referring to changes within the hominid lineage. This
was clearly indicated in the two sentences the precede this statement.
Unfortunately you deleted that one line (I put it make to illustrate
my point).

>>Hairlessness could have occurred
>>only within the last 40,000 years for all we know.

>It could have occurred at any time. But I've been led to
>believe that the advantages of hairlessness in expelling
>heat from the body was a major factor in what we are since
>we are larger(!) and need this to expel heat whereas small
>animals like chimps don't need to lose hair. Then it would
>seem that the hair loss should have occurred together with
>the hominids increasing in size, or could have occurred around
>the time of Lucy is the world wide temperature was getting hotter.

Lucy's stature is estimated at about 106cm, which puts here in the
same ballpark as chimpanzees, gorillas and orangutans. Wheeler has
proposed that bipedalism and the resultant increase in heat rejection
capacity was facilitated by the reduction of body hair.

Both of Wheeler's statements can be tested but we do not know nor will
we ever know if they are the reason for the evolution of bipedalism in
hominids. This is one of the limitations of science when it comes to
events that have occurred in the past. We can be rather confident
about processes and propose probably explanations based on available
evidence and that is pretty much it.

The problem with the AAH is that it is not constructed on evidence,
but rather on the basis of very selective morphological similarity
between some aquatic mammals and modern humans.

Phil Nicholls
"To ask a question you must first know most of the answer"
-Robert Sheckley