Humans and apes

[john Grehan]

Thomas Lammers wrote

>Having spent nine years in a museum setting and interacted frequently with
>exhibit developers and outreach educators, I think I understand John's
>viewpoint.  It seems to me that what he wants to do primarily is to give
>visitors a glimpse of Science As Process, and that The Origins of Humans
>is, in many ways, a secondary message.

That is certainly a major part of it. However, I do admit I have a current
bias towards the orangutan hypothesis. It was my personal reaction to the
hypothesis that it made coherent sense out of a number of hominid
characteristics that were otherwise problematic - such basic and rather
prominent uniquely shared 'human' characteristics such as thick dental
enamel, a well developed beard and mustache in the male, the absence of an
estrous cycle, most axillary position of mammary glands, longest hair
length, absence of anogenital tumescence during the menstrual cycle, and
the longest gestation period scaled to body weight.

These rather prominent characteristics may otherwise seem to 'human' and
yet there they are uniquely shared with orangutans, not the African apes
(thick dental enamel does occur in one New World and one Old World monkey
so that character is contingent upon accepting that similarity as an
independent convergence). This certainly piqued my curiosity given the
otherwise overwhelming impression that the African ape connection is
unproblematic.

I now find that much of the justification for the African ape relationship
is based in large part on the presumption that molecular characters have
automatic precedence over morphological ones. There are certainly
morphological studies also supporting the African connection. In some cases
it appears that supposedly uniquely shared characters turn out to also
occur in other apes or monkeys. For others I am still in the process of
looking into what characters are being used (and my thanks to those
suggesting some recent publications).

Of course the orangutan relationship removes the vexing question of
evolving bipedalism from from a specialized quadrupedal knuckle-walking
ancestor (or proposing that knuckle-walking evolved twice if chimps are our
nearest relatives).

Some of these 'cladistic' characters seem rather obscure or minute compared
to those listed above. In one cladogram the origin of thick dental enamel
would have evolved and been lost about three times on the way to humans. So
its an interesting subject to look into (doubly so when one reads hints in
the fossil literature that appear to complain that the earliest fossil
hominds are not looking as much like chimps as one would expect).

>WAY too many folk think of science as A Body of Knowledge or as An
>Attitude, and *not* as a Process for Understanding.  Presenting them with
>contrasting hypotheses and laying out the ways by which scientists
>evaluate these hypotheses is, I think, an excellent idea.  As long as the
>accompanying text is honest about the data and its interpretation, I think
>this is exactly the way to proceed.  More power to the good folks in Buffalo!

I appreciate the compliment

John Grehan

Dr. John Grehan
Director of Science and Collections
Buffalo Museum of Science
1020 Humboldt Parkway
Buffalo, New York 14211-1293
Voice 716-896-5200 x372
Fax 716-897-6723
jgrehan at sciencebuff.org