[Taxacom] chimp-human interbreeding & fuzzy origins?

John Grehan jgrehan at sciencebuff.org
Mon May 22 14:21:15 CDT 2006

I'll make a stab at answering in part the questions about characters in
chimps and humans although I got a bit lost with the relative apomorphic
plesiomorphic states.

According to Andrews (1987) and Andrews and Martin (1987) humans and
chimpanzees share only four uniquely shared characters. Of these none
appear to be valid. Shoshani et al (1996) said there were seven uniquely
shared characters. None of these appear to be valid (and one author has
even agreed with this for two characters). Begun et al (1997) said there
were four uniquely shared features for chimpanzees and Australopithecus
afarensis. All are undocumented and the author has been unable to
provide corroborating documented. Begun (1999) proposed seven
synapomorphies for humans and chimpanzees of which three are invalid,
and four are undocumented (and therefore untestable at this time). By
comparison humans share at least 42 proposed synapomorphies with
orangutans (Schwartz 1987, 1988, 2005), and of these at least 28 are
well documented and apparently robust.

OK - how good is this data? Fairly good in that I reviewed the evidence
for every single proposed character in a referred [yes indeed] paper
that will be coming out in July in the Anatomical Record B: New

John Grehan

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