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I spent an afternoon this week getting a personal tour of a cast
of the skeleton of Ardipithecus from Tim White, the leader of the
team that decsribed it. Call me a nerd, but I found it
spine-tingling to hold in my hands the skull of a 4.4.million year
old creature that might be very close to my own ancestor.
But it was the details that stole the show. The lack of
sharpening on the rear of the canines (unlike a chimpanzee), the
flared pelvis of a regular biped, the curved but relative short
metatarsals of the foot, the hints of very little sexual
The ecology, too, is intriguing. The Afar depression was not
such a depression then, and the weather was sufficiently damp for a
fairly rich forest to be growing there, albeit with patches of
grassland. By far the commonest antelopes were woodland-dwelling,
browsing kudu. Ardi herself ate fruits and nuts from trees, not
grasses -- this can be decided by isotopic analysis -- and she was
a good climber as well as a walker. Her molar teeth had not grown
robust like those of Lucy, for grinding grass seeds and roots, but
nor had they shrunk for processing soft fruit as those of modern
Nobody quite knows where it fits in the family tree. White
reckons it post-dates the split with chimpanzees and lies on our line, because it had features
shared with human beings that chimps lack -- it was a good biped
Ar. ramidus indicates that
despite the genetic similarities of living humans and chimpanzees,
the ancestor we last shared probably differed substantially from
any extant African ape. Hominids and extant African apes have each
become highly specialized through very different evolutionary
Others argue it might pre-date the split, on the
grounds that the molecular clock points to a divergence at around
3-5 million years ago. This disagreement has already grown quite testy,
though I cannot really see why: it just seems to be the pattern in
academia at the moment.
White has also been sharply criticised by primatologists, some
of whom hate his conclusion that chimpanzees have done a lot of
evolving since the split -- or to put it another way, that in
certain features the last common ancestor resembled us more than it
resembled chimps. This -- to me obvious -- point upsets them
because they think it undermines their claim that studying and
conserving chimpanzees is justified as a study of what our
ancestors must have been like.
That's weird. Study chimps to find out what a modern ape does,
not as a form of self-obsession. Conserve it because it is rare,
beautiful and fascinating, not out of narcissism.
Ardipithecus is a wonderful glimpse of the past. It's somewhere
pretty close to the missing link, and it's interesting in its own