There is considerable argument about whether the Dikika girl
could also climb trees like an ape.
This climbing ability would require anatomical equipment like
long arms, and the "Lucy" species had arms that dangled down to just
above the knees. It also had gorilla-like shoulder blades which
suggest it could have been skilled at swinging through trees.
But the question is whether such features indicate climbing
ability or are just "evolutionary baggage".
The Dikika girl had an estimated brain size of 330 cubic
centimetres when she died, which is not very different from that of
a similarly aged chimpanzee. However, when compared to the adult
afarensis values, it forms 63 - 88% of the adult brain size.
This is lower than that of an adult chimp, where by the age of
three, over 90% of the brain is formed. This relatively slow brain
growth in the Dikika girl appears to be slightly closer to that of
Slow, gradual development in an extended childhood is regarded
as a very human trait - probably to enable our higher functions to
Professor Fred Spoor of University College London said the find
would give scientists a "detailed insight into how our distant
relatives grew up and behaved... at a time of human evolution when
they looked a good deal more like bipedal chimpanzees than like us."
Dr Jonathan Wynn of the University of St Andrews, UK, and
colleagues at the University of South Florida dated the sediments
surrounding the remains and came up with an age of 3.3 million
The "Lucy" skeleton, discovered in Hadar, Ethiopia, in 1974
belongs to the same species as the Dikika girl. For more than 20
years it was the oldest human ancestor known to science.