'Lucy's baby' found in Ethiopia

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The juvenile specimen is wonderfully preserved

 

 

Skull Revealed

The 3.3-million-year-old fossilised remains of a human-like child

have been unearthed in Ethiopia's Dikika region.

The female Australopithecus afarensis bones are from the same species

as an adult skeleton found in 1974 which was nicknamed " Lucy " .

 

Scientists are thrilled with the find, reported in the journal

Nature.

 

They believe the near-complete remains offer a remarkable opportunity

to study growth and development in an important extinct human

ancestor.

 

The juvenile Australopithecus afarensis remains vanishingly rare.

 

The skeleton was first identified in 2000, locked inside a block of

sandstone. It has taken five years of painstaking work to free the

bones.

 

" The Dikika fossil is now revealing many secrets about

Australopithecus afarensis and other early hominins, because the

fossil evidence was not there, " said dig leader Zeresenay Alemseged,

of the Max Planck Institute for Evolutionary Anthropology in Leipzig,

Germany.

 

Delicate bones

 

The find consists of the whole skull, the entire torso and important

parts of the upper and lower limbs. CT scans reveal unerupted teeth

still in the jaw, a detail that makes scientists think the individual

may have been about three years old when she died.

 

 

This puts afarensis in a special position to play a pivotal role in

the story of what we are and where we come from

 

Zeresenay Alemseged, Max Planck Institute

Remarkably, some quite delicate bones not normally preserved in the

fossilisation process are also present, such as the hyoid, or tongue,

bone. The hyoid bone reflects how the voice box is built and perhaps

what sounds a species can produce.

 

Judging by how well it was preserved, the skeleton may have come from

a body that was quickly buried by sediment in a flood, the

researchers said.

 

" In my opinion, afarensis is a very good transitional species for

what was before four million years ago and what came after three

million years, " Dr Alemseged told BBC science correspondent Pallab

Ghosh.

 

" [The species had] a mixture of ape-like and human-like features.

This puts afarensis in a special position to play a pivotal role in

the story of what we are and where we come from. "

 

Climbing ability

 

This early ancestor possessed primitive teeth and a small brain but

it stood upright and walked on two feet.

 

There is considerable argument about whether the Dikika girl could

also climb trees like an ape.

 

 

The lower limbs show the Dikika girl could walk upright

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 humans.

 

Slow, gradual development in an extended childhood is regarded as a

very human trait - probably to enable our higher functions to

develop.

 

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 years.

 

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.