martedì 26 aprile 2011

"Lucy's Baby" found in Ethiopia

Riporto questo interessante articolo che ho letto sul ritrovamento dello scheletro di una bambina appartenente alla stessa specie di Lucy, il famoso esemplare di femmina adulta di "Australopitecus Afarensis" ritrovato molti anni prima.

The 3.3-million-year-old fossilised remains of a human-like child have been unearthed in Ethiopia's Didika 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 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. 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.
This early ancestor possessed primitive teeth and a small brain but it stood upright and must have walked on two feet. 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 swimming through trees.
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 slightlycloser 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 wuold 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 humans. Dr Jonathan Wynn of 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.

Allo scheletro fossile della giovane femmina di circa 3 anni, ritrovata nel 2000, è stato dato il nome di Selam che in amarico significa "pace".
Su Wikipedia ho trovato l'immagine del cranio di Selam.

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