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Tabitha
Thursday, September 21st, 2006, 11:45 AM
The Times September 21, 2006

Meet the relatives: Little Lucy, the half-ape half-human
By Mark Henderson, Science Editor


THE remains of the earliest known child from humanity’s family tree have been discovered in Ethiopia, filling in a critical missing link in evolution.

The almost complete skeleton belongs to a young girl of the species Australopithecus afarensis — a probable human ancestor that was among the first to walk on two legs — who died at the age of 3 about 3.3 million years ago.

The girl, named “Selam” after the word for peace in several Ethiopian languages, is by far the oldest fossil of a hominin child yet unearthed and blurs the line between apes and humans.

She has also been nicknamed “little Lucy”, after the specimen of the same species discovered just 2½ miles (4km) away in 1974, named Lucy because the scientists who found her were listening to the Beatles song Lucy in the Sky with Diamonds.

Early analysis has already started to transform understanding of a pivotal stage in the evolutionary process that led ultimately to Homo sapiens. Her anatomical features lie squarely in between those of humans and other apes, showing adaptations for walking upright on two legs and for climbing and swinging from trees.

This suggests that the species lived on the cusp of the human family’s transition to a bipedal, ground-based existence, generally accepted as one of the most crucial events in the emergence of the modern anatomy.

Selam’s brain case also suggests that while her intellect was more similar to a chimp than Man, the brain of her species had already started to evolve in the direction that would produce modern human intelligence. Details of the fossil are published today in the journal Nature.

Selam’s leg and foot bones show her to have been already adept at walking upright at the age of 3, showing conclusively that A. afarensis was an accomplished biped.

Her shoulder blades are similar to those of a modern gorilla, while her fingers are long and curved, like those of a chimpanzee. The canals of her inner ear — important for balance — are also quite chimp-like. All this suggests that A. afarensis divided its time between walking upright on the ground, and climbing trees. It is possible that, like modern gorillas, females and infants spent more time in the trees, where they would have been safer from predators.

Another interesting feature is the hyoid or tongue bone, never found before in a species older than Neanderthal man. It influences the voice box and is important to the debate about the origins of human speech. Selam’s hyoid is much more similar to that of modern apes than humans, suggesting that A. afarensis was not capable of language.

Zeresenay Alemseged, an Ethiopian scientist at the Max Planck Institute in Leipzig, Germany, who led the team that found and examined Selam, said she was one of the most important hominin fossils on record: “Her completeness, antiquity and age at death combined, make this find unprecedented in the history of palaeoanthropology, and open many new research avenues to investigate the childhood of early human ancestors.”

The find was also hailed by independent experts, including Donald Johanson, who led the group that found Lucy 32 years ago. “It’s a remarkable and rewarding discovery,” Dr Johanson told The Times. “The completeness is extraordinary, and what is very gratifying for me is that the find was just four kilometres directly south from where Lucy was found all those years ago.”

Selam was found in the Dikika region of northeastern Ethiopia on December 10, 2000, by Tilahun Gebreselassie, a member of Dr Zeresenay’s team. It has since taken the scientists almost six years to extract her remains from sandstone, often using dental tools to remove rock grain by grain.

The entire skull and torso and most of the upper and lower limbs are present. While other juvenile fossils exist, such as the 2.5 million-year-old Taung child of the species Australopithecus africanus, they are known only from fragments of skull, bone or teeth.

Selam’s skull enabled a team from National Geographic to produce an artist’s impression of what the girl might have looked like. “This is something you find once in a lifetime,” Dr Zeresenay said. “Unlike Lucy, the baby has fingers, a foot and a torso. But the most impressive difference between them is that this baby has a face.”

Dr. Solar Wolff
Friday, September 22nd, 2006, 05:07 AM
How can these scientists state that Selam was a female? Usually, the only way to tell is by the angle of the pelvic notch. No pelvis is even mentioned in the disussion of walking. If they had one, it would have been mentioned. But even with the pelvic notch, this angle varies (the degree of opening) from population to population so you really need several to "sex" an individual. Besides all these problems, sexing a child of 3, even with a pelvis, is just a guess at best since nothing is fully formed.

Scholar
Friday, September 22nd, 2006, 05:04 PM
That's a question I was asking myself, and also my friend that saw the story on the news. Wether these scientist have an intricate form of getting sexual identification of ancient australopithecines or they just have a "hunch" I'm not sure. I was reading Origin of Races and I couldn't find any explanations either as to how a australopithicus could be sexed.