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Little Girl, 3 Million Years Old, Offers New Hints on Evolution

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Little Girl, 3 Million Years Old, Offers New Hints on Evolution


Published: September 21, 2006

If the fossil Lucy, the most famous woman from out of the deep human past, had a child, it might have looked a lot like the bundle of skull and bones uncovered by scientists digging in the badlands of Ethiopia.

The paleontologists who are announcing the discovery in the journal Nature today said the 3.3-million-year-old fossils were of the earliest well-preserved child ever found in the human lineage. It was estimated to be about 3 years old at death, probably female and a member of the Australopithecus afarensis species, the same as Lucy’s.

An analysis of the skeleton revealed evidence of a species in transition, the scientists said in interviews yesterday.

The lower limbs supported earlier findings that afarensis walked upright, like modern humans. But gorillalike arms and shoulders suggested that it possibly retained an ancestral ability to climb and swing through the trees.

“Her completeness, antiquity and age at death make this find unprecedented in the history of paleoanthropology,” said Zeresenay Alemseged, the Ethiopian leader of the discovery team and a researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

Two reports of the findings are being published in Nature. The National Geographic Society, a supporter of the research, will run a popular article on the fossil child in the November issue of its magazine.

At a news conference in Addis Ababa, Ethiopia, the scientists gave the fossil the name Selam, which means peace in Ethiopia’s official Amharic language.

Scientists not involved in the research said the fossils were a significant find that should provide new insights about the afarensis species and a little-known period of early human origins.

“The child really confirms that afarensis was walking upright,” said Tim D. White, a paleoanthropologist at the University of California, Berkeley. “It has the potential to answer old questions and raises some new ones” — including their behavior in trees. Dr. White, who has found even earlier human ancestors in Ethiopia, participated in the analysis of the 3.2-million-year-old Lucy fossils. They were uncovered not far away in Ethiopia in 1974 by Donald C. Johanson, who is now director of the Institute of Human Origins at Arizona State University.

Other discoveries show that the afarensis species, a major branch of the human family tree, lived in Africa from earlier than 3.7 million to 3 million years ago.

In an accompanying commentary in the journal, Bernard Wood of George Washington University, who had no part in the discovery, said the specimen was “a veritable mine of information about a crucial stage in human evolutionary history.”

Dr. Wood, a paleoanthropologist, also noted how rare it was for the fragile bones of infants to survive long enough to fossilize. “But if they do, they provide precious evidence about the growth and development of the individual and the species,” he wrote.

Until now, Dr. Wood said, the earliest comparably complete specimen of a human-related child was that of a Neanderthal who lived less than 300,000 years ago in Syria.

The discovery team said the largely intact condition of the fossils indicated that the child was presumably buried in sand and rocks shortly after death during a flood in a desert region known today as Dikika, in northeastern Ethiopia.

Then, in December 2000, along came a team of fossil hunters led by Dr. Alemseged. On a steep hillside, one of the men, Tilahun Gebreselassie of the Ethiopia Ministry of Culture and Tourism, was the first to see the child’s tiny face looking up from a block of sandstone. It was a long and projecting face with a flat nose.

The face and skull were clearly that of a young afarensis, the scientists concluded almost immediately.

Dr. Alemseged’s team spent much of the last five years extracting the rest of the specimen from the surrounding stone with dentist’s drills and picks. The tedious work exposed the full cranium and jaws, the torso and spinal column, limbs and the left foot. The child’s one complete finger was curled in a tiny grasp, much like a young chimpanzee’s. The skeleton is much more complete than Lucy’s.

Although the fossils are still being studied, Dr. Alemseged and his colleagues noted several important findings and areas for further research. The Dikika girl’s brain size, for example, was about the same as that of a similarly aged chimpanzee, but a comparison with adult afarensis skulls indicates a relatively slow brain growth slightly closer to that of humans.

The presence of a hyoid bone was a surprise. It is a rarely preserved bone in the larynx, or voice box, that supports muscles of the throat and tongue. The bone in the infant appeared to be primitive and more similar to those found in apes than in humans, the scientists said, but is the first hyoid found in such an early human-related species and thus important in research about the origins of human speech.

The first relatively complete shoulder blades to be found in an australopithecine individual was one of the most puzzling aspects of the discovery, several scientists said. The lower body appeared to be adapted for upright walking by afarensis. But the shoulders and long arms were more apelike.

In the journal report, Dr. Alemseged and his team wrote that “the functional interpretation of these features is highly debated, with some arguing that the upper limb features are nonfunctional retentions from a common ancestor only, whereas others proposed that they were preserved because A. afarensis maintained, to some degree, an arboreal component in its locomotor repertoire.”

NYT Science

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