The skull of the 3.3-million-year-old girl

New Delhi, Sept. 20: Scientists exploring a hillside in Ethiopia have announced the discovery of a 3.3-million-year-old near-complete skeleton of a three-year-old girl, the oldest juvenile remains of one of the earliest direct ancestors of humans.

In a report that will appear in the journal Nature tomorrow, an international team of scientists has said features on the skeleton provide clear evidence for bipedal walking as well as the capacity for climbing trees.

The scientists, who recovered the skeleton piece by piece over a four-year period from Dikika in Ethiopia’s Hadar region, have described it as the earliest and most complete skeleton of a juvenile human ancestor ever found.

They have classified the skeleton as Australopithecus afarensis, a species that lived between 3 million and 3.9 million years ago and is believed to have walked upright.

Scientists had unearthed the first Australopithecus afarensis fossil — a female who was named Lucy — in the same region of Ethiopia in 1974. The child lived about 150,000 years before Lucy.

“Her completeness, antiquity and age of death combined make this find unprecedented in the history of paleoanthropology,” said Zeresenay Alemseged, the director of the Dikika Research Project who is now at the Max Planck Institute for Evolutionary Anthropology. The skeleton will provide new avenues to investigate the childhood of early human ancestors, he said.

Australopithecus afarensis is widely believed to be an early direct ancestor of the group of species called Homo that includes Homo sapiens, or modern humans.

The skeletal remains include the entire skull with a natural sandstone impression of the brain, as well as the entire torso and parts of the upper and lower limbs — parts of shoulders, spinal column, ribs, right arm, fingers, legs and left foot.

Complete skeletons of children have hitherto been found only from recent members of the human evolutionary tree such as Neandarthals or modern humans. Earlier remains have been scanty — nothing more than some teeth or a piece of jaw or skull. “We now have for the first time hard evidence for a clear picture of what early child human ancestors looked like,” Alemseged said.

A CT scan allowed scientists to examine teeth and determine the sex and age of the skeleton. Scientists detected the first remains in December 2000 and picked up the rest of the skeleton over the next four years.

The research team — including scientists from France, Germany, the UK and the US — analysed the skeleton and found that the lower body is adapted to upright movement. However, the shoulder blades exhibited gorilla-like features, triggering speculations about what was the preferred mode of movement for this species — walking upright like humans or tree-climbing like apes.

“I don’t think a three-year-old adapted to bipedality is going to spend much time climbing trees, but the mix of features in this skeleton is going to stir up the debate about locomotion in early Australopithecus,” said William Kimbel, a team member from the Institute of Human Origins at the Arizona State University.

Researchers expect the new find to provide insight into growth and development of Australopithecus afarensis since the child’s remains could be compared with the remains of Lucy, a complete adult female skeleton.