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The New Face of Evolution Volume 60 Number 1, January/February 2007
by Zach Zorich

Did our early ancestors walk or climb their way to becoming human?

In a field that typically deals in spans of a million years or more, celebrity can seem especially fleeting. So maybe it was time for the 3.2-million-year-old Australopithecus afarensis known to the world as "Lucy" to step aside as paleoanthropology's reigning diva, an unofficial title she has held since her 1974 discovery when she stunned the world by providing the first solid evidence that humans had evolved from apelike ancestors. Now Lucy is being upstaged by a younger, more complete fossilized superstar: an afarensis skeleton named for the Ethiopian word "peace"--Selam.

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Zeresenay Alemseged compares a newly discovered piece of the 3.3-million-year-old Australopithecine child named Selam to an older specimen at the National Museum of Ethiopia in Addis Ababa. (Courtesy Max Planck Institute) [LARGER IMAGE]

"We have captured a moment in the life history of this individual," says paleontologist Zeresenay Alemseged of the Max Planck Institute in Leipzig, Germany, "but also a moment in the history of the species Australopithecus afarensis." That moment was frozen by a flood that swept down Ethiopia's Awash River 3.3 million years ago, sealing the bodies of several mammal species in the flood-borne sediment. Zeresenay led the team that discovered the child's remains. His analysis shows Selam was only three years old when she died, presumably from drowning in the flood. Her bones show no signs of trauma, being gnawed by scavengers, or abraded by river sediments, indicating she probably had flesh on her bones when the river sealed her off from the world.

Selam's remains are far more complete than two other Australopithecine children found in fossil beds at Laetoli in Ethiopia and Taung in South Africa. In addition to revealing how afarensis children developed physically, she is giving scientists some new anatomy to obsess over, namely her face, shoulder blades, even the hyoid--a fragile bone from her throat.

"Afarensis was, in a way, a bipedal primitive ancestor." says Zeresenay. "A primitive skull with a small brain, and many primitive features on the upper skeleton were sitting on a more humanlike lower skeleton." Understanding how afarensis evolved from the last common ancestor we shared with the chimpanzee will provide a unique window into how the world of 3 million years ago shaped the ancestors of the human race.

Zach Zorich is associate editor at ARCHAEOLOGY.

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© 2007 by the Archaeological Institute of America
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