It's a girl -- she's 3.3 million years old, almost human / Fossils of oldest known child hominid found in Ethiopia 'in mint condition',
Keay Davidson, Chronicle Science Writer
Published 4:00 am, Thursday, September 21, 2006
Scientists have uncovered fossils of the oldest known hominid child near the site in Ethiopia where researchers discovered prehistory's most famous female -- Lucy, a 3.2 million-year-old skeleton -- in 1974.
The unnamed tot's remains appear to be those of a 3-year-old female that lived 3.3 million years ago and, like Lucy, is a primitive human ancestor of the species Australopithecus afarensis. It probably walked upright, but it might also have been able to climb trees, judging by its curved finger bones, a research team reported in today's issue of Nature.
"It would have resembled a chimpanzee more than it would have a modern human, although it's clearly neither of those things," Bernard Wood, an anthropologist at George Washington University in Washington, said in an interview.
"I think it would have had a hairy body, but who's to know? Nobody knows the answer to that," added Wood, who wasn't connected with the discovery, but wrote an accompanying essay about it for Nature.
The cause of the child's death remains unknown. Judging by the terrain and geological strata in which it was found, scientists say the youngster's body was likely quickly covered by floodwaters.
The unusually well-preserved remains were found partly buried in the solidified sediments of a river channel in Dikika, Ethiopia, in 2000.
Like a family genealogical chart with many different branches, sub-branches, and twigs, Australopithecus afarensis is one early species within a group of mammals known as hominids, which over millions of years have evolved into modern humans. Scientists still debate whether "A. afarensis," as they call the species, is a direct ancestor of modern humans or was an evolutionary "twig" that eventually went extinct.
The scientists know the child was female "because she has small canines (teeth)," said team leader Zeresenay Alemseged of Leipzig, Germany, in an e-mail. "She is the oldest and most complete" known specimen of a hominid child.
Wood agreed. "It's in mint condition, (although) some (parts) are missing that may well turn up later. This is a discovery of an incredibly well-preserved individual ... that lived between 3 and 4 million years ago," he said.
After the find, Alemseged quietly spent the next six years carefully scraping away the sediments and analyzing the creature's fossils.
The discovery delighted Donald C. Johanson, the paleoanthropologist who stunned the world when he found the 3.2 million-year-old Lucy fossil at Hadar, Ethiopia, a few miles from the Dikika site. "I don't think there's any question that (the child is) the same species as Lucy," because its features "are identical to what we see in all of the Hadar hominids," Johanson said in a phone interview Tuesday.
Scientists have previously found fragments of a few other Australopithecus afarensis children, "but nothing as significant as this," Johanson said. The new find is "much more complete," with a skull containing "a virtually complete set of teeth," plus "parts of legs and arms and thorax, and two very thin shoulder blades."
A leading paleoanthropologist, Tim White of UC Berkeley, called the find an "important new fossil that confirms a lot (of ideas) already inferred for A. afarensis from other fossils found earlier. (It's) hard to find youngsters like this," he said in an e-mail. "Other children of this and related species ... were known before this, but none so complete."
Nature whimsically referred to the child in a press release as "Lucy's baby." However, White cautioned that the child couldn't literally be Lucy's baby because it is hundreds of thousands of years older than her.
It took a village to raise that child: Since Johanson's historic discovery of Lucy, researchers have uncovered the remains of some 400 other Australopithecus afarensis at sites in Ethiopia and Kenya.
Johanson recalled how in 1974, he and colleagues looked for fossils at the Hadar site. His girlfriend had joined him on the expedition, and after finding the Lucy fossil, "that evening we were listening to a Beatles tape of 'Lucy in the Sky with Diamonds.' " His girlfriend said, "If you think it's a female, why don't you name it Lucy?"
"The name stuck," said Johanson, who left Berkeley in 1997 to run the Institute of Human Origins in Tempe, Ariz., where Alemseged spent three years as a postdoctoral researcher.
Just as there's no known explanation for the child's death, "we still don't know exactly why Lucy died," Johanson noted. "There's one puncture mark in her pelvis. Maybe a crocodile dragged her into the river."
After hearing of Alemseged's discovery, Johanson added, "somebody jokingly said to me: 'How does it feel to be a grandfather?' "