Nearly complete skull of 'son of Lucy' found

Nearly complete skull of 'son of Lucy' found

By Lidia Wasowicz

BERKELEY, California (UPI): Researchers reported unearthing the first nearly complete skull of one of man's oldest ancestors last week, in a finding that may finally unveil the face of "Lucy," the celebrated skeletal remains of the earliest known ancestor of modern man.

Painstakingly pieced together from more than 200 rock- encrusted fragments, the fragile three-million-year-old skull found in a barren area called Hadar in the Araf region of northeastern Ethiopia bears an ape-like jutting jaw, thick, protruding ridges above the eyes and a small brain case.

The 1992 discovery offers by far the clearest look yet at the brain size, face shape, jaw structure and teeth of Australopithecus afarensis, the most ancient human ancestor, the researchers told a news conference.

Sieving loose soil in fine screens and hand-picking through gravel-sized flakes of bone, the scientists made their find on a hillside near a dry river bed, only a mile from where Lucy's remarkably intact but nearly headless skeletal remains were unearthed in 1974.

The skull, of a male 180,000 years younger and substantially larger than Lucy, the most famous example of the species, was recovered by William Kimbel and Donald Johanson of the Institute of Human Origins in Berkeley, Calif., and Yoel Rak of Tel Aviv University in Israel.

Noting the earliest sample of the species dates back 3.9 million years, the scientists said their discovery suggests the small-brained, upright-walking A. afarensis flourished in eastern Africa for nearly a million years.

Great branching

"There is no obvious sign of evolution in this prehuman species for about a million years," said Kimbel, director of paleoanthropology at the Berkeley institute. "Yet later, within only a fraction of that time, it gave rise to a great branching of the family tree."

The explosion of new species sometime after 3 million years ago included the larger-brained, tool-using lineage that led directly to humans.

Although the largest of any species of Australopithecus, the skull represents afarensis because of its ape-like structure compared to that of other prehuman species, the scientists said in their report published in the British journal Nature.

They disagree with other researchers who believe the present collection of A. afarensis constitutes an assortment from two or more quite different species.

The three discoverers maintain that all of the 3-to-4-million- year-old ape-like fossils found in the Afar region represent one species -- the root of the human family tree -- with males considerably larger than females, as is the case with some of today's great apes.

Other scientists, however, find the size variation and other differences too great for a single species and theorize the larger-boned fossils come from an extinct, so-called "robust" species that lived at the same time as a smaller species, represented by Lucy, which started the Homo lineage.

This group thinks that by three million years ago, the two distinct lines had already diverged. Kimbel, Johanson and Rak believe the divergence of primitive upright-walking hominids -- humans and their extinct ancestors and relatives -- into discrete lineages occurred later.

"With the afarensis anatomy apparently static for almost a million years, we are eager to find fossils from the next few hundred thousand years when the species apparently gave rise to several hominid lines," Kimbel said.

"We want to find out what happened shortly after the time of Lucy's species," Johanson said.

"It would be nice to see who is in charge of the tools that were made just a few hundred thousand years after this skull was buried," Rak said. "This would be a fantastic gap to bridge."

The expeditions were funded by the National Science Foundation, the National Geographic Society, the L.S.B. Leakey Foundation and Lufthansa German Airlines.