WASHINGTON – A nearly 13 million-year-old ape discovered in Spain is the last probable common ancestor to all living humans and great apes, a research team says in Friday's issue of Science magazine.
A husband-and-wife team of fossil sleuths unearthed an animal with a body like an ape, fingers like a chimp and the upright posture of humans. The ancient ape bridges the gap between earlier, primitive animals and later, modern creatures.
This newest ape species, Pierolapithecus catalaunicus (search), is so significant that it adds a new page to ancient human history.
The researchers sidestepped a controversy raging through the field by not claiming their find moves great ape evolution — and the emergence of humans — from Africa to Europe. Salvador Moya-Sola (search), one of the Science paper co-authors, said the new ape species probably lived in both places.
"The problem is the fossil record," Moya-Sola said. "The fossil record in Africa, especially in the upper Miocene, is very scarce. And the fossils are very rare. But this is only a question of work, and work, and work."
David Begun, a University of Toronto researcher who studies fossil evidence of human and ape evolution, said the Spanish find bolsters the idea that modern apes evolved primarily in Eurasia.
"There is no evidence in Africa, so you can always speculate they might have been there," Begun said. "I prefer to go with the evidence."
Coaxed by a reporter to say Pierolapithecus catalaunicus represented a "missing link," Meike Kohler (search), another of the paper's co-authors, demurred. "I don't like, very much, to use this word."
Kohler added: "This does not mean that just this individual — or even this species, exactly this species — must have been the species that gave rise to everything else which came later in the great ape tree. But it is, if not the species, most probably a very closely related species that gave rise to it."
Maybe. Maybe not, argues David Strait, an assistant professor of anthropology at the University at Albany who studies early humans. He said the specimen is "spectacular," but he worried the team's approach to assigning evolutionary relationships was a bit informal and needs confirmation by more rigorous methods.
"'Ancestor' is a loaded term. It's very hard to identify ancestors in the fossil record," Strait cautioned.
The site near Barcelona that yielded the specimen had only one hominid, or ape-like primate. Moya-Sola said apes, however, were common in the area millions of years ago. The team has already found a tooth elsewhere and expects to find more hominid fossils.
Still, scientists who puzzle through the mysteries of early human history were electrified by the Pierolapithecus catalaunicus discovery.
"This is a remarkable find," said F. Clark Howell, a University of California at Berkeley (search) professor emeritus. "It indicates a diversity in hominids ... in western Eurasia at a time where we're beginning to think we had a good handle on how much diversity there was."
Howell helps run a National Science Foundation (search) initiative that examines hominid origins.
Living great apes include humans, chimps, gorillas and orangutans. The group is thought to have split from the lesser apes, such as gibbons and siamangs, about 14 million to 16 million years ago.
Paleontologists have searched for remains of great ape ancestors after that key split. Fossils have been scarce and hypotheses floated on the basis of bone fragments.
The team led by Moya-Sola and Kohler pieced together 83 bones and identifiable fragments of bones from an adult male ape.
This ape didn't swing through trees with the curved fingers of an orangutan. Nor did it knuckle-walk on four limbs with the horizontal trunk posture of a chimp.
The ape's body design suggests it was an adept and agile climber that kept its trunk upright. To do that, its chest had to be shaped in a certain way and the shoulder blades needed to hold to a certain position on the back.
"Our fossil shows this," Moya-Sola said.
What it does not show is the evolution of hands suited to the demands of such locomotion as swinging through tree branches. That fine-tuning of great ape hands, the team argues, came later.