Lovejoy makes important find on evolution of man

Carol Biliczky

Kent State professor Owen Lovejoy says humans walked upright hundreds of thousands of years before previously thought, smashing beliefs about the famous “Lucy” skeleton.

Lovejoy, a world-renowned anthropologist, said the conclusions come from the recovered remains of a male in the East African country of Ethiopia, “a truly special find in understanding the early evolution of humans.”

The discovery was announced Monday afternoon in the Ethiopian capital of Addis Ababa. The research will be published this week in the Early Online Edition of the Proceedings of the National Academy of Science.

Lovejoy was part of a team led by Yohannes Haile-Selassie, curator and head of physical anthropology at the Cleveland Museum of Natural History, that spent five years extracting skeletal remains from a dig site about 210 miles northeast of Addis Ababa in a desert the semi-nomadic Afar people inhabit.

The international team also included Bruce Latimer, interim director for the Center of Human Origins at Case Western Reserve University in Cleveland; and scientists from the United States, Sweden, France and Ethiopia. Thirty-five to 40 Ethiopians did the excavating.

Starting with a chance discovery of a fragment of a lower arm bone in 2005, the team pulled together remains of the 5-foot-6-inch male they named Kadanuumuu, or “big man” in the local people’s language.

They turned to Kent State’s Lovejoy, a specialist in biomechanics and the anatomy of the lower limbs, for help in interpreting the find.

When Lovejoy reassembled casts of Kadanuumuu’s skeletal remains, he found he was a robust adult who had fractured his ankle as a youth about 3.6 million years ago. More importantly, Kadanuumuu was a member of the Australopithecus afarenesis species, the best-known direct early human ancestor.

His shoulder blade and rib cage are similar to modern humans. His legs were surprisingly long, so he could run and walk at least 400,000 years earlier than previously thought and a million years before the discovery of the first stone tools.

“The skeleton establishes, once and for all, just how ancient upright walking is in our family heritage,” Lovejoy said.

Until now, only one other partial skeleton has been recovered of the same species as Kadanuumuu: the small-brained “Lucy” of 3.2 million years ago.

Lovejoy received international attention when he reconstructed her skeleton in 1974, six years after joining Kent State. At the time, she was the oldest hominid discovered.

It turns out Lucy, recovered just miles from Kadanuumuu, pointed them in the wrong direction.

As she was just 3 feet, 6 inches tall, with short legs and arms that dangled down to just above her knees, researchers previously believed humans of her time were “incompletely adapted to upright walking,” Lovejoy said.

In other words, she both walked and climbed trees.

Now researchers believe she had short legs for a simpler reason: because she was short.

“She was fully adult, but she just happened to be one of the smallest individuals of her species,” Haile-Selassie said.

Lovejoy pointed out that there are tall and short individuals in today’s humans, and Kadanuumuu and Lucy represent different ends of the spectrum from more than 3 million years ago.

Kadanuumuu is the second discovery to be announced in less than a year by the Ethiopian-born Haile-Selassie and Lovejoy.

In October, they were among the scientists to announce the discovery of Ardipithecus ramidus, a newly discovered hominid species that lived 4.4 million years ago in Ethiopia.

“People think that we evolved from apes,” Lovejoy said at the time, “but no, in many ways apes evolved from us.”

Ardi is not a missing link between apes and humans, but pushes human evolution closer to the time 6 million years ago when humans and chimps shared the same ancestor.

The discovery of Ardi was so significant that Science magazine and its publisher, AAAS, named it the 2009 Breakthrough of the Year.

That any skeleton is discovered, albeit fossil fragment by fossil fragment, from these times is astounding, Lovejoy said.

While most bones are trampled, pulverized, crunched by hyenas and obliterated, “Every now and then a body gets strewn about and gets covered by water and deposit and that begins the fossilization process,” he said.

Such is the case with Lucy, Ardi and now Kadanuumuu, giving scientists more fodder as they ponder human origins.

The chances of finding a human skeleton of that age are “astronomically small,” Lovejoy said.

(c) 2007, Chicago Tribune. Distributed by McClatchy-Tribune Information Services.