Scientists: 'Ardi' Fossil Sheds Light on Origin of Human Species

Ardi lived 4.4 million years ago in the woodlands of East Africa. She spent most of her time in the trees. She stood about four feet tall, weighed 110 pounds, and had long arms, short legs, and a grasping big toe that was perfect for clambering branch to branch. She ate in the trees, raised her offspring in the trees, slept in the trees.

But sometimes she came down to the ground, and stood upright. She could walk on two legs. She was, in a sense, taking baby steps on a journey that would change the world.

"Ardi" is the nickname given to a remarkable, shattered skeleton that an international team of scientists believes is a major breakthrough in the study of human origins. The skeletal remains were painstakingly recovered from the Ethiopian desert along with bones from at least 35 other members of a species scientists call Ardipithecus ramidus. The 15-year investigation of Ardipithecus culminated Thursday in the publication of a raft of papers in the online edition of the journal Science, as well as dual press conferences in Washington and Addis Ababa, Ethiopia.