The world’s oldest and most complete skeleton of a potential human ancestor — named “Ardi,” short for Ardipithecus ramidus — has been unveiled by an international team of 47 researchers.Their unprecedented, 17-year investigation of Ardi is detailed in a special issue of the journalScience.
Researchers have unveiled the oldest known skeleton of a putative human ancestor–and it is full of surprises. Although the creature, named Ardipithecus ramidus, had a brain and body the size of a chimpanzee, it did not knuckle-walk or swing through the trees like an ape. Instead, “Ardi” walked upright, with a big, stiff foot and short, wide pelvis, researchers report in Science. “We thought Lucy was the find of the century,” says paleoanthropologist Andrew Hill of Yale University, referring to the famous 3.2-million-year-old skeleton that revolutionized thinking about human origins. “But in retrospect, it was not.”
A multinational team discovered the first parts of theAr. ramidus skeleton in 1994 in Aramis, Ethiopia. At 4.4 million years old, Ardi is not the oldest fossil proposed as an early hominin, or member of the human family, but it is by far the most complete–including most of the skull and jaw bones, as well as the extremely rare pelvis, hands, and feet. These parts reveal that Ardi had an intermediate form of upright walking, a hallmark of hominins, according to the authors of 11 papers that describe Ardi and at least 35 other individuals of her species. But Ardi still must have spent a lot of time in the trees, the team reports, because she had an opposable big toe. That means she was probably grasping branches and climbing carefully to reach food, to sleep in nests, and to escape predators.
Most researchers, who have waited 15 years for the publication of this description and analysis, agree that Ardi is indeed an early hominin.