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Long-Awaited Research on a 4.4-Million-Year-Old Hominid Sheds New Light on Last Common Ancestor

Fifteen years in the making, a dossier of papers on "Ardi" published in Science suggest that like humans, chimpanzees have undergone substantial evolutionary change

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A CLEARER PICTURE

Since Lucy's discovery in 1974 few, if any, ancient hominid skeletons have elicited such excitement in the scientific world as Ardi, largely because of her unusual completeness. Although she likely lived just two million to five million years after the last human and chimpanzee common ancestor did, "Ardi does not tell us what the last common ancestor was," Lovejoy said at the press briefing.....[ More ]

MORE HUMAN HANDS

Ardi's hands, although large—to better climb trees—are a far cry from the stiff, strong hands of today's arboreal chimps. The discovery of so many hand bones mark an important discovery for scientists in the field, as other ancient hominid specimens, including Lucy, lack much of the crucial fossil evidence to assert that these animals did not walk on their knuckles as modern chimps and gorillas do.....[ More ]

FINGERED FOOT

The feet of Ar. ramidus are unlike those of latter Lucy or present-day great apes. A widely detached first toe would have allowed for handy grasping of tree branches and trunks to facilitate climbing, as getting around in its forested environment would have been the primary method of travel.....[ More ]

PRIMITIVE PELVIS

Although Ardi's pelvis was badly damaged, researchers were able to reconstruct it using CT scans. The results show that Ar. ramidus already had adaptations—far different from today's tree-dwelling chimps—that would have allowed it to walk upright, if not as adeptly as the latter, 3.2-million-year-old Lucy, an Australopithecus afarensis .....[ More ]

SMALLER CANINES

In humans [ left ] the canine teeth are only slightly longer than the rest of the teeth, whereas male chimpanzees [ right ] have long and fearsome canines that they use in conflicts over females. Male Ar.....[ More ]

REBUILDING THE BRAIN

Ardi's skull was badly crushed, but researchers reconstructed its pieces using computer tomography (CT). Unlike the later Australopithecus , the "Lucy" species, Ar. ramidus still had a relatively small head and brain.....[ More ]

PROFILING A 4.4-MILLION-YEAR-OLD COUSIN

Ardipithecus ramidus —"Ardi"—appears to have many features more primitive than both humans and chimps, reinforcing the idea that our last common ancestor was not like modern chimpanzees after all.....[ More ]

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