Ardi (ARA-VP-6/500) are the fossilized skeletal remains of a female Ardipithecus ramidus, an early human-like species 4.4 million years old. It is the most complete early hominid specimen, with most of the skull, teeth, pelvis, hands and feet.[1] While there is no evidence that A. ramidus evolved into modern humans, it shares important characteristics of the early humans who did.
The skeleton shows that chimpanzees are not primitive humans. Chimpanzees and humans evolved along different paths.[2] Chimp feet are specialized for grasping trees. A. ramidus feet are better suited for walking.[3] The canine teeth of A. ramidus are smaller, and equal in size between males and females. This suggests reduced male-to-male conflict, pair-bonding, and increased parental investment.[4] "Thus, fundamental reproductive and social behavioral changes probably occurred in hominids long before they had enlarged brains and began to use stone tools."[5][6]
The word Ardi means "ground floor" and the word ramid means "root" in the Afar language.[7]
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Fossils of A. ramidus were first found in Ethiopia in 1992, but it has taken 17 years to assess their significance.[8] Ardi is a more primitive hominid than the well-known Australopithecine skeleton, Lucy. Standing at 4 feet tall (120 cm) tall and weighing around 110 pounds (50 kg),[9] Ardi was about 6 inches taller than Lucy but almost double her weight. The skeleton was discovered at a site called Aramis in the arid badlands near the Awash River in Ethiopia in 1994. Although it is not known whether Ardi's species developed into Homo sapiens, the discovery is of great significance as Ardi is the oldest known hominid fossil. The discovery was made by a team of scientists led by UC Berkeley anthropologist, Tim D. White [9][10][11] and was analyzed by an international group of scientists that included Owen Lovejoy heading the biology team. On October 1, 2009, the journal Science published an open-access collection of eleven articles, detailing many aspects of A. ramidus and its environment.[12]
Ardi lived more recently than the most recent common ancestor of chimps and humans, but still provides some evidence for what that ancestor was like. Specifically, the skeleton suggests the common ancestor was not as chimp-like as some had supposed,[13] but rather was "probably a palmigrade quadrupedal arboreal climber/clamberer that lacked specializations for suspension, vertical climbing, or knuckle-walking"[14] (i.e. the common ancestor lacked certain important specializations of chimps).
The canine teeth of A. ramidus are smaller, and equal in size between males and females. This suggests reduced male-to-male conflict, pair-bonding, and increased parental investment.[15] "Thus, fundamental reproductive and social behavioral changes probably occurred in hominids long before they had enlarged brains and began to use stone tools."[16]
Researchers infer from the form of Ardi's pelvis and limbs and the presence of her opposable big toe that she was a facultative biped: bipedal when moving on the ground, but quadrupedal when moving about in tree branches.[6][14][17] Ardi had a more primitive walking ability than later hominids, and could not walk or run for long distances.[11] The teeth suggest omnivory, and are more generalized than those of modern apes.[14]
Ardi
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