Lucy in the dust with dinos: 'a mosaic creature, that is neither chimpanzee, nor is it human'
It was a bad week for Lucys and for creationists. First we heard the woman who inspired the Beatles' "Lucy in the Sky With Diamonds" died of lupus. Then the world's most famous Lucy - a 3.2 million year old Australopithecus afarensis, long believed to be the oldest human ancestor ever found - was one-upped. Fifteen scientists from 10 countries have jointly announced the discovery of Ardipithecus ramidus, or "Ardi," a 4.4 million-year-old hominid skeleton found in modern Ethiopia that appears to be humankindâ€™s oldest close relative.
The last common ancestor shared by humans and chimpanzees is thought to have lived six or more million years ago, according to the American Association for the Advancement of Science, publisher of the journal Science, where 11 papers explaining the discovery will appear in a special issue Oct. 2.
Though Ardipithecus is not itself this last common ancestor, it likely shared many of the ancestor's characteristics, AAAS said. It is the earliest skeleton known from the human branch of the primate family tree, and was found in 1994 about 45 miles south of the site of Lucyâ€™s last breaths.
Scientists spent 17 years investigating the skeleton of â€œArdi,â€ a small bipedal primate whose skeleton contained enough of the skull, teeth, pelvis, legs, feet, arms and hands to tell us a great deal, researchers said.
Ardi walked on two legs on the ground, but spent time in trees, too; she was probably omniverous; and her limbs were more like those of monkeys or extinct apes than chimpanzees or gorillas. Thatâ€™s intriguing because after Lucyâ€™s 1974 discovery, scientists thought new discoveries of earlier hominids would converge to a chimpanzee-like anatomy, due to the genetic similarity between humans and chimps. Thatâ€™s according to a press release from the Los Alamos National Laboratory, home to one of the scientists involved in the discovery.
"In Ardipithecus we have an unspecialized form that hasn't evolved very far in the direction of Australopithecus. So when you go from head to toe, you're seeing a mosaic creature, that is neither chimpanzee, nor is it human. It is Ardipithecus," Tim White of the University of California-Berkeley, one of the lead authors of the research, added in a press release.
AAAS said the findings suggest that hominids and African apes followed different evolutionary pathways.
â€œWe can no longer consider chimps as â€˜proxiesâ€™ for our last common ancestor,â€ AAAS said in a press release."