Thursday, August 23, 2012

Was Lucy Human?

Donald Johanson and Maurice Taieb (with camera) in 1974, studying the bones of an Australopithecus afarensis specimen later named "Lucy".

Alice C. Linsley

Dr. Jeremy De Silva's research has shown that Australopithecus lacked the large grasping toe typical of tree climbers, and its spine, pelvis, knees, and ankles were made for walking on two legs and not designed for tree climbing.

A recent discovery of a complete fourth metatarsal of A. afarensis at Hadar shows the deep, flat base and tarsal facets that "imply that its midfoot had no ape-like midtarsal break. These features show that the A. afarensis foot was functionally like that of modern humans." (Carol Ward, William H. Kimbel, Donald C. Johanson, Feb. 2011) Read the report here.

Additionally, A. afarensis apparently used polished bone tools, had communal meals, and controlled fire. Some of the earliest evidence of controlled use of fire by humans was found at Swartkrans in South Africa. Other sites that indicate fire use include Chesowanja near Lake Baringo, Koobi Fora and Olorgesailie in Kenya.

A. Afarensis also had human dentition which is quite easily distinguished from that of apes. In humans, the back teeth are larger than the front teeth (not so with apes), and the canines are not pointed. Humans also lack the characteristic diastema or tooth gap found in apes.

Mary Leakey’s 1979 discoveries in Tanzania added to the evidence that humans walked the earth about over 3 million years ago. At Laetoli, about 25 miles south of Olduvai Gorge in Tanzania, Leakey discovered footprints of a man, woman and child created about 3.6 million years ago and preserved under falling ash from the nearby Sadiman volcano. The raised arch and rounded heel of the footprints showed that whoever left these footprints walked as humans today.

However, Donald C. Johanson (co-author of the Feb. 2011 report cited above) had already declared to the term Australopithecus meaning "ape of the south" or "southern ape". Mary Leakey might have objected. She later expressed her regret that “the Laetoli fellow is now doomed to be called Australopithecus afarensis.”

Johanson and Mary Leakey were scheduled to speak at a Nobel Symposium in Sweden in May 1978. The conference honored Mary Leakey, who received the Golden Linnaean Medal from the King of Sweden for her scientific investigations. Mary Leakey was embarrassed when Johanson announced the name - Australopithecus afarensis - for his Afar Triangle finds and included Mary Leakey's 4-million-year Laetoli specimen (jawbone LH4) from Tanzania as an exhibit.

Johanson, who was scheduled to speak before Mary Leakey, scooped her speech. She was upset because Johanson's designation of "ape" was at odds with what she believed to be the evidence. Johanson's label for Lucy and her community stuck though he clearly has doubts based on more recent discoveries as to the accuracy of the ape designation.

The designation of ape is contradicted by the evidence that these archaic humans had oppositional thumbs, short fingers, human dentition, walked upright, and controlled fire. Discoveries in Dikika, Ethiopia indicate that they used flints to scrap, saw, and chop. Two fossilized bones have been found that appear to be marked by stone tools. On the basis of low-power microscopic and environmental scanning electron microscope observations, these bones show unambiguous stone-tool cut marks for flesh removal and to access bone marrow.

The evidence suggests commensality: sharing a meal around a fire. That is a human practice, not one of apes.

Muscle reconstruction provides further evidence that Lucy walked as modern humans do. 

The evidence taken together indicates that Lucy and her community were human, though anatomically archaic humans. What do you think?

Related reading: Maurice Taieb, the Geologist who Discovered the Site Where Lucy was FoundGenesis and Genetics; Biblical Anthropologists Discuss Darwin; The Evolution of Darwinian Evolution; Getting the Facts About Human OriginsIs Genesis Really About Human Origins?

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