Lucy's skeleton showed our ancestors walked upright long before their brains grew large
On 24 November 1974, Donald Johanson skipped updating his field notes to search a gully in Ethiopia that others had already checked twice. As he turned to leave, an arm bone caught his eye. That night, with a Beatles song blaring in camp, the team named the 3.2-million-year-old skeleton Lucy.
Early evolutionists assumed big brains, tools and language would be the first human traits to appear. Raymond Dart's Taung child of 1924 hinted otherwise, looking bipedal but small-brained, yet without more fossils nobody could settle the question. Then in 1970 the French geologist Maurice Taieb recognised the promise of the Hadar Formation in the Afar Triangle and assembled an international expedition. In November 1973 Johanson fitted a shinbone to a thighbone there and saw from the knee angle that its owner, about 3.4 million years old, had walked upright.
Lucy was the jackpot. Over three weeks the team recovered several hundred bone fragments with no duplicates, about 40 percent of one individual of Australopithecus afarensis. A complete pelvic bone and sacrum marked her as female. She stood 1.1 metres tall, weighed 29 kilograms and had a chimpanzee-sized brain, but her angled knee, pelvis and legs worked almost exactly like ours. The combination supported the idea that walking on two legs came before brain expansion. Pamela Alderman suggested the name, after Lucy in the Sky with Diamonds; in Ethiopia she is Dinkinesh, meaning you are marvellous.
Dating was harder. Volcanic rocks at Hadar had been reworked and datable crystals were scarce, so early potassium-argon attempts stalled. When fieldwork resumed in 1990, a refined argon-argon method was applied to two ash layers, one only a metre below the skeleton.
Her bones were reconstructed at the Cleveland Museum of Natural History and returned to Ethiopia, then toured the United States for six years from 2007, despite worries about damage. Fifty years on, researchers agree her species was not the earliest human relative, and that it walked through grassy woodlands rather than open savanna.
Source: Lucy (hominid)
