page_title: Lucy (Australopithecus)
section_title: Ambulation
hierarchical_section_title: Lucy (Australopithecus) / Notable characteristics / Ambulation
caption_attribution_description: Lucy - Cleveland Natural History Museum
context_page_description: Lucy is the common name of AL 288-1, several hundred pieces of fossilized bone representing 40 percent of the skeleton of a female of the hominin species Australopithecus afarensis. In Ethiopia, the assembly is also known as Dinkinesh, which means "you are marvelous" in the Amharic language. Lucy was discovered in 1974 in Africa, at Hadar, a site in the Awash Valley of the Afar Triangle in Ethiopia, by paleoanthropologist Donald Johanson of the Cleveland Museum of Natural History.
  The Lucy specimen is an early australopithecine and is dated to about 3.2 million years ago. The skeleton presents a small skull akin to that of non-hominin apes, plus evidence of a walking-gait that was bipedal and upright, akin to that of humans; this combination supports the view of human evolution that bipedalism preceded increase in brain size. A 2016 study proposes that Australopithecus afarensis was also to a large extent tree-dwelling, though the extent of this is debated.
context_section_description: One of the most striking characteristics of the Lucy skeleton is a valgus knee, which indicates that she normally moved by walking upright. Her femur presents a mix of ancestral and derived traits. The femoral head is small and the femoral neck is short; both are primitive traits. The greater trochanter, however, is clearly a derived trait, being short and human-like—even though, unlike in humans, it is situated higher than the femoral head. The length ratio of her humerus (arm) to femur (thigh) is 84.6%, which compares to 71.8% for modern humans, and 97.8% for common chimpanzees, indicating that either the arms of A. afarensis were beginning to shorten, the legs were beginning to lengthen, or both were occurring simultaneously. Lucy also had a lordose curve, or lumbar curve, another indicator of habitual bipedalism. She apparently had physiological flat feet, not to be confused with pes planus or any pathology, even though other afarensis individuals appear to have had arched feet.
caption: Lucy skeleton reconstruction at the Cleveland Museum of Natural History
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