The footprints at Laetoli are unique evidence of early hominid
behavior. But they are just part of the fossil evidence that depicts the evolution of
humans over time. In 1974, before the Laetoli footprints were discovered, paleontologist
Don Johanson's team had discovered 40 percent of the complete skeleton of Lucy, now known
as Australopithecus afarensis. Lucy's skeleton was clearly different from other
primates. Her knees were able to lock, her femur slanted inward and her large toe was in
line with her other toes, allowing her to walk upright. The discovery of Lucy surprised
paleontologists because although she was unquestionably bipedal, she was remarkably
apelike -- with a brain about the size of a chimpanzee's.
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Learn more about the discovery of Lucy in
Ethiopia by watching the Evolution Library video segment "Finding Lucy." Then,
think about these questions to help you develop a potential hypothesis for bipedalism. Jot
down your ideas below.
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Why might bipedalism have been an advantage in early
hominids? |
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What changes in the environment might have exerted
selective pressure? |
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