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Online Course for Teachers: Teaching Evolution

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SESSION 5: How Did Humans Evolve? Is Evolution Still Happening?

Engage Part B: Lucy and Bipedalism

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.

Image of Lucy's skeleton on a table in a labrotory.

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.


Why might bipedalism have been an advantage in early hominids?


What changes in the environment might have exerted selective pressure?

Finding Lucy
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Next: Engage Part C: Build a Concept Map

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