Australopithecus afarensis: Lucy and the First Family

Australopithecus afarensis is the extinct hominid that lived between 3.7 mya and 2.9 mya. Lucy and the First Family was hominids, creatures with both apelike and humanlike features. Johanson announced in 1978 that he considered them to belong to a new species, which he named Australopithecus afarensis {the southern ape from Afar). He claimed that this species was a direct ancestor of humans. He and others eventually determined that Lucy had lived about 3.18 million years ago and the First Family slightly earlier. The most striking fact that the skeletons of Lucy and the First Family revealed was that they had walked upright, on two legs. The Leakeys and most other paleoanthropologists had believed that human ancestors developed upright walking, large brains, and the ability to make and use tools at about the same time. Johanson suggested, however, that bipedal (two-legged) walking had come almost two million years before the other two changes and perhaps had even caused them. "Lucy proved that the bipedalism was the thing that separated us from the apes," he said in the early 1980s. He proposed that humans had developed through "mosaic evolution," with some parts of the body becoming humanlike while others were still apelike.

Richard Leakey and Mary Leakey and disagreed with Johanson's interpretation of his skeletons, and a widely publicized dispute ensued. The Leakeys, for instance, claimed that the skeletons represented two species, not one. They pointed out that Lucy was delicate in build, only about 3 feet 6 inches tall and weighing 60 pounds or so, but some of the other skeletons seemed to belong to creatures much taller and sturdier. Johanson thought that this was because A. afarensis males differed considerably in size from the females, as is true in gorillas and some other living apes. The Leakeys also doubted that Johanson's supposed new species was an ancestor of the human genus, Homo. These questions are still being debated.

Questionnaire:

• Explain more about the Lucy and the First Family.
• Explain more about the Australopithecus afarensis.