The discovery of an early hominid skeleton dated at more than three million years old precipitated a change in how human evolution is viewed.
On November 30, 1974, Donald C. Johanson and a coworker discovered small bones on the slope of a desert gully at Hadar in the Afar Triangle region of Ethiopia. These bones belonged to one individual, a unique hominid that did not resemble anything discovered previously. Named Lucy (for the Beatles song “Lucy in the Sky with Diamonds”), the small skeleton was an amazing find and an important link in the search for human ancestors.
Remains of the three-million-year-old hominid Lucy.
The term “hominid” has a very flexible definition, generally meaning an erect-walking primate that is an extinct ancestor of humans. A hominid can be an ancestor of “true” or modern humans, or a relative, such as a modern primate. The few fossils that had been found before 1925 were from different geographic regions. They were also different from one another, and no one knew exactly what they were, how they were related, or their age.
Early efforts to discover the ancestors of humans centered in Europe. Hominid fossils had been found in the Neanderthal Valley
In 1959, L. S. B. Leakey and Mary Leakey discovered the skull of a large Australopithecus robustus
In 1972, Richard E. Leakey, the son of L. S. B. and Mary Leakey, discovered a hominid skull at Koobi Foora in Kenya. He asserted that the skull was definitely that of a human and that it was approximately 2.9 million years old. This skull was the oldest known fossil of a human. If the more advanced genus Homo (to which humans belong) existed at the same time as the more primitive australopithecines, then theories that Homo evolved from australopithecines were wrong. Later, more accurate dating placed the age of the skull at about 1.9 million years.
In November, 1974, during an international expedition in Hadar, Ethiopia, two of the oldest and finest hominid jaw fossils ever found were located. A few days later, a third jaw was found. Richard and Mary Leakey visited the site and confirmed Johanson’s suspicion that the jaws could be Homo with excessively primitive features. The jaws were dated at approximately three million years old, which made them the oldest known Homo fossils.
On November 30, 1974, a few days after the Leakeys had left the Hadar excavation site, Johanson found the nearly half-complete skeleton of Lucy. For three weeks, everyone at the site collected several hundred pieces of bone, which made up approximately 50 percent of the skeleton. Lucy was a tiny-brained individual, approximately 3.5 feet (a little more than 1 meter) tall. The sex of the skeleton was confirmed by the pelvic bones, which must be larger in females in order to permit the birth of large-skulled babies. Lucy walked erect, which confirmed theories that hominids walked erect three million years ago.
More hominid fossils were found in 1975 and 1976. At site 333, the fragments of at least thirteen individuals of various ages and sexes were found scattered on a slope. These fossils were Homo and very different from Lucy. The 1976 season also yielded stone tools, which strengthened the theory that the site 333 fossils were Homo, as there is no evidence that australopithecines made or used tools.
Johanson and Tim White carefully compared the Hadar fossils and the fossils found at Laetoli, Tanzania, where Mary Leakey and White were working. These comparisons indicated that the Hadar and Laetoli hominids were similar and represented a developmental stage between apes and humans. This determination was a departure from Johanson’s early belief that the fossils were Homo. Johanson and White decided that the Hadar and Laetoli hominids were an early, distinct australopithecine. They named these hominids Australopithecus afarensis.
The discovery of Lucy was a significant development in the search for clues to understanding hominid evolution. Lucy was unique in that she was a very old, primitive, and small hominid that did not fit into the known hominid types. She was also the oldest and most complete hominid skeleton that had been found. Although only 40 percent of the skeleton was recovered, bones from both sides of the body were present, allowing paleoanthropologists to reconstruct approximately 70 percent of her skeleton by using mirror imaging. With mirror imaging, existing bones are used to determine what the missing counterpart on the other side of the body looked like.
Because of the evidence of upright walking in a hominid estimated to be millions of years old and because of the small brain size, the question of why hominids began walking upright had to be reexamined. One previous theory was that manual dexterity, increased tool use, and brain development had forced some humans to stand erect in order to carry more with their hands. Lucy’s hands were similar to those of modern humans, but no evidence has been found to suggest that australopithecines made or used tools. Various other theories explaining erect walking were suggested or considered.
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Edey, Maitland A., and Donald C. Johanson. Blueprints: Solving the Mystery of Evolution. Boston: Little, Brown, 1989. Traces the questions of evolution, beginning with groundwork laid by Carolus Linnaeus and Charles Darwin. Interesting for background information; mentions major hominid fossil finds only briefly. Recommended for those interested in more detailed information on evolution at the molecular level. Includes illustrations and bibliography. -
Herbert, Wray. “Lucy’s Family Problems.” Science News 124 (July 2, 1983): 8-11. Discussion of how Australopithecus afarensis fits into human evolution and the renewed controversy over whether Lucy represented something different from other hominid fossils found at Hadar. Serves to illuminate the changing nature of theories in paleoanthropology. Relatively nontechnical and unbiased. Illustrated. -
Johanson, Donald C. “Ethiopia Yields First ’Family’ of Early Man.” National Geographic, December, 1976, 780-811. Presents a very brief summary of Johanson’s work at Hadar, from the survey trip in 1972 through the 1975 field season. Includes excellent photographs and illustrations. -
Johanson, Donald C., and Maitland A. Edey. Lucy: The Beginnings of Humankind. Reprint. New York: Simon & Schuster, 1990. Clearly written work is one of the most complete accounts of the discovery of Lucy available. Relies on Johanson’s journal notes and, in addition to information about the expeditions, tells of the preliminary work and the effects of the discovery on the scientific and general communities. Includes illustrations and bibliography. -
Johanson, Donald C., and James Schreeve. Lucy’s Child: The Discovery of a Human Ancestor. New York: William Morrow, 1989. Discusses the impact of Lucy’s discovery and the controversy raised. Focuses primarily on fieldwork undertaken in 1986 at Olduvai Gorge. Offers additional insight into the difficulties and triumphs of fieldwork. Includes illustrations and bibliography. -
Leakey, Richard E., and Roger Lewin. Origins Reconsidered: In Search of What Makes Us Human. New York: Doubleday, 1992. Leakey describes his discoveries of human origins and relates anthropological terms and theories in layperson’s terms. -
Morell, Virginia. Ancestral Passions: The Leakey Family and the Quest for Humankind’s Beginnings. New York: Touchstone, 1996. An authoritative personal and scientific biography of the Leakeys. Includes photographs. -
Reader, John. Missing Links: The Hunt for Earliest Man. 2d ed. New York: Penguin Books, 1990. Offers a well-written summary of the major people and discoveries in the history of paleoanthropology. Chapters are arranged so that the history flows from the Neanderthal discoveries in 1857 through the emergence of Australopithecus afarensis and related fossils by 1978. Includes illustrations and bibliography.
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