Lucy Discovered in Ethiopia: 3 Million Years of Evolution

Donald Johanson, Maurice Taieb, Yves Coppens, and Tim White unearthed fragments of a 3.2-million-year-old hominin skeleton in Ethiopia's Afar region on November 30, 1974. The find, catalogued as AL 288-1 and nicknamed "Lucy" after the Beatles song playing at camp, represented approximately 40 percent of a single individual and became the most famous fossil in paleoanthropology. The discovery site was a desolate stretch of the Hadar Formation, where ancient lake sediments had been exposed by millions of years of erosion. Johanson spotted a small arm bone fragment on a hillside and recognized it as hominin. Over the following weeks, the team recovered hundreds of bone fragments from a female who stood about three feet seven inches tall and weighed roughly 64 pounds. The skeleton's completeness was extraordinary for a fossil of its age. Lucy belonged to Australopithecus afarensis, which lived between roughly 3.9 and 2.9 million years ago. Her anatomy contained a striking contradiction: her pelvis and knee showed that she walked upright, yet her brain was only about 400 cubic centimeters, roughly chimpanzee-sized. Her proportionally longer arms and curved finger bones suggested she still spent time in trees. Lucy was a mosaic, an evolutionary transition caught in fossil form. The discovery resolved a debate about human evolution's sequence. Scientists had assumed large brains evolved first. Lucy proved upright walking preceded brain expansion by at least a million years. Her species likely lived in open woodland where standing upright offered advantages in spotting predators and covering distance. Lucy remains in a climate-controlled vault at Ethiopia's National Museum, too valuable for public display.