On today’s date, November 30th 1974, the hominid referred to as Lucy was discovered in the Afar region of Ethiopia. The discovery of Lucy changed the way scientists looked at the human fossil record forever. Lucy’s bone size and shape indicated that she walked upright, making her the oldest hominid on record to do so. The Australopithecus afarensis remains were discovered by Donald Johanson and was later named after a popular Beatles song at the time, “Lucy in the Sky with Diamonds”.
After an extensive excavation, about 40% of Lucy’s skeletal remains were found. Among those remains included a partial pelvis, leg bones, arm bones, ribs and vertebrae. The discovery of the pelvis helped scientists to discover that the individual was a female and the leg bones helped to determine that she walked upright!
After the discovery of Lucy in Ethiopia, Mary Leakey made a discovery of bipedal footprints preserved in mud at the site
of Laetoli in Tanzania. Johanson and his colleague Tim White compared Mary Leakey’s finds at Laetoli with theirs from Ethiopia, and felt that they were very similar. They categorized them both as Australopithecus afarensis.
Both finds broke a long-standing assumption: that humans developed big brains before walking upright. After 1974, scientists realized that this wasn’t necessarily true, and that brain size overlaps between types of hominids, even as modern people’s brains vary in size without relation to intelligence. This meant they had to look again at why hominids started walking upright. It had been thought that the big-brained creatures started using tools, and to free up their hands, they had to walk upright. But Lucy walked on two feet, and even had “modern” hands, yet showed no evidence of using tools.