Who Was Lucy? The 3.2-Million-Year-Old Skeleton That Walked Upright

Lucy is the nickname of a partial skeleton of Australopithecus afarensis, an early human relative, found at Hadar in Ethiopia on November 24, 1974. She lived about 3.2 million years ago, and about 40% of her skeleton survives. Her pelvis and legs show she walked upright on two feet, while her long arms and curved finger and toe bones suggest she still spent time climbing trees.

Picture a small adult, about 3.5 feet (roughly 1.05 meters) tall, weighing around 28 kg (62 pounds), with an ape-like face and a small brain, striding across open ground. That combination of features is why Lucy became one of the most famous fossils in the world.

How was Lucy found?

Lucy was found by a team co-led by paleoanthropologist Donald Johanson, working in the Afar region of Ethiopia. The Smithsonian’s Human Origins Program credits the discovery of the specimen, catalogued as AL 288-1, to Johanson and Maurice Taieb. The team celebrated that night with the Beatles song “Lucy in the Sky with Diamonds,” and the nickname stuck. In Ethiopia she is also known as Dinknesh, which the Smithsonian translates from Amharic as “you are marvelous.”

The original fossils are kept at the National Museum of Ethiopia in Addis Ababa, according to the Cleveland Museum of Natural History, which made the first casts of the bones. Museums around the world display replicas.

How complete is Lucy’s skeleton?

About 40% of Lucy’s skeleton was recovered. London’s Natural History Museum counts 47 of the 207 bones in a human body, and notes that most of her hand and foot bones are missing. For a fossil this old, that is unusually complete: most early human species are known from teeth, jaws and scattered fragments.

Her sex comes from the shape of the pelvis. An erupted wisdom tooth and fused bones show she was a young adult when she died.

How do we know Lucy walked upright?

Lucy’s hips and legs are built like a walker’s. The Smithsonian points to her short, broad pelvis, which held the upper body upright, and to thigh bones that angle inward from hip to knee. That angle keeps the body’s weight over the knees while striding, as in modern humans. Chimpanzee thigh bones are straighter, the Cleveland Museum notes.

A separate line of evidence comes from Laetoli in Tanzania. There, about 3.6 million years ago, three individuals walked through wet volcanic ash and left a trail of footprints almost 27 meters (88 feet) long. The Smithsonian’s page on the Laetoli footprint trails says the prints show a heel strike followed by a toe-off, as in a modern stride, and a big toe in line with the other toes rather than splayed like an ape’s. The Smithsonian cites them as evidence that Lucy’s species regularly walked upright.

Lucy probably did not walk exactly as we do. The Natural History Museum notes she may not have covered long distances as efficiently as modern humans.

Did Lucy still climb trees?

Very likely, at least some of the time. The Smithsonian notes that her long arm bones and a crest on her upper arm bone point to strong chest and arm muscles, and that her long, curved toe bones resemble those of a tree-climbing ape. The species page adds that A. afarensis had curved fingers suited to climbing.

That has led to a debate about how she died. A 2016 study using CT scans argued that fractures in her shoulder and arms looked like injuries from a fall from a height, perhaps from a tree. The idea is disputed: Johanson and others argue that the breaks could have happened after death, for example from trampling. The Natural History Museum describes the claim as controversial.

Where does Lucy fit in human evolution?

Lucy belongs to Australopithecus afarensis, a species that lived in eastern Africa between about 3.85 and 2.95 million years ago, in what are now Ethiopia, Kenya and Tanzania, according to the Smithsonian’s species page. Males averaged about 151 cm (4 ft 11 in) and 42 kg (92 lb), females about 105 cm (3 ft 5 in) and 29 kg (64 lb). Brain size was usually under 500 cubic centimeters, roughly a third of a modern human’s.

The species is often treated as a possible ancestor of later humans, though how exactly it connects to our genus, Homo, is still argued over as new fossils turn up. Its diet was mostly plants, including leaves, fruit, seeds, roots and nuts, plus insects and probably the occasional small animal such as a lizard.

Fossils this old are dated from the volcanic layers around them, not from the bones themselves. Our guide to how fossils are dated explains the method, and how carbon dating works explains why carbon-14 cannot reach anything close to that age. Much later relatives, the Neanderthals, are covered in who were the Neanderthals.

Why does Lucy still matter after 50 years?

Lucy is one of the clearest pieces of evidence that upright walking evolved long before large brains: her species had a brain about a third the size of ours and hips built for walking. Later finds, such as the Dikika child, a young A. afarensis skeleton from Ethiopia, have filled in how members of the species grew up.

Bottom line

Lucy is a 3.2-million-year-old, roughly 40% complete skeleton of Australopithecus afarensis found in Ethiopia in 1974. She was small, with a chimp-sized brain, yet her pelvis and legs show she walked upright, and her arms show she could still climb. She remains one of the clearest windows on a time when our relatives lived both on the ground and in the trees.

FAQ

Is Lucy the oldest human ancestor?

No. Older hominin fossils are known, but Lucy was one of the oldest and most complete skeletons when she was found in 1974. Her completeness, more than her age, is what makes her famous.

How tall was Lucy?

Lucy stood about 3.5 feet tall, roughly 1.05 meters. The Natural History Museum estimates her weight at about 28 kg.

Where is the real Lucy skeleton?

The original fossils are kept at the National Museum of Ethiopia in Addis Ababa. Most museums, including in the US and UK, display casts.

Why is she called Lucy?

The team played the Beatles song “Lucy in the Sky with Diamonds” the night of the discovery. Her Ethiopian name, Dinknesh, means “you are marvelous” in Amharic.