Order Primates,
Family Hominidae
Australopithecus afarensis
Middle Pliocene, Ethiopia
The genealogy of humankind emerges with the line of australopithecine hominids, which appears to have begun between 4 and 5 million years ago with the appearance of Australopithecus anamensis (“Southern Ape of the Lake”) and its earliest descendants, the well-documented Australopithecus afarensis (“Southern Ape of Afar”). Presumably descended from a divergent group of Miocene apes such as Kenyapithecus, these early species of gracile australopiths are the most primitive known. Among the oldest and most complete remains of an erect-walking ancestral hominid ever found, this amazing afarensis skeleton is dated at about 3.2 million years. Known throughout the world as “Lucy” (from a Beatles song), it was discovered in Radar, Ethiopia in 1974 by Donald Johanson and Tom Gray. Lucy was 3-and-a-half feet tall and about 25 years old when she died. Though her scarcely worn wisdom teeth had only recently erupted, she was already showing signs of bone disease on her spine. Whether she accidentally drowned or quietly laid down in the sand and died, her remains were deposited in the shore of an ancient lake and covered over by sediment until eventually exposed by rain.
Lucy herself had an apelike face with a low forehead, resembling far more her recent arboreal, chimp-like ancestors than her distant Homo descendants. With slimmer hips and narrower birth canals, females apparently gave birth to infants with far smaller heads and brains. Possessing smaller canines than their quadrupedal ancestors, they presumably foraged in family groups for fruits and seeds along the vanished lakes and streams of Ethiopia and Tanzania, possibly sleeping in high tree branches to avoid predators. Disappearing by 2.5 million years ago, this hominid species gave rise to all of the subsequently varied tribes of Australopithecus and Homo.
A controversy arose over the naming of the species because the closer in time the separate species of hominids are to their original common ancestor, the more they look alike, making it difficult to distinguish between them. Close to the ancestor of the gorilla and even closer to that of the chimpanzee, afarensis was among the earliest of the divergent line that led to Homo; in fact the origin of the human race can be traced directly back to this ancient tribe of gracile australopiths. Ranging from 3 to 5 feet in height and weighing from 60 to 90 pounds, afarensis had long arms with slightly curved finger and toe bones, suggesting at least a partially arboreal life. Courtesy of the Institute of Human Origins. National Museum of Ethiopia.
A Day In the Life of Lucy:
...To make inferences about how Lucy’s bones were used in day to day life, the researchers analyzed 3-D digital models of bones built from scans of the fossil. Bones, like drinking straws, are hollow, and if you were to slice them horizontally you’d have a set of bone bangles. The width of each one of those bangles at particular parts of the bone indicate its strength. This width is called cortical thickness. For example, a professional tennis player’s racket arm bone has a larger cortical thickness than that of the other arm.
Lucy’s bones were pretty thick.
“She’s tiny, but for her size, she’s coming in very strong,” said John Kappelman, a paleoanthropologist at the University of Texas at Austin who conceived of the study.
Because there isn’t much evidence for tool use, which could have made her bones stronger, the researchers concluded she must have been climbing.
Click below to watch the video: Finding Lucy.
