It is almost the 40th anniversary of one of the most pivotal discoveries from paleoanthropology: Donald Johanson's discovery of "Lucy," a 40% complete skeleton of primitive human ancestor. Why was she so exciting?
Because Lucy walked upright. Not only that, but she was by far the oldest and most complete skeleton that evidenced bipedality. Clues enclosed within the fossils demonstrate this indisputably. These clues include the angle of the femur (imagine a human's leg angle to its pelvis compared with a quadripedal monkey, such as a rhesus macaque), the shape of the kneecap (patella), the pelvis shape, and the spinal curvature necessitated by upright walking.
For further reading, check out the top 7 human evolution discoveries from Tanzania:
Or the beautifully illustrated book "From Lucy to Language," written by Johanson.
Next month paleoanthropologists will celebrate the 40th anniversary of Johanson’s discovery of the elbow bone on November 24, 1974. In the intervening four decades, many more fossils along with other clues have been discovered, rewriting the story of the human race. The evolution of earlier humanlike species and eventually modern humans has grown from the outline of a play with a small cast to an elaborate production with more characters than an Agatha Christie mystery, many remaining enigmatic with relationships still unclear.