Donald Johanson is the paleoanthropologist who found Lucy’s remains in the Hadar area of central Ethiopia. He and his colleagues named the fossil after the Beatles song “Lucy in the Sky With Diamonds,” which played repeatedly the night he made the discovery.
These days Johanson serves as the founding director of the Institute of Human Origins at Arizona State University. He spoke to The Times about Lucy’s impact on paleoanthropology and what he hopes to find next.
Before Lucy, what was the accepted narrative of human evolution?
In the early 1970s when I first went into the field, there was a tug-of-war going on between Europe and Africa. Most people thought our most primitive origins were in Africa, but where we really became human was Europe.
How did the discovery of Lucy change that?
She shifted, very dramatically, anthropologists’ view of where we obtained our human features. She showed us it happened in Eastern Africa, and more specifically in the Afar region of Ethiopia where she was found.
She also allowed us to say conclusively that upright walking went back as much as 3.5 million years. That was a major leap in our understanding of the sequence of events of human evolution.
How do you know she walked upright?
Because we had her pelvis. It’s a very rare discovery to find a pelvis, and hers is so strikingly different from the pelvis of a four-legged animal like a chimp. A four-legged animal has a high narrow pelvis with the hip bones facing forward. Our pelvis is squat and wide with the hip bones forming a bowl.
Lucy’s body still had relatively short legs and relatively long arms, which is the kind of anatomy we see in more tree-living or arboreal species. So she was an important bridge for us between more ancient sorts of things and more modern sorts of things.
Why was upright walking an evolutionary advantage in Lucy’s time?
Walking upright had the advantage of freeing the forelimbs from locomotor needs, allowing them to be used for other things, like carrying food back to a home base and sharing it with members of one’s own tribe or band.
We don’t know what all the benefits were, but it was obviously a major landmark breakthrough. The apes have been in decline since as long as we can remember, but there are, what, 8 billion of us today?
How has the science of human origins continued to change since Lucy’s discovery?
When I entered the field, we had maybe six or seven different Homo fossil species. Now we have 15 or 20. So what has changed is that we understand it was not a straight line from the most ancestral species to modern humans, that there were many false starts.
Are there major holes in the story of our origins that you would especially like to see filled in?
At the Institute of Human Origins we are working to answer the specific question: What are the evolutionary foundations of modern humans?
The features that distinguish us from all other animals are symbolic language, our cooperation, and a culture that allows us to make cumulative developments that no single individual could make alone. So, how did all of that come about?
I’d also like to know where our particular genus came from — the genus Homo. Everyone in the world is Homo sapien, but there were other, earlier Homos too. Lucy’s species, Australopithecus afarensis, died out about 3 million years ago, but the oldest Homo evidence we have is from 2.3 million years ago. That means the emergence of our own genus happened between 2.3 and 3 million years ago, and that is where people are looking.