Question: What was the scientific significance of the “Lucy” find?
Donald Johanson: Well I think Lucy’s position on the human family tree is what is most important. We proposed way back in 1981 in an article in Science that Lucy was the last common ancestor, her species, the tongue twister, Australopithecus afarensis, named after the Afar region where she was discovered. That she was the last common ancestor to branches that led to us as well as branches that went extinct and today that position has been solidified by the fact that we found nearly 400 specimens of her species, that she is that important bridge between much more ancient and more ape like looking ancestors and more specialized or derived species like other species of Australopithecus and also our own genus homo. So her position on the family tree has been solidified and that is probably the single most important thing about her, that she gives us a real glimpse as these 400 specimens do of what that species looked like at about between three and four million years ago.
Question: What would “Lucy,” and others of her species, have been like in person?
Donald Johanson: Well Lucy herself, if we were… I stopped to pick up a cup of coffee out front, you know, I was looking down the street. Now if we saw her walking down the street, as opposed to the average New Yorker she would have been very short, about three and a half feet tall. She, I would suspect, although we have no definitive proof of this, but because of her antiquity and because of the fact that she probably lived a lifestyle much more like present day chimpanzees, was probably fairly hairy. She had a very projecting face, a very ape like face, rather sloping forehead and a very small skull. Her brain would have been about the size of an average grapefruit for example. A modern human’s skull is about 1,400 cubic centimeters. Her brain was less than 400 cubic centimeters. She would have been walking upright. One thing we would have noticed right away is that she had relatively long arms. Her arms would have come down almost to her knees, so that’s kind of evolutionary baggage which is leftover from the time that her ancestors were living in the trees. Probably lived in a group, I don’t think she was living as a solitary individual, living most of the daylight hours I imagine on the ground, although it’s not impossible that she and other members of her species would make nests in the trees at night. At three and a half feet in stature it’s much safer to be sleeping up in the trees than on the ground. If she had a male member of her species with her the male would have been more like five feet tall. Lucy would have weighed maybe 60 pounds. A male would have weighed up to 100 pounds. Maybe their large size had something to do with their protection of the troop that Lucy and her other members of her species were living in. They lived in more forest environments and that is interesting because our traditional view when we look at television documentaries on human evolution we see the earliest human ancestors walking out on the grasslands and we get the idea that that’s where they first became upright. That’s where they first evolved, but now since 1974, ’75 collecting the fossil animals that are found with Lucy, the kinds of antelopes for example, the kinds of pigs, looking at fossil pollen we know that it was much more forested and that these early upright walking ancestors lived in a more forested environment, much like the ancestors who are living in a forest. They were undoubtedly essentially vegetarians, relying to a large degree on probably fruit, but I would also suspect that from time to time they used twigs and blades of grass like chimpanzees do to extract termites. They would have eaten small vertebrates. They would have eaten bird’s eggs and in the case of Lucy in the same layer, the same strata where we found her we found fossilized crocodile and turtle eggs. Maybe she had been watching a crocodile lay eggs or a turtle and gone down to the edge of the lake where she died and was digging those up and was perhaps taken, you know unawares by a crocodiles. But basically they were vegetarians living in groups in much more forested areas.
Recorded on March 19, 2010
Interviewed by Austin Allen