A short history of nearly everything - Bill Bryson [223]
I had been told that they were posed like that because during the building of the diorama the female figure kept toppling over, but Ian Tattersall insists with a laugh that the story is untrue. “Obviously we don't know whether the male had his arm around the female or not, but we do know from the stride measurements that they were walking side by side and close together—close enough to be touching. It was quite an exposed area, so they were probably feeling vulnerable. That's why we tried to give them slightly worried expressions.”
I asked him if he was troubled about the amount of license that was taken in reconstructing the figures. “It's always a problem in making re-creations,” he agreed readily enough. “You wouldn't believe how much discussion can go into deciding details like whether Neandertals had eyebrows or not. It was just the same for the Laetoli figures. We simply can't know the details of what they looked like, but we can convey their size and posture and make some reasonable assumptions about their probable appearance. If I had it to do again, I think I might have made them just slightly more apelike and less human. These creatures weren't humans. They were bipedal apes.”
Until very recently it was assumed that we were descended from Lucy and the Laetoli creatures, but now many authorities aren't so sure. Although certain physical features (the teeth, for instance) suggest a possible link between us, other parts of the australopithecine anatomy are more troubling. In their book Extinct Humans, Tattersall and Schwartz point out that the upper portion of the human femur is very like that of the apes but not of the australopithecines; so if Lucy is in a direct line between apes and modern humans, it means we must have adopted an australopithecine femur for a million years or so, then gone back to an ape femur when we moved on to the next phase of our development. They believe, in fact, that not only was Lucy not our ancestor, she wasn't even much of a walker.
“Lucy and her kind did not locomote in anything like the modern human fashion,” insists Tattersall. “Only when these hominids had to travel between arboreal habitats would they find themselves walking bipedally, ‘forced' to do so by their own anatomies.” Johanson doesn't accept this. “Lucy's hips and the muscular arrangement of her pelvis,” he has written, “would have made it as hard for her to climb trees as it is for modern humans.”
Matters grew murkier still in 2001 and 2002 when four exceptional new specimens were found. One, discovered by Meave Leakey of the famous fossil-hunting family at Lake Turkana in Kenya and called Kenyanthropus platyops (“Kenyan flat-face”), is from about the same time as Lucy and raises the possibility that it was our ancestor and Lucy was an unsuccessful side branch. Also found in 2001 were Ardipithecus ramidus kadabba, dated at between 5.2 million and 5.8 million years old, and Orrorin tugenensis, thought to be 6 million years old, making it the oldest hominid yet found—but only for a brief while. In the summer of 2002 a French team working in the Djurab Desert of Chad (an area that had never before yielded ancient bones) found a hominid almost 7 million years old, which they labeled Sahelanthropus tchadensis. (Some critics believe that it was not human, but an early ape and therefore should be called Sahelpithecus.) All these were early creatures and quite primitive but they walked upright, and they were doing so far earlier than previously thought.
Bipedalism is a demanding and risky strategy. It means