Stand up straight

Natural History, Dec, 2007 by C. Loring Brace, Viktor Deak, Paul Aizley

Ian Tattersall gives a fine summary of bipedalism in early hominids ["Lucy Goes Walkabout," 10/07] so I was surprised to see that Viktor Deak's cover illustration shows Lucy's close relative in a semi-erect, bent-knee stance. I had the good fortune to examine Lucy when she was in Donald C. Johanson's lab in Cleveland, and I can assure you that the anatomy of the lower back, hips, feet, and knee and ankle joints all provide clear evidence that those early hominids stood just as erect as we do.

C. Loring Brace

University of Michigan

Ann Arbor, Michigan

VIKTOR DEAK REPLIES: The Australopithecus garhi in the illustration (which is part of a larger mural on display at the Houston Museum of Natural Science) is shown in a slightly crouched stance, shielding her child. My intent was to catch her at the moment of pulling away from a possible predator (in this case, the viewer)--a gesture that neither human nor ape would do with locked knees. After years of studying Lucy's bones with Gary Sawyer and Ian Tattersall, I have noted their striking similarity to modern human bones, but one can't ignore the fact there are also a lot of differences. Lucy's bell-shaped, robust upper body and small gluteus maximus (well-suited to climbing) probably gave her a slightly different posture from ours.

Lucy Goes Walkabout, but Arizona State University does not. ASU is in Tempe and the University of Arizona is in Tucson.

Paul Aizley

Las Vegas, Nevada

THE EDITORS REPLY: Indeed! We mistakenly stated that the Institute of Human Origins at Arizona State University, where Donald C. Johanson works, is in Tucson. As several of our readers pointed out, ASU is in Tempe. Thanks for keeping us on our toes.