The Japan Times, April 2, 1998

Little Lucy the prehuman walked like a woman

WASHINGTON (Reuters) Lucy, the small prehuman who is a symbol of the ancestors of humanity, got around better than anyone ever thought on her stubby little legs, an anthropologist said Tuesday.
"Lucy was beautifully equipped to deal with her world," Patricia Kramer, a University of Washington anthropologist said at a meeting of the American Association of Physical Anthropology in Salt Lake City.
Lucy is the name given to a set of unusually complete skeletal remains found in Ethiopia in 1974. She was identified as a member of a species of prehuman known as Australopithecus afarensis and was touted as the "missing link" between humans and apes. Scientists have since found even earlier "missing links" but have been trying to learn more about how Lucy and her kin would have lived 3.2 million years ago.
Lucy was about 1 meter tall, weighed about 30 kg and would have had a small stride.
Kramer, who is also a civil engineer, applied mathematics to her study of Lucy. She used equations like one developed to calculate whether a cargo door on an airliner will close properly.
"The equations can predict how much energy is required for something to move in space," Kramer said in a statement released ahead of her presentation.
"If you take them and develop models that take into account different leg lengths for Lucy and modern humans and calculate the different levels of energy required for each, the result is a comparison of how much energy is required for Lucy and a modern human to move at any speed."
So Kramer used various walking speeds and compared Lucy to a modern woman 167-cm tall.
She figured Lucy would have walked about at a stroll.
"Lucy was a small-speed forager and walked from one patch of trees to another," Kramer said.
"Her environment was plentiful enough so that there was no demand for her to walk fast or go very far. So her day-range was pretty small, but it allowed her to get enough to eat and be very efficient at walking."
The fossil evidence shows that Australopithecines died out about 2 million years ago and were replaced by the longer-legged models Homo habilis and Homo erectus.
"Probably the environment changed and food became less abundant, so it became necessary for Lucy's descendants to have a larger dayrange," Kramer said.
In 1996 Robin Crompton of the University of Liverpool in England and colleagues did studies that found Australopithecus must have walked upright, rather than in the ungainly crouch previously attributed to the species.
They used a computer model of the way humans walk now and fed in Lucy's proportions. When Lucy's computer model was asked to walk in a crouch like a chimpanzee, she fell over.
Bones of an even older species, Australopithecus anamensis, indicated early hominids walked upright as early as 4 million years ago.