Using a powerful microscope and computer software, a team of scientists from Johns Hopkins, the University of Arkansas, Worcester Polytechnic Institute and elsewhere has developed a faster and more objective way to examine the surfaces of fossilized teeth, a practice used to figure out the diets of our early ancestors.
By comparing teeth from two species of early humans, Australopithecus africanus and Paranthropus robustus, the researchers confirm previous evidence that A. africanus ate more tough foods, such as leaves, and P. robustus ate more hard, brittle foods. But they also revealed wear patterns suggesting that both species had variable diets. "This new information implies that early humans evolved and altered their diet according to seasonal and other changes in order to survive," said Mark Teaford, Ph.D., professor of functional anatomy and evolution at the Johns Hopkins School of Medicine.
The new approach to studying dental microwear, the microscopic pits and scratches on the tooth surface caused by use, offers a more accurate measurement of the surface's appearance and is described in the August 4 issue of Nature.
"Paleontologists and physical anthropologists have had a somewhat naive view on diet, in part due to the limitations of time-consuming, subjective approaches to analyzing teeth," said Teaford. "So it's a huge step to have a reliable technology that detects subtler diet variations."
A team of scientists from the University of Arkansas and Worcester Polytechnic Institute developed the software, called "scale-sensitive fractal analysis," to analyze fossilized tooth surfaces through a confocal microscope, which allows three-dimensional analysis of an object. "You put the specimen in and the microscope is programmed to step down at fine intervals, perform its series of scans, and collect 3D coordinates for each data point," said Teaford. The result is like a map of the earth that shows mountains, valleys and plains in full relief, only at a microscopic scale.