"Hominids were taking advantage of seasonal differences in food items in a savanna environment," Cerling says. "We cannot tell if they were carnivores or scavengers, but it is possible their diet included animals. We are picking up that signal."
The new study was led by Matt Sponheimer, a former University of Utah postdoctoral fellow and now an assistant professor of anthropology at the University of Colorado, Boulder. Other coauthors were Utah's Passey and Cerling; anthropologists Darryl de Ruiter at Texas A&M University and Debbie Guatelli-Steinberg at Ohio State University; and archeologist Julia Lee-Thorp at the University of Bradford, England.
Laser Dentistry on Prehistoric Teeth
The study analyzed four fossil teeth of Paranthropus from Swartkrans, South Africa. A museum loaned them to the researchers. Passey used a laser to remove and vaporize tiny samples of enamel, which then were analyzed in a mass spectrometer to determine the ratio of rare carbon-13 to common carbon-12.
"The previous way to sample tooth enamel was to take a dental drill with a diamond-impregnated bit and basically grind away at the tooth, collect the powder and then analyze that," Passey says.
In the past decade, researchers including Cerling have used "laser ablation" to remove and analyze tooth enamel samples from the large, fossilized teeth of prehistoric horses, rhinos and elephants to determine the animals' diets.
Until now, lasers were too destructive to use on the smaller teeth of human ancestors and their relatives ?even those of Paranthropus, known for relatively large teeth and a strong, heavy jaw.
Passey improved the laser technique. "What I did was fine-tune the method to handle very small samples like human-sized teeth," he says. "If you tried the previous method on a human tooth, you would blast a hole clear
Source:University of Utah