Drilling for Evidence of Prehistoric Dinners
Cerling used a drill to pulverize some tooth enamel into powder, but only 2 milligrams per tooth and only from the broken surface of broken teeth, leaving the original surfaces intact for future study. Still, there was anticipation among officials at the National Museums of Kenya, where the teeth are housed.
"The sound of the drill may make a lot of paleontologists and museum staff cringe, but as the results of this study show, it provides new information that we can't get at any other way," Uno says. "And we've gotten very good at drilling."
Carbon isotope ratios in tooth enamel can reveal whether ancient animals ate plants that used what is called C3 photosynthesis trees (and the leaves, nuts and fruits they produce), shrubs, cool-season grasses, herbs and forbs or plants such as warm-season or tropical grasses and sedges that use what is known as C4 photosynthesis. (Sedges vaguely resemble grasses, but their stems' cross-sections usually are triangular, which means "sedges have edges" when rotated between thumb and finger.)
The study found that not only did the Nutcracker Man Paranthropus boisei not eat nuts or other C3 plant products, but dined more heavily on C4 plants like grasses than any other early human, human ancestor or human relative studied to date. Only an extinct species of grass-eating baboon had a diet so dominated by C4 plants.
Carbon isotopes showed the 22 individuals had diets averaging 77 percent C4 plants such as grasses, ranging from a low of 61 percent to a high of 91 percent.
That's statistically indistinguishable from grass diets of grazing animals that lived at the same time: the ancestors of zebras, pigs and warthogs, and hippos, Cerling says.
"They were competing with them," he adds. "They were eating at the same table."
The researchers also analyzed oxygen isotope compo
|Contact: Lee Siegel|
University of Utah