Wednesday, April 30, 2008

You Are What You Eat? Maybe Not for Ancient Man

Careful analysis of microscopic abrasions on the teeth of early human "cousins" by resesarchers at Johns Hopkins, University of Arkansas, Cambridge University and Stony Brook University show that although equipped with thick enamel, large jaws and powerful chewing muscles, this ancient species may not have eaten the nuts, seeds or roots their anatomy suggests. Instead, the tooth wear suggests a more general diet, as reported in next week's Public Library of Science One.

"For so many years we've operated under the assumption that the shape of something's teeth, jaws and skull tells us what they habitually ate," says Mark Teaford, Ph.D., a professor of anatomy at Hopkins' Center for Functional Anatomy and Evolution. "But it seems like we had the wrong idea - just because they're capable of eating hard foods doesn't mean that they did - it really makes us rethink some of our basic assumptions."

Using high-powered microscopy to scan tooth surfaces and computer programs that measure imperfections on the surfaces of teeth, the researchers analyzed tooth surfaces from Paranthropus boisei from eastern Africa. According to most researchers, P. boisei's jaw and tooth structure was so specialized and extreme it must have had a very specialized diet. In fact, its anatomy gave it the nickname "Nutcracker Man."

Measuring the microwear from permanent molars of P. boisei from Ethiopia, Kenya and Tanzania dating from 2.27 million years ago to about 1.4 million years ago, the team compared their results with microwear from living primates and other fossils. They found that P. boisei teeth had very little pitting indicative of eating hard foods.

"It seems that while they were perhaps capable of eating harder foods, they generally didn't," says Teaford. "We see similar situations in modern primates, who often like soft fruit. But they can't find that all the time, so occasionally they'll eat harder or tougher foods if they have to."

"Looking at P. boisei you think 'wow, it's a chewing machine,' but that's really an oversimplification." "It may not have been so specialized," he adds.

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