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Dietary changes accompanied human evolution

Fossil tooth chemistry confirms that hominids moved toward eating grasses, away from tree leaves

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7:00pm, June 3, 2013

The salad days of human evolution saw a dietary shift toward grasses and probably grass-fed animals, analyses of more than 100 fossilized teeth from eight species of ancient hominids indicate.

“These changes in diet have been predicted,” says paleoanthropologist Richard Klein of Stanford University. “But it’s very nice to have some data, and these data support it very strongly.”

Changes in the size and shape of jaws and teeth in both ancient hominids and their ape relatives point to changes in diet. The new study adds to these lines of anatomical evidence chemical analyses that look at different forms of carbon in the fossilized teeth.

The ratio of two types of carbon in tooth enamel reflects diet, says geochemist Thure Cerling of the University of Utah in Salt Lake City, who spent weeks in a vault in the National Museum of Kenya collecting milligram-sized samples of tooth enamel for the analyses.

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