Studies offer new insight into diets of early human ancestors

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SALT LAKE CITY – A University of Utah professor and some students have worked on a more distinct timeline of how the diet of early human ancestors evolved.

Biology Professor Thure Cerling said four new studies show surprising dietary switches in early humans going back 3.5 million years.

"What we're interested in is trying to understand how the diet of early man has changed over millions of years,” he said. "The earliest creature that we've worked on has this forest based diet. Then what we found is that at a later time, closer to us, the early fossils, and this is a new fossil called Kenyanthropus, that creature had a mixed diet.”

Cerling and two graduate students joined researchers in Kenya, where they studied more than 100 previously unexamined teeth from early humans in Africa.

The findings lay out a timeline of dietary evolution that spans 4 million years.

"We can see that using carbon isotopes in the teeth and as we go through time even further, later, about 2 million years ago, we find there are two very distinct lineages of early human relatives,” Cerling said.

The members of one of those lineages only ate certain plants, while another branched out and added some form of grass to their diets.

Researchers said the change in nutrition can be linked with walking upright and larger brains, which may have ultimately shaped humans into what they are today. Researchers said it isn’t clear whether these early human ancestors were eating the grass directly or eating the meat of animals that fed on the grass.

The results of the reports were published this week in the journal Proceedings of the National Academy of Sciences.