When did the ancestors of humans first start eating meat? Tooth fossils could provide some clues

For decades, scientists have been learning more about the diets of early hominins, particularly their reliance on plants. Yet we still don’t know when these ancestors of humans started eating meat.

This is a frustrating gap in our understanding of human evolution. We think regular meat consumption was one of the main drivers of brain growth and evolution in hominins, because animal products are calorie-dense and easier to digest than unprocessed plant foods. They also contain all the essential amino acids and are rich in biologically important nutrients, minerals and vitamins.

What we do know is that by the time our genus, Homo, emerged over two million years ago, hominins were regularly eating meat. This is clear from their increased reliance at this point on stone tools to butcher and process meat products. We’ve also found fossil bones with cut marks that indicate butchering.

But that doesn’t explain when and where regular meat eating started and which species of our ancestors made that crucial shift.

Now, thanks to fossilised tooth enamel, we’re a step closer to an answer. In a study with several other co-authors, we measured nitrogen isotopes in the enamel from fossilised teeth belonging to the hominin genus Australopithecus, discovered in South Africa’s Sterkfontein Caves. This is one of the oldest known...

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