Early Primates May Have Feasted on Soft, Sweet Fruits

An analysis of more than 400 fossilized teeth suggests the creatures weren’t eating many seeds, nuts or other hard foods

White background with fossilized teeth
These fossilized teeth belonged to a Propliopithecus chirobates, a type of early primate that lived between 29 million and 35 million years ago. Towle et al. / American Journal of Biological Anthropology

Early primates may have had a sweet tooth.

Fossilized teeth, preserved for the last 29 million to 35 million years, show very few chips, though they have some cavities, report scientists in a recent study. This suggests the ancestors of apes and humans were feasting on soft, sweet fruits, rather than on hard nuts and seeds.

This dental-derived finding, shared last month in the American Journal of Biological Anthropology, “gives insight into our own evolution, our own dietary changes through time,” says study co-author Ian Towle, a dental anthropologist at the Spanish National Research Center for Human Evolution, to Science News’ Erin Garcia de Jesús.

Scientists looked at 421 preserved primate teeth discovered in a fossil-rich part of Egypt known as the Fayum Depression. They inspected each one thoroughly, making note of any damage—such as fractures, chips or cracks—as well as any decay. The teeth belonged to five genera of ancient primates that once roamed the region: Aegyptopithecus, Parapithecus, Propliopithecus, Apidium and Catopithecus.

People standing on a rock looking out over a landscape
The teeth were discovered in Egypt in an area known as the Fayum Depression. Matt Borths

Roughly 5 percent of the specimens, or 21 teeth, had chips. That’s low, compared to the rate of tooth-chipping among living primates, which ranges from 4 to 40 percent. Primates that eat harder foods tend to have damage on more of their teeth, while those that mainly eat soft foods tend to have fewer chips.

In addition, teeth belonging to two Propliopithecus individuals showed signs of decay (which researchers call “dental caries”) that scientists believe developed while the animals were still alive. These cavities suggest Propliopithecus consumed foods high in sugar.

Considered together, the findings seem to indicate ancient primates ate a diet that primarily consisted of soft fruits. They also suggest the animals mainly lived—and ate—in the trees, because wildlife that forage for food on the ground often accidentally eat grit, which can cause tooth damage.

Two small skulls in hands
Scientists studied teeth that belonged to the Aegyptopithecus (left) and Parapithecus (right) genera, plus three others. Matt Borths

Still, some questions remain about what these animals ate. For example, past research that looked at tooth shape and wear reached the opposite conclusion: that at least two groups of early primates, Apidium and Aegyptopithecus, mostly ate hard foods.

One possible explanation for these divergent findings is that the teeth of early primates were less prone to chipping for some unknown reason, per Science News.

“Fruits have been considered an important component of early primate diet for a long time, but it has been proposed other, harder, foods were also important for some early anthropoid primate groups,” Towle tells Haaretz’s Ruth Schuster. “Our new research addresses this from a tooth-chipping perspective.”

More broadly, teeth have become an important tool for unraveling some of the mysteries of the past. Scientists have used teeth to determine that early Europeans snacked on seaweed, that male woolly mammoths went through musth similar to today’s elephants and that early humans might have cooked their fish before eating it some 780,000 years ago.

“I’m constantly amazed by what I find when examining teeth,” said Kristin Krueger, an anthropologist at Loyola University Chicago, to Smithsonian magazine’s Lorraine Boissoneault in 2018. “They truly are little windows into the life of an individual.”

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