Cooking with fire marked an important turning point in human evolution. But based on available evidence, determining exactly when early humans learned to cook is challenging. While researchers have discovered the remains of charred animals and root vegetables, that doesn’t necessarily mean people were grilling up steaks for dinner; they may have simply tossed a dead animal into the fire for disposal.
Now, researchers in Israel say they’ve come up with a clever solution to this problem—and, in the process, they’ve found evidence that early humans may have cooked fish some 780,000 years ago. They described their findings in a new paper published this week in the journal Nature Ecology and Evolution.
Scientists working at the Gesher Benot Ya’aqov archaeological site in Israel found clumps of fish teeth in areas they suspect once contained hearths. But curiously, they didn’t find any fish bones nearby. Perhaps, the considered, early humans had cooked the fish over low heat, which would’ve preserved the teeth but caused the bones to disintegrate over time.
To investigate their theory, the researchers used a technique police often turn to while conducting human forensic investigations. The method involves using X-ray diffraction to measure crystal sizes in tooth enamel, which change when teeth are exposed to fire.
After analyzing teeth collected from the archaeological site, scientists concluded that early humans at Gesher Benot Ya’aqov did not throw the fish directly on hot flames. Instead, they exposed them to temperatures between 390 and 930 degrees Fahrenheit. This suggests that they may have cooked the fish whole in an earthen oven.
Though archaeologists have not found human remains at Gesher Benot Ya’aqov, they have found stone tools there, which suggests that Homo erectus once lived there.
“We do not know exactly how the fish were cooked, but given the lack of evidence of exposure to high temperatures, it is clear that they were not cooked directly in fire and were not thrown into a fire as waste or as material for burning,” says study co-author Jens Najorka, a researcher at the Natural History Museum in London, in a statement.
Though the findings suggest that early humans may have used fire at the site, they’re not conclusive evidence of cooking.
“It is also possible that the teeth exposed to lower temperatures were disposed of in dying fires or were closer to the less intense peripheries of fires,” says Don Butler, an anthropologist at the University of Alaska Fairbanks who was not involved in the study, to NewScientist’s Christa Lesté-Lasserre.