Clues at ancient lake site reveal earliest known cooked meal

By Katie Hunt, CNN

Scientists have found the earliest known evidence of cooking at an archaeological site in Israel.

The shift from eating raw to cooked food was a dramatic turning point in human evolution, and the discovery has suggested prehistoric humans were able to deliberately make fires to cook food at least 780,000 years ago.

The detailed study of fish teeth unearthed at the Gesher Benot Ya’aqov site, situated on the edge of the ancient lake Hula, revealed that some of our early ancestors — most likely Homo erectus — were able to cook fish, said study author Dr. Irit Zohar, a researcher at Tel Aviv University’s Steinhardt Museum of Natural History.

The lakeside dwellers feasted on a large freshwater species, according to Zohar, who is also a curator of the Beit Margolin Biological Collections at Oranim Academic College.

No human remains had been found at the site, but the stone tools matched those found at Homo erectus sites across Africa, Zohar said. She said the lake would have been shallow, and it might have been easy to catch large fish like the extinct Luciobarbus longicep, which could grow up to 6.5 feet (2 meters), by hand.

“This is an incredibly important discovery,” said archaeological geochemist Dr. Bethan Linscott, who wasn’t involved in the study.

“Evidence for the controlled use of fire in the (early Stone Age) … is ephemeral at best, and as such, the evidence of anthropogenically (because of human activity) accumulated and cooked fish remains described here will undoubtedly have a wide impact on the research community,” said Linscott, who is a postdoctoral researcher at the University of Oxford in the United Kingdom.

The shift to eating cooked meals meant humans expended less energy on the intensive work of searching for and digesting fresh, raw food, freeing up more time in which to develop new social and behavioral systems.

“Diet has had a big impact on the evolution of our species. It has been suggested that the consumption of meat in particular contributed to the increase in relative brain size of our early Homo ancestors — but pathogenic bacteria make the consumption of uncooked meat a risky business,” Linscott said.

“Cooking, however, kills bacteria and increases the energetic value of meat — thereby creating a new, reliable food source for early hominins. Understanding when this happened is therefore a topic of great interest, because it might help to explain why our hominin ancestors evolved the way that they did.”

The research was published in the journal Nature Ecology and Evolution on Monday.

Does burning equal cooking?

Previous research by Zohar, who has worked at the site for 16 years, had found that the layers of sediment where stone tools were found — suggesting human occupation — were associated with a high number of fish teeth from two particular species (Luciobarbus longiceps and Carasobarbus canis) that were part of the carp family but now extinct.

There were, however, very few fish bones, which unlike teeth soften under high temperatures and easily decay. Other work by study coauthor Nira Alperson-Afil, professor in the department of Israel studies and archaeology at Bar-Ilan University, had identified traces of hearths — some of the earliest outside Africa.

To determine whether the prehistoric inhabitants of the site actually cooked fish there and didn’t just discard fish remains in a fire, the researchers identified changes in the size of tooth enamel crystals, which respond differently to changes in temperature.

In the experiments, Zohar and collaborator Dr. Jens Najorka, who is X-ray lab manager at the Natural History Museum in London, analyzed 56 teeth belonging to prehistoric and freshwater fish that allowed them to identify the changes caused by cooking at low versus high temperatures. The results suggested the fish were cooked at temperatures between 392 and 932 degrees Fahrenheit (200 and 500 degrees Celsius).

“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,” Najorka said in a news release.

The team was also able to determine that fish were a regular part of the diet — they weren’t just a seasonal treat or a last resort when other sources of food were scarce. The researchers did this by looking at the geochemical composition of oxygen and carbon isotopes in the enamel of the teeth to figure out during which season the fish died. The results suggested that they were cooked and eaten year round.

Early migration

Homo erectus was the first hominin to migrate outside Africa, and the research suggested ancient Lake Hula might have been a key staging post on the route of these early migrations.

Exactly when humans first began cooking fish — or any other type of food — is unknown, and there’s no consensus on when ancient hominins first developed the ability to start fires and cook. Until this study, the earliest hard evidence of the use of fire to cook was by Neanderthals and Homo sapiens, who cooked starchy roots in what’s now South Africa about 170,000 years ago.

The cumulative weight of the evidence put forward in the study suggested the fish was cooked, said John McNabb, a professor at the Centre for the Archaeology of Human Origins at the University of Southampton’s department of archaeology. He was not involved in the study.

“When and where deliberately set and controlled fire first appeared, and when we began to cook our food, are two of the really big questions that researchers into human origins have long sought answers for,” he said via email.

“Fire is not just about safety and protection. It prolongs the working day and provides a really important mechanism for social bonding — we literally built our societies around our fires. Cooking opens up new dietary opportunities and brings new food stuffs on-line, as well as increasing the nutritious potential of what we eat. Was cooking the reason Homo erectus was able to move into strange new territories.”

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