Archaeologists have found the ancient remains of a carp-like fish that looks like it may have been cooked in an earthen oven. This in itself wouldn’t be eventful were it not for the age of the remains: dated to 780,000 years ago, this is the oldest evidence of controlled cooking by an extremely wide margin, predating previous data by some 600,000 years.

Taming the art of fire

Fire control was probably the most important skill our ancestors ever learned, forever altering the course of human evolution. By being able to start a fire at will and use it, our ancestors could stay warm, cook food, ward off predators and venture into harsh climates that would have been inaccessible otherwise. Fire also altered the social fabric of early human communities, drawing groups of people together and allowing them to stay up late and perform various activities well into the night.

The controlled use of fire predates our species and was likely invented during the Stone Age by Homo erectus, the first of our relatives to have human-like body proportions, with shorter arms and longer legs relative to its torso, and the first hominin to migrate out of Africa. Fossil evidence for H. erectus stretches over more than 1.5 million years, having lived at least up to 250,000 years ago, meaning it likely encountered our own species, Homo sapiens.

While the earliest evidence of controlled fire dates to around 1.5 million years ago, judging from charred wood and oxidized patches of earth found at sites like Koobi Fora, in the Lake Turkana region of Kenya, these early sites likely represent opportunistic use of natural fires. Most archaeologists agree that the habitual use of fire didn’t become a staple of human behavior until about 300,000 to 400,000 years ago.

Bearing this context in mind, this makes the recent revelations from Gesher Benot Ya’aqov in Israel’s northern Jordan river valley all the more remarkable. Think about it: just because archaeologists have found charred material that doesn’t necessarily entail cooking because there’s more to cooking than just throwing game meat in a fire. But the fish remains from Gesher Benot Ya’aqov were not cooked directly in fire, and were not thrown into a fire as waste or as material for burning either. Instead, they were slow-cooked, most likely using an oven.

Cooking: the next step in the evolution of controlled fire

In their new study, an international team of researchers from Israel, the UK, and Germany studied crystals inside the enamel of teeth belonging to fish from the carp family. These crystals grow larger or smaller depending on the heat to which they were exposed. The teeth were found around areas where hearths once burned and the fish themselves were likely caught at the ancient Hula Lake, adjacent to the site.

Using an X-ray diffraction technique adapted from human forensic investigations on ancient fish teeth, the researchers could measure the size of the crystals in the enamel. To correlate the size of these crystals with heat, the researchers performed an experiment in which they cooked and burned black carp at various temperatures from a few hundred degrees up to 900°C (1650°F) and then examined the resulting enamel crystals.

This investigation revealed that the Gesher Benot Ya’aqov fish teeth were exposed to temperatures between 200°C to 500°C and weren’t directly exposed to fire. Based on these findings, lead author Dr. Irit Zohar, a researcher at Tel Aviv University’s Steinhardt Museum of Natural History and curator of the Beit Margolin Biological Collections at Oranim Academic College believes that the ancient humans cooked their caught fish whole, most likely in an earthen oven.

 “This study demonstrates the huge importance of fish in the life of prehistoric humans, for their diet and economic stability. Further, by studying the fish remains found at Gesher Benot Ya’aqob we were able to reconstruct, for the first time, the fish population of the ancient Hula Lake and to show that the lake held fish species that became extinct over time. These species included giant barbs (carp-like fish) that reached up to 2 meters in length. The large quantity of fish remains found at the site proves their frequent consumption by early humans, who developed special cooking techniques. These new findings demonstrate not only the importance of freshwater habitats and the fish they contained for the sustenance of prehistoric man, but also illustrate prehistoric humans’ ability to control fire in order to cook food, and their understanding of the benefits of cooking fish before eating it,” said Dr. Zohar.

Transitioning from eating raw food to eating cooked food had a massive impact on subsequent human development and behavior. Cooked food is much easier to digest, freeing up bodily energy that would have otherwise been necessary to break down and digest nutrients. In time, the structure of our ancestors’ jaws and skulls changed, and the extra energy and free time gained by cooking allowed early humans to develop new social and behavioral systems. Cooking fish, in particular, likely accelerated brain development, providing a ‘quantum leap’ in human cognitive evolution. We know today that fish is rich in omega-3 fatty acids, zinc, and iodine, all of which contribute greatly to brain development.

Many questions and mysteries surrounding the first use of cooking remain though. Habitual cooking didn’t appear across all human populations until much later, some 150,000 years ago. In this respect, the Acheulian hunter-gatherers who were active in the ancient Hula Valley region were true pioneers, who likely possessed extensive knowledge of the life cycles of different plant and animal species. Why this knowledge was lost and rediscovered only much, much later is still a mystery.

The findings appeared in the journal Nature Ecology & Evolution.