Food processing began two million years ago

Food processing began with our earliest ancestors, who used tools to cut down on the rigorous chewing required to consume food in the hundreds of millennia before fire — and thence cooking — was discovered, according to a study published in Nature.

Regular use of fire is thought to have begun around 500,000 years ago. But Homo erectus, the first hominin to even begin to approach modern humans in stature, brain size and masticatory apparatus, appeared around 1.5 million years earlier than that.

Homo erectus was a regular carnivore and, as Katherine Zink and Daniel Lieberman explore in the study, raw meat is tough and practically impossible to break down into swallowable pieces just by chewing it. Foods such as roots and tubers were also consumed, but the paper contends that as much as 11 hours per day of chewing time would have been required to consume sufficient kilojoules.

So H. erectus developed tools that are the ancient equivalent to knives, mortars and pestles, with stone tools dating back to at least 3.3 million years ago. A freshly struck flake of stone makes short work of slicing raw meat into morsels and a lump of rock can be used to pound roots and tubers into a paste.

Today’s scientists have estimated that when meat is sliced and roots are pounded, a prehistoric diet of 8300 kJ per day (1/3 raw goat and 2/3 raw yams, carrots and beets) can be achieved with 2.5 million fewer chews a year than if the items are unprocessed. That’s an entire month spent not chewing — which could explain the reduction in tooth size and masticatory muscle mass of H. erectus compared with earlier species, as well as the increase in brain size allowed by the release of more nutrients.

Our ancestors probably also ate fruits and berries, fish and shellfish, nuts, bone marrow, liver and brains, all of which are highly nutritious but much of which needs a deal of slicing and pounding to get at.

Cooking, when it came, enabled yet more efficient nutrient release, as well as killing harmful parasites that raw meat might contain. But, the study authors contend, cooking was merely part of a culinary tradition that was already millions of years old.

Originally published here.