A research team at Harvard University has shown that Homo erectus, Homo neanderthalensis and Homo sapiens may have evolved smaller molars compared with other primates as a result of softening their food with tools and fire.

Extinct hominids of the species Homo erectus (the precursors of man or Homo sapiens), which evolved around 1.9 million years ago, may have cooked and processed their food, the study suggests.1

Chris Organ of the Department of Organismic and Evolutionary Biology and his colleagues estimate that humans would spend 48% of the day eating if we were ordinary primates, when the actual percentage of time humans spend eating each day is 5%.

In a comparative analysis of non-human primates, modern humans, and 14 extinct hominids, the team analysed molar sizes, body masses, DNA and other characteristics to infer when the pattern of reduced eating times began.

The evolution of smaller molars is not explicable by the amount of overall evolution in the jaws and heads of hominids. Softening food allowed for smaller molars and reduced eating time.

The theory that extinct hominids may have cooked their food explains the small teeth, jaws, and guts of modern humans.