Human Adaptation to the Control of Fire

Charles Darwin attributed human evolutionary success to three traits. Our social habits and anatomy were important, he said, but the critical feature was our intelligence, because it led to so much else, including such traits as language, weapons, tools, boats, and the control of fire. Among these, he opined, the control of fire was probably the greatest ever [discovery] made by man, excepting language.(1:48) Despite this early suggestion that the control of fire was even more important than tool use for human success, recent anthropologists have made only sporadic efforts to assess its evolutionary significance.(2,3) Here we use recent developments in understanding the role of cooked food in human diets to support the spirit of Darwin's offhand remark. We first consider the role of fire in increasing the net caloric value of cooked foods compared to raw foods, and hence in accounting for the unique pattern of human digestion. We then review the compelling evidence that humans are biologically adapted to diets that include cooked food, and that humans have a long evolutionary history of an obligate dependence on fire. Accordingly, we end by considering the influence of fire on various aspects of human biology. We pay particular attention to life history, and also briefly discuss effects on anatomy, behavior, and cognition.