Anthropology professor and primate expert Burton combs the evidence for clues to how our ancestors went from observing wild grassland fires to producing and using their own, and how that ability furthered evolutionary development. At the heart of thetext lies a detailed study of light; Burton details the quantity of light produced by various natural sources, from a moonless night to bright sunlight, and discusses how light reception impacts humans. For instance, ""Would a campfire have produced the light necessary to have had a physiological effect on our ancestors?"" Comparing results from a detailed campfire experiment with research on melatonin and circadian rhythms, Burton concludes that, in fact, ""the repercussions throughout hormonal systems and patterns of brain activity over time may be a critical factor in explaining the divergence of our species."" Burton further explores bipedalism, diet and social groups, and discusses scientific evidence for the dating of fire's use. With great detail and concise arguments, this well-sourced work will fascinate armchair scientists with an interest in anthropology and evolution.