Cannibals and Kings (1977, ISBN 0394407652) is a book written by Marvin Harris. The book presents a systematic discussion of ideas about the reasons for a culture making a transition by stages from egalitarian hunter-gatherer to hierarchically based nationhood as population density increases.

According to Harris, humans shifted from a low-carbohydrate diet largely based on hunter-gatherer sources to a high-carbohydrate diet largely based on agricultural when intensive agriculture began. Harris posits that this diet change resulted in more body fat, which for females led to earlier menarche and a smaller reduction in fertility from nursing infants, which then led to shorter periods between pregnancies. Harris also describes the state of the world in the late 19th century as one of approaching catastrophe as predicted by Malthus (Malthusian catastrophe). Harris then discusses three 20th century innovations that explain this postponement of the catastrophe: the exploitation of petroleum, reliable contraceptives, and social changes in some cultures that make smaller families more desirable.