Giants among all whales, they have the largest brains of any creature on Earth. Males can reach a length of 62 feet and can weigh upwards of 50 tons. Hal Whitehead presents a clearer picture of the ecology and social life of sperm whales than ever before. Based on almost 2 decades of field research, he describes their biology, behaviour, and habitat; how they organize their societies; and how their complex lifestyles may have evolved in this unique environment. He explores the crucial role that culture plays in the life of the sperm whale, and traces the consequences of this argument for both evolution and conservation. Whitehead builds a general model of how the ocean environment influences social behavior and cultural evolution among mammals as well as other animals.