Fifty Animals that Changed the Course of History is a beautifully illustrated book that uncovers the fascinating stories of creatures great and small. These are the animals that have played a central role in the evolution of humankind and modern society, but remain at the periphery of our undertsanding of history. Take, for example, the horse, which has been used in warfare since the fourth millenium BC and helped the Mongols to conquer nearly all of continental Asia, the Middle East, and parts of Europe; or the silkworm, vital to textile manufacturing for over 5,500 years and the trigger for trade between China and Europe along what became known as the Silk Road; or the flea Xenopsylla cheopis, spreader of the Black Death, which claimed up to 100 million lives in the mid-1300s. Often, these animals provide a window onto a specific episode in history, such as the beaver, which drove hunters and tappers into previously unexplored regions of Canada and the northern US as part of the fur trade, or the finch, which helped Charles Darwin to formulate his theory of natural selection. In order to justify the assertion that they literally 'changed the course of history', each animal is judged by its influence in four categories: edible (animals that have shaped agriculture, such as the cow), medical (animals that are 'disease vectors', spreading bacteria and viruses from malaria to the plague), commercial (animals used for trade or in manufacturing), and practical (animals used for transportation or clothing).