‘Hormones, history, and the shoulders of giants’ begins with accounts of extreme human growth: William Rice, a 7 feet 4 inches tall ‘giant’ who died in 1773, and the Efe people of Northeastern Democratic Republic of Congo who are the shortest of any human population. These accounts illustrate how an understanding of hormones permeates our view of how the body works. Hormones are chemicals that coordinate bodily functions. They are secreted in one location and act in another. They move around in the blood and other fluids, and their effects can last for a few seconds or several weeks. Hormone science began with the discovery of secretin by Ernest Starling and William Bayliss in 1902 and has since advanced rapidly.