Born in Princeton, New Jersey, Osborn was the son of a renowned paleontologist who was also president of the American Museum of Natural History. Osborn graduated from Princeton in 1909 and attended Cambridge University in England. He then held a variety of jobs, working in freight and railroad yards and serving as a soldier in World War I. He finally took a position at a bank dealing in Wall Street investments.

Throughout his life, Osborn had accompanied his father on paleontological expeditions. As these trips continued into his adulthood, Osborn realized that his true vocation lay not finance but in natural science. In 1935 he accepted a position as secretary of the New York Zoological Society, an organization devoted to the "instruction and recreation of the people of New York." He was named president of the...