Osborn, Henry Fairfield (1857-1935)

US palaeontologist who did much to promote the acceptance of evolutionary theory in the USA. He emphasiszed that evolution was the result of pressures from four main directions: external environment, internal environment, heredity, and selection. Osborn was born in Fairfield, Connecticut, and studied at Princeton University. He made his first fossil-hunting expedition to Colorado and Wyoming 1877. In 1891 he became professor of biology at Columbia. He was staff palaeontologist with the US Geological Survey 1900-24 and president of the American Museum of Natural History 1908-33. Osborn's evolutionary studies focused on the problem of the adaptive diversification of life. He was particularly concerned with the parallel but independent evolution of related lines of descent, and with the explanation of the gradual appearance of new structural units of adaptive value. Osborn wrote an influential textbook, The Age of Mammals 1910.