James Hutton, Scottish geologist, 18th century.
© Science Museum / Science & Society Picture Library
Mezzotint by J R Smith after an original by R Cosway. Hutton (1726-1797) is shown holding an ear trumpet to his right ear. Hutton was the originator of uniformitarianism, the theory of uniformity of causes. This proposed that the earth's geological history can be explained by observing the forces currently at work: these forces are the same as those that operated in the past. This theory was not popular at first as it was contrary to religious beliefs, but it gained ground in the 19th century and influenced Charles Darwin's (1809-1882) theories of adaptive evolution. Mathematician John Playfair (1748-1819) supported the Huttonian theory which formed the basis of modern geology.