Published in 1872, The Expression of the Emotions in Man and Animals was a book at the very heart of Darwin's research interests - a central pillar of his 'human' series. This book engaged some of the hardest questions in the evolution debate, and it showed the ever-cautious Darwin at his boldest. If Darwin had one goal with Expression, it was to demonstrate the power of his theories for explaining the origin of our most cherished human qualities: morality and intellect. As Darwin explained, He who admits, on general grounds, that the structure and habits of all animals have been gradually evolved, will look at the whole subject of Expression in a new and interesting light.

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About the Author: Charles Darwin a Victorian scientist and naturalist, has become one of the most famous figures of science to date. Born in 1809 to an upper-middle-class medical family, he was destined for a career in either medicine or the Anglican Church. However, he never completed his medical education and his future changed entirely in 1831 when he joined HMS Beagle as a self-financing, independent naturalist. On returning to England in 1836 he began to write up his theories and observations which culminated in a series of books, most famously On the Origin of Species by Means of Natural Selection in 1859, where he challenged and contradicted contemporary biological and religious beliefs with two decades worth of scientific investigation and theory. Darwin's theory of natural selection is now the most widely accepted scientific model of how species evolve. He died in 1882 and was buried in Westminster Abbey.

Joe Cain is Senior Lecturer in History and Philosophy of Biology at University College London (UCL). His expertise is in the history of evolutionary studies in the nineteenth and twentieth centuries, Darwin and historical memory. He is also director of the Voices oral history project at UCL, and an expert on the Rhinogradentia, a spectacular group of mammals. His recent books include Descended from Darwin (2008) with Michael Ruse, Sewell Wright Taught Me (2007) and Exploring the Borderlands: Documents of the Committee on Common Problems of Genetics, Paleontology, and Systematics, 1943-1944 (2004).