The Expression of the Emotions in Man and Animals is a book by Charles Darwin, published in 1872, concerning genetically determined aspects of behaviour. It was published thirteen years after On the Origin of Species and alongside his 1871 book The Descent of Man, it is Darwin's main consideration of human origins. In this book, Darwin seeks to trace the animal origins of human characteristics, such as the pursing of the lips in concentration and the tightening of the muscles around the eyes in anger and efforts of memory. Darwin sought out the opinions of some eminent British psychiatrists, notably James Crichton-Browne, in the preparation of the book which forms Darwin's main contribution to psychology. - Summary by Availle