Best known for his theory of evolution, as presented in The Origin of Species(1), Darwin has influenced psychiatry in a number of ways. His theory revolutionalized biology and also laid the foundations for the modern study of sociobiology (2), ethology and comparative psychology (3), and child development (4). His notion of natural selection in the origins of species had a profound influence on Freud (5).
The child and grandchild of physicians, Darwin began medical training at the University of Edinburgh but never completed a medical degree. Darwin’s interest in the expression of emotions (6) led to his work on the communicative aspects of infant crying, the development of affective responses, and the "paradox of altruism" (7). In keeping detailed records of the development of his son (8), Darwin provided one of the first systematic studies of child development, and his interest in development—and the recapitulation of evolution—inspired theorists such as Ernst Haeckel and G. Stanley Hall (9). "My first child was born on December 27, 1839, and I at once commenced to make notes on the first dawn of various expressions which he exhibited, for I felt convinced, even at this early period, that the most complex and fine shades of expression must all have had a gradual and natural origin" (10). Despite recurrent medical problems (11), Darwin was an active and astute observer throughout his life; his work has had a profound influence on medicine as well as on biology and psychology.F1