On the Origin of Species

1859

Charles Darwin (1809–1882)

In September of 1831, Charles Darwin was interviewed by Captain Robert FitzRoy of the HMS Beagle for the position of gentleman companion on a two-year voyage for the purpose of mapping the coast of South America. But instead of two years, the Beagle sailed for more than twice that long on what became a trip around the world. Darwin, as the naturalist on board, busied himself collecting specimens and making careful observations throughout the trip. He filled a large scientific diary with thousands of geological and zoological data.

The Beagle docked at Falmouth, England, on October 2, 1836, nearly five years after it left Plymouth Sound. Darwin spent the next several years carefully considering his data and pondering questions about whether and how species change. Drawing on a range of sources, he eventually settled on a theory of gradual evolutionary change by natural selection. He shared his theory only with a few close friends—until 1858, when he became aware of a very similar theory that had been developed by the British naturalist Alfred Russel Wallace. Fearing that he would not be credited for his years of painstakingly developing his theory, Darwin published his ideas in On the Origin of Species in 1859.

Although almost all of his examples were drawn from observation of animals, Darwin included humans and mental life in his theorizing from the beginning. Darwin made four important contributions to the development of psychology. First, he presented evidence that human beings are part of nature; thus we, like all other forms of life, are subject to the laws of nature. Second, Darwin’s approach made the function of a trait or ability an important aspect of its definition—that is, what does a particular trait or ability do for us? How does it aid survival? Third, Darwin’s theory suggested that human abilities could be compared fruitfully with those of other animals (what we call comparative psychology), and that this comparison aids our understanding of the development of human beings—a field that later came to be called developmental psychology. Finally, his emphasis on the role of natural selection in human variability laid the foundation for a psychology of individual differences, which, in the United States, has had its greatest success as an instrument of social management.

SEE ALSO The Principles of Psychology (1890), Functional Psychology (1896), Universal Expression of Emotions (1971)

A watercolor portrait of Charles Darwin from the late 1830s.

The ladder of evolution, as depicted in the British Natural History Museum.