Darwin spells out in his introduction his three-fold purpose. He will first consider whether man, like all other species, is descended from an earlier form. Then he will discuss the way man has developed. Finally, he will evaluate the differences among the human races.
Darwin develops his arguments through many examples from a wide range of sources. The first two chapters describe physical correspondences between man and the other vertebrates, concluding that to deny a common descent would be unreasonable. Only prejudice and arrogance, he says, would explain a rejection of this evidence.
Man’s mental powers are compared at length with those of the other animals. Darwin finds many animals capable of some reasoning, and he also finds parallels between man’s use of language and the cries of animals. Most significant, perhaps, are his tentative remarks about man’s religious instincts and the instincts of animals.
Darwin devotes eleven chapters to the principles of sexual selection among animals and to their secondary sexual characteristics. The four chapters on birds give much information on the sexual functions of their plumage, their calls, and their behavior patterns.
The last three chapters are a special section on “Sexual Selection in Relation to Man.” Much of the discussion in this part treats the role of beauty in determining marriages. Darwin also studies marriage customs among primitive people.
In conclusion, Darwin emphasizes that humans are descended from “barbarians.” He compares our ancestors to the natives he had seen on Tierra del Fuego. Rather than being distressed by his findings, Darwin insists that man should feel pride at having ascended from lowly origins.
For Further Review
Clark, Ronald W. The Survival of Charles Darwin: A Biography of a Man and an Idea. New York: Random House, 1984. Comprehensive (more than 400-page) but very readable biography that gives background on the conception, composition, and publication of The Descent of Man. Notes, bibliography, and index.
Desmond, Adrian, and James Moore. Darwin . New York: Warner Books, 1991. Chronicles Darwin’s controversial life; focuses on the...
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