Story of Psychology - Morton Hunt [136]
At about the same time, Galton finally came upon the principal interest of his life, the inheritance of intelligence. In 1859 Charles Darwin had published his epochal On the Origin of Species, which vastly impressed Galton. One of Darwin’s basic assumptions was that among the members of any species there are small inheritable variations or differences and that evolution occurs through the natural selection of the fittest members. Although Origin was concerned chiefly with animal species, Galton applied its conclusions to humankind; he reasoned that the evolution of the human species must take place by means of the natural selection of those with better minds and the transmission of their innate mental superiority to their offspring.
This accorded with the impression he had had at Cambridge that many men winning high honors had fathers and brothers who also were honors winners. Galton now conceived of and carried out a valuable, if laborious, research project: he examined and tabulated by family, over the past forty-one years, the top-scoring students in classics and mathematics at Cambridge.4 As he had expected, top honors had been disproportionately won by men in certain families. He published his findings in 1865; from then on, the hereditary nature of mental ability and the improvement of the human race by selective breeding dominated his life and work. Galton must have found it a cruel trick of fate that he and his wife never had any children; a Freudian might suggest that his fixation on the subject was compensation for his failure to reproduce.
Although Galton had been unable to win mathematics honors at Cambridge, his research method was mathematical; like Demosthenes, determined to become an orator despite a speech defect, Galton made his weakness into his greatest strength. His approach to the study of intelligence, or indeed any problem that interested him, was to find something to count so that he could calculate proportions, compare averages, and draw conclusions. In Africa he measured the figures of native women (from a judicious distance) and found them impressive compared with those of Englishwomen. Back home, in cities he visited he kept track of whether every girl he passed on the street was pretty, average, or ugly, and found that the incidence of pretty girls was highest in London, lowest in Aberdeen. At scientific meetings he counted the number of fidgets per minute in a sample of fifty members of the audience and reckoned that fidgeting decreased by more than half when the presentation interested the audience.
Galton’s plan in Hereditary Genius (1869), the first and most influential of his four books on the inheritance of mental ability, was to select a number of unusually gifted people and see how common talent was in their families as compared with the general population. His criterion of unusual mental ability was, at this point, public reputation:
I look upon social and professional life as a continuous examination. All are candidates for the good opinions of others, and for success in their several professions, and they achieve success in proportion as the general estimate is large of their aggregate merits.5
To establish how frequent such reputation (and thus mental ability) is, he counted the obituaries in the London Times for 1868 and some earlier years, and found that those who merited obituaries totaled about 250 per million of the population beyond middle age, or one in four thousand.
He then undertook to compare to this the proportion of eminent persons in the families of a number of illustrious men: English judges since the Reformation, premiers of the past century, and a sampling of famous military commanders,