The Wisdom of Groups

Abstract

O ne day in the fall of 1906, the British scientist Francis Galton left his home in the town of Plymouth and headed for a country fair. Galton was 85-years-old and beginning to feel his age, but he was still brimming with curiosity that had won him renown—and notoriety—for his work on statistics and the science of heredity. And on that particular day, what Galton was curious about was live stock. So begins the first paragraph of a fascinating book, The Wisdom of Crowds, by James Surowiecki (2005). As we learn in the following pages, Galton, in his visit to the fair, was captivated by a weight-judging competition. A fat ox was on display, and the crowd of onlookers could buy a ticket to guess the weight of the animal after it had been slaughtered and dressed. Farmers, butchers, and just plain folks were among the 800 souls who tried their luck. The best guessers would win prizes. Galton’s interest in democracy suggested to him an experiment. After the contest was over, he collected the tickets from the event organizers, tallied up the values of the guesses, and took their average, suspecting that they would be rather off the mark. Nothing could be further from the truth. The average guess was 1,197 pounds and the true weight of the slaughtered and dressed ox was 1,198 pounds. Galton (1907) wrote in his paper in Nature, “The result seems more credible to the trustworthiness of a democratic judgment than might have been expected.” Surowiecki piles on example after example of how intelligent crowds can be smarter than the most knowledgeable individual. The average guess of the crowd that estimates the number of jelly beans in a jar is almost always close to perfect. This, Surowiecki argues, is the reason for such unexpected successes as Wikipedia and Google. Who could imagine that Wikipedia would be so accurate given that it permits anyone to edit everything? The answer turns out to be that when people in a crowd make independent estimates, individual errors and bias are quickly compensated for by contrary opinions. This system is selfcorrecting. Actually, so is the scientific enterprise. No one person controls the outcome. It shares this characteristic with Wikipedia—it is not the wisdom of an individual that counts so much as the wisdom of the crowd. Evolution works the same way. Populations shift their genotype because of the average success of certain phenotypes that carry beneficial alleles.