WRIGHT DIVERSITY AND DRIFT
ALL, ABOUT us, wherever we look or turn, is limitless diversity. No two human beings, except identical twins, are the same. Each of the more than two billion people on this globe is different--different from his parents, from his brothers and sisters, from his relatives, from his countrymen, from others of the same race; in short, from every other individual who lives or ever lived.
On the other hand, the living world is not a mass of random individuals. All of the almost limitless number of individuals are gathered together in an array of families, races, species, and other groups.
How can such diversity be? And how do all of these sharply different individuals happen to be clustered together in groups of various sizes and kinds?
Scholars long have puzzled over these basic problems, but not until recently did a scientific answer become possible. Only as genetics began to learn about the nature of difference and as mathematics was applied to the matter of populations was the way opened for a clearer understanding of why we are both different and alike.
An erudite professor at the University of Chicago has given one of the most enlightening explanations of why each individual is unique and yet a member of a group. His name is Sewall Wright. His investigations brought him close to the starting-point of the modern theory of evolution, which he,