Francis Galton: Pioneer of Heredity and Biometry

Introduction

Introduction Francis Galton made important contributions in many areas of science in the nineteenth century. He explored South West Africa, discovered and named the anticyclone, and wrote a book on fingerprints, in addition to his work on anthropometry, psychology, and photography. But most important were his pioneering studies of heredity, in the course of which he invented the statistical tools of regression and correlation, earning him the title of the father of biometry, the application of statistical methods to evolutionary biology. Galton’s work on heredity was closely linked to the evolutionary theory of his half-cousin Charles Darwin. Darwin proposed that species evolve through descent with modification, and that modification is predominantly due to the operation of natural selection on small inherited variations. The first part of Darwin’s thesis was quickly accepted by contemporary scientists, but his theory of the mechanism of evolution by natural selection was not, because he did not have a convincing theory of heredity to explain how selection acted and because he had no direct evidence of natural selection. Thus the explanation of variability and heredity and their relationship to natural selection have been key questions in the history of Darwinism from the publication of The Origin of Species in 1859 until today. The work of Galton and his followers played a central role in the early history of Darwinism, which has been increasingly recognized by historians of science (Provine 1971, Olby 1985, Gayon 1998). Their work in the application of statistical methods to the biological sciences was equally important (Porter 1986, Stigler 1986 and 1999). This book is an attempt to clarify and explain the development of Galton’s ideas on heredity and biometry, and to place them in their scientific context. xvi Introduction Ernst Mayr divides scientists into romantics and classics: “The romantic is bubbling over with ideas that have to be dealt with quickly to make room for the next one. Some of these ideas are superbly innovative; others are invalid if not silly.... The classic, by contrast, concentrates on the perfection of something that already exists. He tends to work over a subject exhaustively. He also tends to defend the status quo” (1982, 831). Galton was an archetypal romantic, an innovator with the gift of seeing problems in statistical terms, but lacking the mathematical ability and the inclination to push his ideas to their logical conclusion. Relying on intuition rather than mathematical expertise, he made mistakes and was sometimes confused or self-contradictory. He was also rather careless arithmetically; obvious numerical errors have been corrected in what follows without comment. Thus, Galton was a pioneer who left it to others to perfect his ideas. It has been a challenge to present a clear account of these sometimes unclear ideas without distorting them. Apart from the first, biographical chapter, this is an internalist account of the development of scientific ideas, based on the premise that scientific knowledge is not just a subjective social construct (Ruse 1999), though scientists are fallible men and women who are constrained by their peculiar abilities, personalities, and social environment. Social constructionist historians, coming from a background in the social sciences, tend to stress the social context of science history and have little sympathy with “the old internalists who wrenched science from its social context and wrote ghostly histories of disembodied ideas” (Desmond 1989, 21). As a retired scientist, with a lifelong interest in population genetics, evolutionary biology, and biometry , I am more interested in the development of scientific ideas than in their social context, though I hope that I do not present these ideas as entirely disembodied nor wrenched completely out of context. I also hope that this book complements the excellent recent biography by Gillham (2001). The first chapter briefly describes Galton’s life and his position as a member of the Victorian intellectual aristocracy, an aristocracy of talent rather than of birth (Annan 1955). His first work on heredity, which was inspired by reading The Origin of Species, tried to demonstrate the inheritance of human mental abilities and to distinguish between the effects of nature and nurture (chapter 2). This work showed a hereditarian bias, but it laid the foundations of the study of human inheritance by statistical methods. He was also inspired by The Origin of Species to extend the Introduction xvii idea of artificial selection of plants and animals to man, a subject that he later called eugenics (chapter 3...