William Bateson (1861-1926)

Robinson M. Yost

Early Life

Educated at Rugby and St. John's College, Cambridge, William Bateson earned first-class honors in the natural science tripos. Excelling in embryology and zoology, he took a B. A. in 1883. During several research trips to America, Bateson studied marine biology and met W. H. Brooks at Johns Hopkins University. In 1885, he became a fellow of St. John's College.

Journeys to central Asia and Egypt sharpened his observational skills and interest in evolutionary theory, particularly the origin of species. Returning to Cambridge, Bateson focused on the nature of variation as the key to evolutionary change. By surveying the existing literature and making direct observations, he amassed many examples of variation in plants and animals.

Mutations and Mendelism

Upon examining the evidence, Bateson determined that saltations, or discontinuous variations, drove evolutionary change. Attacking natural selection's focus on continuity, Materials for the Study of Variation Treated with Especial Regard to Discontinuity in the Origin of Species (1894) rejected the idea that adaptive agents alone directed evolution. Saltations, Bateson argued, arose from forces internal to the organism and new characters persisted regardless of adaptive value. He concluded that "the discontinuity of species results from the discontinuity of variation."

Bateson's emphasis on discontinuity led him to appreciate the mutation theory of Dutch botanist Hugo de Vries. De Vries' writings also led Bateson to read the 1865 paper on pea hybridization by Gregor Mendel. Between 1900 and 1902, Bateson became gradually convinced of the universal validity of Mendel's laws.

Controversy with the Biometricians

Opposing natural selection, Bateson drew harsh criticisms from the biometrical school led by W. F. R. Weldon and Karl Pearson. Using a statistical approach to continuous variations, the biometricians endorsed natural selection . Personal animosities between Bateson and Weldon added fuel to the fire as Weldon's attacks on Mendel prompted Bateson's response, Principles of Mendelism: a Defence (1902).

The controversy reached a turning point at the 1904 meeting of the British Association for the Advancement of Science. As president of the zoological section, Bateson challenged Weldon and apparently won the ensuing debate with forceful arguments in favor of Mendelism. Gathering supporters to confirm Mendel's laws experimentally, Bateson named the new science "genetics" in 1905.

Bateson's Achievement

Bateson's collaboration with L. Doncaster, E. R. Saunders, and R. C. Punnett confirmed that Mendel's laws applied to animals as well as plants. Furthermore, breeding experiments with sweet peas and domestic fowl extended Mendelism to phenomena such as reversion, coupling, and complementary factors.

After persistent funding difficulties at Cambridge, Bateson left in 1910 to become director of the John Innes Horticultural Institution. The same year, he cofounded the Journal of Genetics with Punnett. Although rejecting new ideas in later years, Bateson is commonly regarded as the founder of the first school of Mendelian genetics.


By Bateson

Materials for the Study of Variation Treated with Especial Regard to Discontinuity in the Origin of Species, 1894

Mendel's Principles of Heredity: a Defence, 1902

Mendel's Principles of Heredity, 1909

Problems of Genetics, 1913

Scientific Papers of William Bateson (edited by R. C. Punnett), 1928

About Bateson

"Bateson, William." William Coleman. Dictionary of Scientific Biography 1: 505-506

"William Bateson and the Promise of Mendelism." Lindley Darden. Journal of the History of Biology 10 (1977): 87-106

William Bateson, F. R. S. Naturalist. Beatrice Bateson. Cambridge: Cambridge University Press, 1928


Complementary Genes

In particular crosses of plants and animals Bateson and Punnett proposed that two different genes acted in consort.

One of the early studies of Bateson and Punnett clearly illustrated the notion that two genes can affect a single physical character, or phenotype. Crossing certain strains of white-flowered sweet pea plants resulted in all purple flowers in the first generation (F1) progeny. However, when these purple-flowered plants self-fertilized, however, the second generation (F2) gave colored flowers in a ratio of nine purple to seven white. In this case, called a dihybrid cross, F2 usually resulted in phenotypic ratios of 9 : 3 : 3 : 1, meaning four kinds of offspring.

Bateson and Punnett's result was unexpected and seemingly inexplicable. To explain the appearance of only two phenotypic classes, they suggested that two different gene pairs contributed to the production the purple pigment. Purple flowers, therefore, required the presence of both genes. Consequently, the two original white-flowered parents had to be genetically different.

Later researchers confirmed the presence of two dominant genes, designated C and P, needed for the development of purple flowers. The absence of one or both of these complementary genes resulted in white flowers.

Without contradicting Mendel's laws, Bateson's and Punnett's hypothesis convincingly accounted for di-hybrid ratios other than the familiar 9 : 3 : 3 : 1. While confirming Mendelian principles, the concept of complementary genes also extended the explanatory scope of Mendelism.



Elements of Genetics. Edward C. Colin. New York: McGraw-Hill Book Company, Inc., 1956

Principle of Genetics. Eldon J. Gardner. New York: John Wiley & Sons, Inc., 1972 (Fourth Edition)