The curious case of blending inheritance

For more than a century, geneticists have consistently identified the origins of their science with Gregor Mendel’s experiments on peas. Mendelism, they have said, demonstrated at long last that biological inheritance was not, as had so often been supposed, “blending,” but particulate. Many historians of biology continue to interpret the conflict of biometricians and Mendelians at the start of the twentieth century in these terms, identifying biometry with the (incorrect) blending mechanism. But this view of blending is history as war by other means. While Francis Galton’s contrast between blended and alternate inheritance had become familiar by 1905, he and his interpreters understood the two forms as differing outcomes of breeding, not as rival theories. Only a few biologists in this period went beyond blending as a description of results of breeding to a blending mechanism, and these were not biometricians. Recognizing this, we can see also that statistical methods and models were central to evolutionary genetics right from the start. The evolutionary synthesis, while reshaping their role, did not create it.