Purity

This article uses the concept of purity to explore the thinking of purebred animal breeders and that of eugenicists in Britain and North America between 1880 and 1920. It begins with an explanation of why such a study is important and continues with the historical background of purity's role in animal breeding over the nineteenth century and an assessment of the theoretical foundations of Francis Galton's eugenics. The article argues that the shared concern with pedigree keeping, which characterized both purebred breeding and eugenics, made it easy for historians to assume that the two fields were more connected than they actually were. In fact, the basis for purity in animal breeding—namely, inbreeding and marketability—could not migrate to eugenics. Pedigree use in animal breeding (inbreeding, consistency, and marketability) actually had little in common with pedigree use in eugenics (evidence of inheritance via statistical quantification). Unpacking this historic connection between animal breeding and eugenics has significance today for such disciplines as animal breeding itself, genetics, politics, and ethics.