Can’t Any Body Count?

This paper examines the well-known ‘error’ in the history of human chromosome counting. In the early 1920s, T.S. Painter, supported by a number of independent investigators, placed the count at 48, which was to hold as a fact for more than 30 years. In 1956, Tjio and Levan surprisingly revised the count to 46. The details of the case are used to open up the very practice of counting to theoretical scrutiny. Counting, often taken-for-granted as mundane and transparent, is instead a richly contingent activity entailing categorical judgments and individuation of objects. Inverting the assumption that entities are there in the world waiting to be counted, I propose that particular objects are constituted as such while they are counted. As the chromosome story demonstrates, the techniques, theories, disciplines, and the things themselves co-evolve through practices of counting. Between the 1920s and the 1950s every one of these factors was in flux in the field of human genetics; it should be no surprise that the number of chromosomes changed.