WHEN SOCIALLY DETERMINED CATEGORIES MAKE BIOLOGICAL REALITIES: UNDERSTANDING BLACK/WHITE HEALTH DISPARITIES IN THE U.S.* 1. Introduction: When the Social Makes the Biological There remains a broad consensus that current folk racial categories—

There remains a broad consensus that current folk racial categories— those categories usually used on surveys, recognized by tbe U.S. Office of Management and Budget (OMB), and used on census forms and by U.S. Federal Drug Administration (FDA)—do not correspond to meaningful biological categories. Pace some recent attempts to defend the use of folk racial categories as a proxy for ancestry and population-level genetic differences (see e.g., Risch et al. 2002), the links between folk racial groups and ancestral populations remain weak, in part because currently identified folk racial categories are historically contingent social constructs (see e.g., Smedley and Smedley 2005 and cites therein), and are in any event for tbe most part too internally heterogeneous with respect to ancestry to be useñil as a proxy for population-level genetic differences (see Barr 2005, Root 2003, 2005; Bamshad et al, 2004 makes a similar point, but raises the possibility of important exceptions). But the broad failure of folk racial categories to correspond to biologically meaningful population-level genetic differences does not imply that there is no biological reality to folk racial categories; this conclusion would only bold if all important biological differences between populations were genetic. The social importance of folk racial categories for (nearly) every important aspect of social success in the U.S. creates a situation in which (at least some) folk racial categories are correlated with (and causally wrapped up in) important biological differences—for example, the long-standing health disparities between Black and White Americans. Rather than standing as proxies for ancestry or population-level genetic differences, folk racial categories should themselves be recognized as key causal components of biological differences. That these categories are social