The influence of polygenismover twentieth-century medicine andracial science has been an underdeveloped area of study. During the period referred to by historians as the 'eclipse of Darwinism', assumptions about separate human ancestry often structured debates across the USA over whether racial heredity was responsible for 'innate dispositions' toward certain diseases. This article explores how polygenist carryovers made their way into early twentieth-century medical and public health studies on the links between race and venereal disease during the American social hygiene movement (1910-40). It also recovers the work of the African-American physician, ethicist, and social hygienist, Dr Charles V. Roman, who stressed during this period that the idea of common human ancestry should push public health researchers to think more creatively and critically about the social and environmental factors shaping health outcomes and black susceptibility to sexual diseases.

In this paper we use quantitative and qualitative methods to examine how death investigations in Los Angeles County jails disproportionately naturalize death among Black and Latino incarcerated people. Our study is based on an assessment of 58 autopsies, coroner investigator narratives, and toxicology reports produced between 2009 and 2018. We found that the Medical Examiner frequently arrived at natural or undetermined death determinations that minimized the culpability of carceral staff for loss of life that occurred within county jail. In our dataset, Black people were disproportionately classified as natural. Undetermined deaths were almost exclusively Latino. More than 75% of the cases in our study were deaths that occurred before standing trial. Our findings reveal how biomedical knowledge about incarcerated Black and Latino people is used to erase the life-diminishing effects of punishment, neglect, and maltreatment that are central to the project of mass incarceration.