In a posthumously published book, Carter, a physician in New Orleans, argues that viral resistance is developed through exposure and then passed through family lines. He states: "Moreover the African negro, although contracting yellow fever as readily as other races, has it more mildly and rarely dies of it, his reaction being what one would expect in a race exposed to the infection for many generations. Consequently the author is of the opinion that the available biological evidence is altogether in favour of an Old World-West African-origin of yellow fever, and this is wholly consistent with the historical evidence."

While not an argument for biological determinism, Carter's scholarship will be used to argue that resistance and vulnerability to pathogens are inherent traits based on race, with race seen as a "natural" result of evolving within specific environments.