Despite Costa Rica having wider income inequality than the United States on the standard measure, its least advantaged citizens outlive Americans in the same position — which is the part researchers cannot fully explain

Yet the mortality gap between people at the top and bottom of the socioeconomic hierarchy is substantially narrower in Costa Rica. So the country with the wider income gap has the smaller mortality gap across socioeconomic groups. They concluded that an important part of the higher mortality among low-SES Americans appears linked to unhealthy lifestyle factors including smoking and obesity. It is not proof that income inequality doesn’t matter for health, and it doesn’t hand anyone a policy recipe. A simple line from income inequality to mortality inequality doesn’t capture it.