“…In this study, frailty refers specifically to an individual's age-adjusted relative risk of death before the Black Death (i.e., during normal, nonepidemic times) compared with the rest of the living population of the period. Frailty will be indicated by the presence of at least one skeletal lesion (porotic hyperostosis, cribra orbitalia, linear enamel hypoplasia, periosteal lesions of the tibia, or short femur length) known from prior research to be associated with earlier episodes of infection, under-nutrition, or other forms of physiological stress (10,12,14). The purpose here was to test whether the Black Death killed people indiscriminately-i.e., regardless of frailty as indicated by the presence of skeletal lesions-or whether Black Death mortality behaved like normal, nonepidemic mortality in which individuals with the highest frailty were at the highest risk of death.…”