Geriatric trauma shapes mortality in a tephritid fly

One of the most important questions in research on the biodemography of human aging involves the extent to which early life conditions affect frailty and mortality at advanced ages. We addressed this question experimentally by manipulating dietary conditions of Mexican fruit fly cohorts at younger and older ages. The study yielded five main results: (1) frailty at transfer age (55 days) was far greater in flies maintained on lower quality diet (sugar) at early ages than those maintained on full diets for both sexes; (2) using mortality as a proxy, within-treatment frailty was far greater in males than in females at all advanced ages; (3) remaining life expectancy at advanced ages depended on both past and current dietary conditions for both sexes. Thus the mortality was not memoryless as has been reported in several other studies;. (4) after the initial 1- to 3-day mortality spike due to transfer stress, age-specific mortality for many treatments differed in scale but not in pattern—several were largely age-independent; (5) egg production in older females was drastically affected by past and current conditions. Implications for understanding the effects of early life experience on old age frailty and mortality in human populations will be discussed.