A search for principles of disability using experimental impairment of Drosophila melanogaster

The results of life table experiments to determine the effects of artificial impairment (leg amputation) in 7500 Drosophila melanogaster adults revealed that the extent to which life expectancy was reduced in impaired individuals was conditional on: (1) leg location and number amputated--front leg had greatest impact and the number of legs amputated directly correlated with mortality impact; (2) age of amputation--the greatest relative reduction in remaining life expectancy occurred when young flies were impaired; (3) vial orientation--mortality in impaired flies was the least when vials held upside-down (most friendly environment) and the greatest when they were right-side up (least friendly environment); and (4) sex--male mortality was increased more than female mortality in nearly all impairment treatments. These results were used to formulate a set of general principles of disability that would apply not only to humans but to all organisms.