Baret and Lints [Gerontology 1993;39:252-259] have questioned the inte
rpretation of artificial selection experiments for increased longevity
in Drosophila. They suggest that such experiments cannot demonstrate
the genetic determination of longevity, because line differences in me
an longevity are confounded with erratic temporal variations in life s
pan. Using 15,000 flies from selected and control lines developed by L
uckinbill and Glare [Heredity 1985;55:9-19], we show here that when li
nes are tested simultaneously in a carefully controlled environment, t
hey exhibit markedly different average life spans: selected males live
20 days longer than controls, and selected females live 10 days longe
r. These and other observations leave no doubt about the existence of
heritable variation influencing longevity in Drosophila.