This issue of Biogerontology addresses whether dietary restriction (DR) "...can increase longevity in all species, particularly in human beings". The possibility that DR can increase longevity in all species seems a trivial issue compared to that of DR's potential efficacy in people. The striking phylogenetic breadth of DR's longevity increasing effect supports the notion of human translatability. The available evidence in primates (human and nonhuman) suggests that it is highly probable that DR will increase the span of good health (and the average lifespan) but the magnitude of this predicted increase is unknown. Robust survival data for monkeys subjected to highly controlled DR will be available in approximately 25 years; similar data for large numbers of human practitioners of DR appear to be many decades away.