Over the last 200 years humans experienced a huge increase of life expectancy. These advances were largely driven by extrinsic improvements of their environment (for example, the available diet, disease prevalence, vaccination, and the state of hygiene and sanitation). In this paper we ask whether future improvements of life-expectancy will be bounded from above by human life-span. Life-span, in contrast to life-expectancy, is conceptualized as a biological measure of longevity driven by the intrinsic rate of bodily deterioration. In order to pursue our question we first present a modern theory of aging and show that immutable life-span would put an upper limit on life-expectancy. We then show for a sample of developed countries that human life-span thus defined was indeed constant until the 1950s but increased since then by about eight years in sync with life-expectancy. In other words, we find evidence for manufactured life-span.
