Title: Human life is unlimited - but short,
Abstract: Does the human lifespan have an impenetrable biological upper limit which
ultimately will stop further increase in life lengths? This question is
important for understanding aging, and for society, and has led to intense
controversies. Demographic data for humans has been interpreted as showing
existence of a limit, or even as an indication of a decreasing limit, but also
as evidence that a limit does not exist. This paper studies what can be
inferred from data about human mortality at extreme age. We show that in
western countries and Japan and after age 110 the probability of dying is about
47% per year. Hence there is no finite upper limit to the human lifespan.
Still, given the present stage of biotechnology, it is unlikely that during the
next 25 years anyone will live longer than 128 years in these countries. Data,
remarkably, shows no difference in mortality after age 110 between sexes,
between ages, or between different lifestyles or genetic backgrounds. These
results, and the analysis methods developed in this paper, can help testing
biological theories of ageing and aid confirmation of success of efforts to
find a cure for ageing.