Consider first an astonishing fact. Female life expectancy in the record-holding country has risen for 160 years at a steady pace of almost 3 months per year [Fig. 1 and suppl. table 1 (1)]. In 1840 the record was held by Swedish women, who lived on average a little more than 45 years. Among nations today, the longest expectation of life--almost 85 years--is enjoyed by Japanese women [HN2]. The four-decade increase in life expectancy in 16 decades is so extraordinarily linear [r2 = 0.992; also see suppl. figs. 1 to 5 (1)] that it may be the most remarkable regularity of mass endeavor ever observed. Record life expectancy has also risen linearly for men (r2 = 0.980), albeit more slowly (slope = 0.222): the gap between female and male levels [HN3] has grown from 2 to 6 years (suppl. fig. 2) (Oeppen and Vaupel 2002:1029).
The countries change, but the pattern continues. Older and older.
The trajectories [according to which mortality decelerates with age] differ greatly. For instance, human mortality at advanced ages rises to heights that preclud the longevity outliers found in medflies. Such differences demand explanation. But the trajectories also share a key characteristic. For all species for which large cohorts have been followed to extinction, mortality decelerates and, for the biggest populations studied, even declines at older ages. A few smaller studies have found deceleration in additional species. For humans, the insects, and the worms, the deceleration occurs at ages well past normal reproductive ages.
If older individuals contribute to the reproductive success of younger, related individuals, then they promote the propagation of their genes. Hence, in social species, the effective end of reproduction may be much later than indicated by fertility schedules. The deceleration of human mortality, however, occurs after age 80 and the leveling off or decline after age 110, ages that were rarely if ever reached in the course of human evolution and ages at which any reproductive contribution is small (Vaupel et al. 1998:858).
Oeppen J, Vaupel JW. 2002. Broken limits to life expectancy. Science 296:1029--1031. DOI link
Vaupel JW et al. 1998. Biodemographic trajectories of longevity. Science 280:855-860.