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In gerontology, late-life mortality deceleration is the phenomenon of hazard rate increasing at a decreasing rate in late life – rather than increasing exponentially as in the Gompertz law – and in some cases plateauing (asymptoting) at a constant rate. Graphically, on a log-linear semi-log plot (linear in the ''x''-axis of age, logarithmic in the ''y''-axis of hazard rate), an exponential function becomes linear, and the Gompertz law amounts to the hazard rate increasing linearly with age. Late-life mortality deceleration corresponds to hazard rate increasing more slowly than linearly (on a log-linear graph), instead curving and possibly plateauing. Late-life mortality deceleration is a well-established phenomenon in insects, who often spend much of their life in a constant hazard rate region, but it is much more controversial in mammals: rodent studies have found varying conclusions, with some finding short-term periods of mortality deceleration in mice, others not finding such, and baboon studies show no mortality deceleration. An analogous deceleration occurs in failure rate of manufactured products; this analogy is elaborated in the reliability theory of aging and longevity.〔〔Economos, A. C. 1979. "A Non-Gompertzian Paradigm for Mortality Kinetics of Metazoan Animals and Failure Kinetics of Manufactured Products", ''AGE'' 2: 74–76.〕 Late-life mortality deceleration was first proposed as occurring in human aging, in (which also introduced the Gompertz law), and observed as occurring in humans in , and has since become one of the pillars of the biodemography of human longevity – see history; here "late life" is typically "after 85 years of age". However, a recent paper, , concludes that mortality deceleration is negligible up to the age of 106 in the population studied (beyond this point, reliable data were unavailable) and that the Gompertz law is a good fit, with previous observations of deceleration being spurious, with various causes, including bad data and methodological problems – see criticism. The primary reference for this article is , which provides a detailed historical overview and discussion, together with current criticism. == Phenomena == Three related terms are used in this context: ;Late-life mortality deceleration :Hazard rate increasing at a decreasing rate (rather than increasing log-linearly as in the Gompertz law). ; :More strongly, hazard rate eventually ''stops'' increasing (or rather, asymptotes towards a limit), and then proceeds at a constant rate (or rather, approaches a constant rate), yielding (slightly sub-)exponential decay, as in radioactive decay. ; This is used synonymously with "mortality leveling-off", or rather to refer to the region where hazard rate is approximately constant. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Late-life mortality deceleration」の詳細全文を読む スポンサード リンク
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