Human mortality improvement in evolutionary context

Abstract

Life expectancy is increasing in most countries and has exceeded 80 in several, as low-mortality nations continue to make progress in averting deaths. The health and economic implications of mortality reduction have been given substantial attention, but the observed malleability of human mortality has not been placed in a broad evolutionary context. We quantify the rate and amount of mortality reduction by comparing a variety of human populations to the evolved human mortality profile, here estimated as the average mortality pattern for ethnographically observed hunter-gatherers. We show that human mortality has decreased so substantially that the difference between hunter-gatherers and today's lowest mortality populations is greater than the difference between huntergatherers and wild chimpanzees. The bulk of this mortality reduction has occurred since 1900 and has been experienced by only about 4 of the roughly 8,000 human generations that have ever lived. Moreover, mortality improvement in humans is on par with or greater than the reductions in mortality in other species achieved by laboratory selection experiments and endocrine pathway mutations. This observed plasticity in age-specific risk of death is at odds with conventional theories of aging.biodemography | cross-species comparison | life history evolution | phenotypic plasticity | human lifespan

The emergence of longevous populations

“…The conquest of early death through collective human efforts to avert mortality from disease and accidents has yielded lifespans that are both longer and more equal in modern industrial humans than at any other time or in any other species in the primate order (26,27,34). Indeed, 21st-century high-income countries occupy different positions in pace-shape space than our recent ancestors, having benefitted from dramatic increases in both life expectancy and lifespan equality.…”

Examining the evidence for major histocompatibility complex-dependent mate selection in humans and nonhuman primates

“…131 One difficulty with the study of human MHC-mediated mate choice is that current humans have ways of manipulating our microbiota, odor, and physical attributes, modifying signals of condition. Our relatively recent environmental modifications have dramatically increased human lifespan and health 132 while at the same time increasing the difficulty for detecting evolutionary associations between mating preferences and fitness benefits. Our ancestral condition may be most closely reflected in remote tribes, like those of the Amazon that are chronically infected with marginally debilitating macroparasites like helminthes, transiently infected with bacteria (staphylococci, streptococci, diarrheal bacteria), and occasionally infected with endemic zoonotic diseases.…”

Taylor's power law in human mortality

“…Gompertz's (1825) law describes the profile of adult mortality with an exponential increase, whereas, e.g., Thiele (1871) and Siler (1983) added terms to model mortality for the young and the old. Burger, Baudisch, and Vaupel (2012) look at the evolution of the fundamental age schedule of human mortality, describing its progress from hunter-gatherers to present highly developed populations; although they state that human mortality levels dropped extraordinarily compared to other species, particularly since 1900, they also show that the shape of human mortality remains fairly stable. Bronikowski et al (2011) show that this age profile of mortality is not only stable for humans over time, but also for primates, whereas Jones et al (2014) emphasize the diversity in these age profiles across various species.…”