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Understanding Aging after Darwin
Published in Shamim I. Ahmad, Aging: Exploring a Complex Phenomenon, 2017
Healy et al. (2014) interpreted their results in terms of how mode-of-life/ecological factors altered extrinsic mortality, primarily predation. Species that fly and non-volant species that forage in trees or burrow underground (fossorial) will be less exposed to predators. According to the evolutionary theories of aging, organisms subject to low extrinsic mortality will select for longer life spans than organisms that are subject to high extrinsic mortality. However, there are several lines of evidence that this interpretation is probably incorrect.
Effects of the Sex Ratio and Socioeconomic Deprivation on Male Mortality
Published in Archives of Suicide Research, 2020
F. R. Moore, M. Macleod, C. Starkey, I. Krams, T. Roy
A further factor, well known for its relation to mortality, and which may contribute to the complexity of findings described above, is the likelihood of adoption of risk-taking behavioral strategies by individuals as a consequence of environmental harshness. That is, there is a positive relationship across polygynous vertebrates between extrinsic and intrinsic mortality (i.e., the age-specific risk of mortality that is equal across a population in the case of the former, and mortality due to investment in reproduction versus survival in the latter; Clutton-Brock & Isvaran, 2007; Stearns, 1992). Nettle (2010); see also (Uggla & Mace, 2015), for example, argues that men and women living under socioeconomic deprivation have higher extrinsic mortality due to environmental contaminants and cross-generational health effects, so have a shorter future in which to reap the benefits of health behaviors, resulting in increased intrinsic mortality. Although there is evidence that the sex ratio is related to environmental harshness, such that there are fewer males in the population during, for example, economic deprivation (e.g., Catalano, 2003), little is known about whether socioeconomic deprivation interacts with the local sex ratio to influence risk taking.
Evolutionary life history theory as an organising framework for cohort studies: insights from the Cebu Longitudinal Health and Nutrition Survey
Published in Annals of Human Biology, 2020
Christopher W. Kuzawa, Linda Adair, Sonny A. Bechayda, Judith Rafaelita B. Borja, Delia B. Carba, Paulita L. Duazo, Dan T. A. Eisenberg, Alexander V. Georgiev, Lee T. Gettler, Nanette R. Lee, Elizabeth A. Quinn, Stacy Rosenbaum, Julienne N. Rutherford, Calen P. Ryan, Thomas W. McDade
Although a useful framework, there are notable challenges to testing LHT predictions in longitudinal human cohort studies. Most broadly, much of the theoretical foundations of LHT were developed to explain between-species variation in life histories. Although these principles have been used fruitfully to gain insights into human developmental plasticity (Kuzawa and Bragg 2012), they may not always translate to helping explain within-species variation (Stearns and Rodrigues in press). As we discuss in detail elsewhere (Kyweluk et al. 2018), the important role of extrinsic mortality as a predictor of timing of maturity across species (Charnov 1991) may be less applicable to within-species plasticity in humans, in which factors like nutritional sufficiency may play a more central role.