Following up on my post from yesterday on the evolutionary history of human longevity, there is a timely article out today in Current Biology on lifespan and condition-dependent mortality. The paper, by Hwei-Yen Chen and Alexei Maklakov, uses an experimental nematode model to play around with random versus non-random, or environmental/condition-dependent, sources of mortality:
We provide experimental evidence for the theory that aging evolves via condition-environment interactions. We show that when selection is condition dependent, high mortality rate leads to the evolution of increased longevity, defined here as mean adult life span in the absence of extrinsic mortality hazard. In order to test the evolutionary theories of aging, one must separate the effects of mortality rate (i.e., high versus low) and mortality source (random versus condi- tion dependent).
Again, playing off what I wrote yesterday, human populations can be subject to highly varied, but relatively stable, condition-environment interactions impacting rates of mortality. Environmental hazards across different environments, differing levels of intra-group and/or inter-group violence, dispersal patterns, and food acquisition/production risk are all examples of such potential relationships.
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1. Chen, H.-y. and A. A. Maklakov (2012). “Longer Life Span Evolves under High Rates of Condition-Dependent Mortality.” Current biology : CB. DOI 10.1016/j.cub.2012.09.021
