A1 Refereed original research article in a scientific journal
Fitness benefits of prolonged post-reproductive lifespan in women
Authors: Lahdenpera M, Lummaa V, Helle S, Tremblay M, Russell AF
Publisher: NATURE PUBLISHING GROUP
Publication year: 2004
Journal:: Nature
Journal name in source: NATURE
Journal acronym: NATURE
Volume: 428
Issue: 6979
First page : 178
Last page: 181
Number of pages: 4
ISSN: 0028-0836
DOI: https://doi.org/10.1038/nature02367
Abstract
Most animals reproduce until they die, but in humans, females can survive long after ceasing reproduction(1,2). In theory, a prolonged post-reproductive lifespan will evolve when can gain greater fitness by increasing the success of their offspring than by continuing to breed themselves(3-6). Although reproductive success is known to decline in old age(1-6), it is unknown whether women gain fitness by prolonging lifespan post-reproduction. Using complete multi-generational demographic records, we show that women with a prolonged post-reproductive lifespan have more grandchildren, and hence greater fitness, in pre-modern populations of both Finns and Canadians. This fitness benefit arises because post-reproductive mothers enhance the lifetime reproductive success of their offspring by allowing them to breed earlier, more frequently and more successfully. Finally, the fitness benefits of prolonged lifespan diminish as the reproductive output of offspring declines. This suggests that in female humans, selection for deferred ageing should wane when one's own offspring become post-reproductive and, correspondingly, we show that rates of female mortality accelerate as their offspring terminate reproduction.
Most animals reproduce until they die, but in humans, females can survive long after ceasing reproduction(1,2). In theory, a prolonged post-reproductive lifespan will evolve when can gain greater fitness by increasing the success of their offspring than by continuing to breed themselves(3-6). Although reproductive success is known to decline in old age(1-6), it is unknown whether women gain fitness by prolonging lifespan post-reproduction. Using complete multi-generational demographic records, we show that women with a prolonged post-reproductive lifespan have more grandchildren, and hence greater fitness, in pre-modern populations of both Finns and Canadians. This fitness benefit arises because post-reproductive mothers enhance the lifetime reproductive success of their offspring by allowing them to breed earlier, more frequently and more successfully. Finally, the fitness benefits of prolonged lifespan diminish as the reproductive output of offspring declines. This suggests that in female humans, selection for deferred ageing should wane when one's own offspring become post-reproductive and, correspondingly, we show that rates of female mortality accelerate as their offspring terminate reproduction.
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