Lifetime reproductive effort in humans |
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| Authors: | Oskar Burger Robert Walker Marcus J. Hamilton |
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| Affiliation: | 1.Department of Biology, Stanford University, Gilbert Hall, Stanford, CA 94305-5020, USA;2.Department of Anthropology, University of Missouri, 210 Swallow Hall, Columbia, MO 65211, USA;3.Department of Anthropology, University of New Mexico, Albuquerque, NM 87131, USA;4.Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA |
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| Abstract: | Lifetime reproductive effort (LRE) measures the total amount of metabolized energy diverted to reproduction during the lifespan. LRE captures key components of the life history and is particularly useful for describing and comparing the life histories of different organisms. Given a simple energetic production constraint, LRE is predicted to be similar in value for very different life histories. However, humans have some unique ecological characteristics that may alter LRE, such as the long post-reproductive lifespan, lengthy juvenile period and the cooperative nature of human foraging and reproduction. We calculate LRE for natural fertility human populations, compare the findings to other mammals and discuss the implications for human life-history evolution. We find that human life-history traits combine to yield the theoretically predicted value (approx. 1.4). Thus, even with the subsidized energy budget and uniqueness of the adult lifespan, human reproductive strategies converge on the same optimal value of LRE. This suggests that the fundamental demographic variables contained in LRE trade-off against one another in a predictable and highly constrained manner. |
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| Keywords: | life-history theory reproductive effort human reproduction |
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