Life history theory

Life history theory (LHT) is an analytical framework[1] designed to study the diversity of life history strategies used by different organisms throughout the world, as well as the causes and results of the variation in their life cycles.[2] It is a theory of biological evolution that seeks to explain aspects of organisms' anatomy and behavior by reference to the way that their life histories—including their reproductive development and behaviors, post-reproductive behaviors, and lifespan (length of time alive)—have been shaped by natural selection. A life history strategy is the "age- and stage-specific patterns"[2] and timing of events that make up an organism's life, such as birth, weaning, maturation, death, etc.[3] These events, notably juvenile development, age of sexual maturity, first reproduction, number of offspring and level of parental investment, senescence and death, depend on the physical and ecological environment of the organism.

The theory was developed in the 1950s[4] and is used to answer questions about topics such as organism size, age of maturation, number of offspring, life span, and many others.[5] In order to study these topics, life history strategies must be identified, and then models are constructed to study their effects. Finally, predictions about the importance and role of the strategies are made,[6] and these predictions are used to understand how evolution affects the ordering and length of life history events in an organism's life, particularly the lifespan and period of reproduction.[7] Life history theory draws on an evolutionary foundation, and studies the effects of natural selection on organisms, both throughout their lifetime and across generations.[8] It also uses measures of evolutionary fitness to determine if organisms are able to maximize or optimize this fitness,[9] by allocating resources to a range of different demands throughout the organism's life.[1] It serves as a method to investigate further the "many layers of complexity of organisms and their worlds".[10]

Organisms have evolved a great variety of life histories, from Pacific salmon, which produce thousands of eggs at one time and then die, to human beings, who produce a few offspring over the course of decades. The theory depends on principles of evolutionary biology and ecology and is widely used in other areas of science.

  1. ^ a b Vitzthum, V. (2008). Evolutionary models of women's reproductive functioning. Annual Review of Anthropology, 37, 53-73
  2. ^ a b Flatt, T., & Heyland, A. (Eds.). (2011). Mechanisms of Life History Evolution : The Genetics and Physiology of Life History Traits and Trade-Offs. Oxford, GB: OUP Oxford.
  3. ^ Ahlström, T. (2011). Life‐history theory, past human populations and climatic perturbations. International Journal of Osteoarchaeology, 21(4), 407-419.
  4. ^ Stearns, S. (1992). The Evolution of Life Histories. Oxford; New York: Oxford University Press.
  5. ^ Hochberg, Z. (2011). Evo-Devo of Child Growth : Treatise on Child Growth and Human Evolution (1). Hoboken, US: Wiley-Blackwell.
  6. ^ Stearns, S. (1976). Life-History Tactics: A Review of the Ideas. The Quarterly Review of Biology, 51(1), 3-47. JSTOR 2825234
  7. ^ Hill, K., & Kaplan, H. (1999). Life history traits in humans: Theory and empirical studies. Annual Review Of Anthropology, 28(1), 397.
  8. ^ Bolger, D. (Ed.). (2012). Wiley Blackwell Companions to Anthropology Ser. : A Companion to Gender Prehistory (1). Somerset, US: Wiley-Blackwell.
  9. ^ Preston, S. D., Kringelbach, M. L., & Knutson, B. (2014). The Interdisciplinary Science of Consumption. Cambridge, US: The MIT Press.
  10. ^ Morbeck, M., Galloway, A., & Zihlman, A. The Evolving Female : A Life-history Perspective. (1997). Princeton, N.J.: Princeton University Press