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Trivers-Willard hypothesis

In evolutionary biology, the Trivers-Willard hypothesis proposes that parents should invest more in the sex that gives them the greatest reproductive payoff (grandchildren) with increasing or "marginal" investment. The hypothesis was used to explain why Red Deer mothers would produce more sons when they are in good condition, and more daughters when in poor condition.

Dominance also affects the sex of their offspring, with dominant females birthing more sons and non-dominant females birthing more daughters.

The evolutionary psychologist Satoshi Kanazawa has generalized the Trivers-Willard hypothesis to general heritable traits, as the generalized Trivers-Willard hypothesis.

See also


  • Trivers, R.L., & Willard, D.E. (1973). Natural selection of parental ability to vary the sex ratio of offspring. Science, 179, 90-92.
  • Kanazawa, Satoshi. 2005. "Big and Tall Parents Have More Sons: Further Generalizations of the Trivers-Willard Hypothesis." Journal of Theoretical Biology. 235: 583-590 (pdf).
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Trivers-Willard_hypothesis". A list of authors is available in Wikipedia.
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