Fisher's Principle
Fisher's principle explains why for most species, the sex ratio is approximately 1:1. Bill Hamilton expounded Fisher's argument in his 1967 paper on "Extraordinary sex ratios" as follows, given the assumption of equal parental expenditure on offspring of both sexes.
-
- Suppose male births are less common than female.
- A newborn male then has better mating prospects than a newborn female, and therefore can expect to have more offspring.
- Therefore parents genetically disposed to produce males tend to have more than average numbers of grandchildren born to them.
- Therefore the genes for male-producing tendencies spread, and male births become more common.
- As the 1:1 sex ratio is approached, the advantage associated with producing males dies away.
- The same reasoning holds if females are substituted for males throughout. Therefore 1:1 is the equilibrium ratio.
In modern language, the 1:1 ratio is the evolutionarily stable strategy (ESS).
Read more about this topic: Sex Ratio
Famous quotes containing the words fisher and/or principle:
“For anyone addicted to reading commonplace books ... finding a good new one is much like enduring a familiar recurrence of malaria, with fever, fits of shaking, strange dreams. Unlike a truly paludismic ordeal, however, the symptoms felt while savoring a collection of one man’s pet quotations are voluptuously enjoyable ...”
—M.F.K. Fisher (1908–1992)
“The principle goal of education in the schools should be creating men and women who are capable of doing new things, not simply repeating what other generations have done; men and women who are creative, inventive and discoverers, who can be critical and verify, and not accept, everything they are offered.”
—Jean Piaget (1896–1980)