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:
“... no other railroad station in the world manages so mysteriously to cloak with compassion the anguish of departure and the dubious ecstasies of return and arrival. Any waiting room in the world is filled with all this, and I have sat in many of them and accepted it, and I know from deliberate acquaintance that the whole human experience is more bearable at the Gare de Lyon in Paris than anywhere else.”
—M.F.K. Fisher (1908–1992)
“Help thyself: then everyone will help thee too. Principle of Christian charity.”
—Friedrich Nietzsche (1844–1900)