Bookmark and Share

Alex Bäcker's Wiki / Fisher Did Not Predict Sex Ratio of 1
  • If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.

  • You already know Dokkio is an AI-powered assistant to organize & manage your digital files & messages. Very soon, Dokkio will support Outlook as well as One Drive. Check it out today!


Fisher Did Not Predict Sex Ratio of 1

Page history last edited by Alex Backer, Ph.D. 15 years, 2 months ago

Contrary to what is commonly believed (Refs. 1,2), Sir R.A. Fisher did not stipulate that the sex ratio ought to be one. Instead, he wrote that "the sex ratio will so adjust itself, under the influence of Natural Selection, that the total parental expenditure incurred in respect of children of each sex, shall be equal" and that "in man, the males suffered a heavier mortality during the period of parental expenditure...the condition toward which Natural Selection will tend will be one in which boys are the more numerous at birth, but become less numerous, owing to their higher death rate, before the end of the period of parental expenditure...the actual sex-ratio in man seems to fulfill these conditions somewhat closely" (Ronald A. Fisher, The Genetical Theory of Natural Selection, Dover, 1958, p. 159).


Indeed, the 2000 U.S. Census data suggests that the male/female ratio for children under 18 is 1.0518 (an excess of males, as Fisher suggested). By ages 18-64, the male/female ratio has dropped to 0.989.



1: Nature 424, 616-617 (7 August 2003) | doi: 10.1038/424616b

The struggle for sexual inequality

By Göran Arnqvist

"...Ronald Fisher took up this challenge in 1930, noting that every offspring has one mother and one father. Therefore, the sexes on average fare equally well in passing their genes on to the next generation under an even sex ratio..."

2: Matt Ridley: The Red Queen, p. 124.


Comments (0)

You don't have permission to comment on this page.