Sex ratio: a biological perspective of ‘Sex and the City’

Human Behaviour: Sex Ratio and the City

The ratio of males to females in a population is known to influence the behaviour, life histories and demography of animals. A recent experimental study finds that sex ratio also affects human economic behaviour, and in a manner consistent with evolutionary theory.

Sex and the City

Throughout the industrialized world, young women outnumber young men in urban areas. This paper proposes that such a pattern may be linked to higher male incomes in urban areas. The argument is that urban areas offer skilled workers better labor markets. Assuming that there are more skilled males than females, this alone would predict a surplus of males. However, the presence of males with high...

Sex Ratio Elasticity Influences the Selection of Sex Ratio Strategy

There are three sex ratio strategies (SRS) in nature-male-biased sex ratio, female-biased sex ratio and, equal sex ratio. It was R. A. Fisher who first explained why most species in nature display a sex ratio of ½. Consequent SRS theories such as Hamilton's local mate competition (LMC) and Clark's local resource competition (LRC) separately explained the observed deviations from the seemingly u...

Sexuality: Sex Ratio and Sex Expression

Sex ratio, sex change, and natural selection.

We describe the analogy between the theory of natural selection on sex ratio in newborn gonochores (which will not change sex), and on the age of sex change in sequential hermaphrodites (which are all born into one sex and change to the other later on). We also discuss the conditions under which natural selection favors sequential hermaphrodites over gonochores and vice versa. We show that, in ...