Bateman's principle

As Bateman principle of AJ Bateman 1948 established theory is referred to in the reproductive biology to compete after the males for the attention of females and try to fertilize as many females as possible. The reason for this he looks in particular that the gametes of males - the sperm - in comparison to the female gametes are smaller and more numerous. He explained his findings experimentally determined that the variance of the mating and reproductive success is greater in females than in males, so the bandwidth of the reproductive success within the male is larger than in females. Thus, males are more exposed to selection pressure.

In the experiment, from the 1948 Bateman concluded his theory, he brought together each four females and males of fruit fly species ( Drosophila melanogaster ). According to current scientific knowledge, the statistical procedures used by Bateman for his conclusions, not more than sufficiently apply.

There are some animal species in which this principle is not applicable in this simple form, it was expanded in the following years, and generalizes, in particular by Robert Trivers. In 1972, Trivers made ​​it clear that the gender-specific form of parental investment in the offspring - and not gender per se or the Gametengröße - are decisive for whether an individual in the classical sense behaves male or female.