Sex ratio

The sex ratio is the Fisher's principle. Many classification deviate from an even sex ratio, either periodically or permanently. Examples increase parthenogenic species, periodically mating organisms such(a) as aphids, some eusocial wasps, bees, ants, & termites.

The human sex ratio is of specific interest to anthropologists as well as demographers. In human societies, sex ratios at birth may be considerably skewed by factors such(a) as a age of mother at birth & by sex-selective abortion and infanticide. Exposure to pesticides and other environmental contaminants may be a significant contributing component as well. As of 2014, the global sex ratio at birth is estimated at 107 boys to 100 girls 1,000 boys per 934 girls..

Types

In almost species, the sex ratio varies according to the age sorting of the population.

It is generally shared into four subdivisions:

These definitions can be somewhat subjective since they lack form boundaries.