Sex ratio is the ratio of males to females in a population.
The primary sex ratio is the ratio at the time of conception, secondary sex ratio is the ratio at time of birth, and tertiary sex ratio is the ratio of mature organisms. In humans the secondary sex ratio is commonly assumed to be 105 boys to 100 girls (which sometimes is shortened to “a ratio of 105”). In human societies, however, sex ratios at birth or among infants may be considerably skewed by sex-selective abortion and infanticide (see missing women ).
- Atta Batta: A custom of bartering brides