However, one particularity of the human species is that pair bonds are often formed without necessarily having the intention of reproduction.
In modern times, emphasis on the institution of marriage, generally described as a male-female bond, has obscured pair bonds formed by same-sex and transsexual couples, and that many heterosexual couples also bond for life without offspring, or that often pairs that do have offspring separate.
As humans societies have evolved from hunter-gatherers into civilized societies, there have been substantial changes in relations between men and women, with perhaps one of a few remaining biological constants being that both adult women and men must have sexual intercourse for human procreation to happen.
Humans have been compared to other species in terms of sexual behavior.
From about 1700 a worldwide movement perhaps described as the "empowerment of the individual" took hold, leading towards greater emancipation of women and equality of individuals.
Men and women became more equal politically, financially, and socially in many nations.
In the twentieth century, dating was sometimes seen as a precursor to marriage but it could also be considered as an end-in-itself, that is, an informal social activity akin to friendship.
It generally happened in that portion of a person's life before the age of marriage, enabled dates to be arranged without face-to-face contact.
These people will have dates on a regular basis, and they may or may not be having sexual relations.
This period of courtship is sometimes seen as a precursor to engagement.
Women eventually won the right to vote in many countries and own property and receive equal treatment by the law, and these changes had profound impacts on the relationships between men and women. In many societies, individuals could decide—on their own—whether they should marry, whom they should marry, and when they should marry.