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.Behavior patterns are generally unwritten and constantly changing.
Thus, the concept of marriage is changing widely in many countries.
Historically, marriages in most societies were arranged by parents and older relatives with the goal not being love but legacy and "economic stability and political alliances", according to anthropologists.
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.
Neurobiologist Robert Sapolsky constructed a reproductive spectrum with opposite poles being tournament species, in which males compete fiercely for reproductive privileges with females, and pair bond arrangements, in which a male and female will bond for life.
These species-particular behavior patterns provide a context for aspects of human reproduction, including dating.
Today, the institution of dating continues to evolve at a rapid rate with new possibilities and choices opening up particularly through online dating.
Social rules regarding dating vary considerably according to variables such as country, social class, religion, age, sexual orientation and gender.
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.