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.
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 or marriage.
New types of relationships formed; it was possible for people to live together without marrying and without children.