Marriage emerged as the most popular institution throughout
history primarily because it was an effective arrangement to
improve the care and upbringing of children. Marriage is not
necessary to have children, but it has been of enormous
importance in the rearing of children. Birds and other non-human
species do not have “marriage”, but both parents are often
involved in raising their offspring. With the sharp declines in
birth rates since 1970 in Western and other rich countries,
including much larger fractions of adults who do not have any
children, both men and women have significantly increased their
ages at marriage, and sharply raised their propensities to
divorce. In 1950, a typical woman and man married at ages 20.3
and 22.8, respectively, whereas now the typical marital ages are
26.0 and 27.7, respectively. These changes in age at marriage
are related to reduced demand for many children, increased
college education of both men and women but especially of women,
much greater labor force participation