Ask people who are engaged why they are getting married and they will probably say “love each other" and perhaps "We want to have children." But of course it is not necessary to be married in order to have sexual relations or care for any offspring that may result. As a matter of fact, people everywhere have always limited their sexual activity by getting married. Evidently the biological needs for sex and infant care do not explain the universality of the family. The family must be meeting universal social needs instead.

The Regulation of Sex

Every society has rules about what sorts of people are permitted to marry each other. The strongest, most ancient prohibition against marriage within a certain group is the incest taboo. This rule strictly prohibits sexual intercourse between precisely those people who would be the natural and most accessible partners—close family members. Parents and сhildren and brothers and sisters are never allowed to marry; first cousins are sometimes included in the taboo as well. An extremely rare exception is the society of ancient Egypt, where cest was acceptable for gods; because the kings were believed divine, several of them were married to their sisters or daughters. According to popular belief, the incest taboo is a universal way of preventing the genetic deformities that result from inbreeding.

The incest taboo requires that the exchange of sexual partners must take place between and not within families. On a broader social level the prohibition of incest ensures that every marriage will unite not just two people but two previously unrelated families. The anthropologist Bronislaw Malinowski called this rule of family exchange the principle of reciprocity.

A "Haven in a Heartless World"

Industrial societies have been called a "heartless world" in which the family is uniquely able to provide a private haven of intimate companionship and emotional support. At work and at school, in hospitals and in courts of law, people in modern societies are subject to impersonal rules and bureaucratic regulations.

Of course, husbands and wives do not always give each other unconditional love, acceptance, and companionship. Some marriages are unhappy and some families erupt in violent conflict or drift into sullen indifference. When it is the only institution where personal feelings can be freely expressed, the family can also suffer from "emotional overload." Many people depend solely on their spouses or children for the emotional rewards that others find in their religion or their work. The family is frequently unable to support such a heavy burden, and the ties among its members may break down.

Nevertheless, families provide most of us with love and affection. Many people in a national survey say the family is the most important aspect of their lives.

Other Functions of the Family

Families almost always perform special economic functions. In agricultural societies many families are nearly self-sufficient units, producing most of what they need. In industrial societies, however, families are primarily economic consumers rather than producers. Adult members work for pay outside the family, and children and unemployed housewives are "dependents" who rarely earn any wages at all. Nevertheless, the family functions as an economic unit that provides innumerable services ranging from child care and food production to transportation and secretarial help.

Moreover, all families take on special responsibilities for their members' material needs. Today, in addition to food, clothing, and shelter, family members are also likely to pay for such contemporary requirements as higher education and professional medical care. People who are poor or disabled frequently receive assistance from their families in the form of money or nursing services. The family's willingness to meet such obligations benefits society by providing care and protection for its weakest members.

Forms of Marriage

While the family serves the same basic functions everywhere, its particular structure changes in response to different situations. Because families everywhere regulate sexual relationships, and because there are roughly as many men as women in most societies, it is hardly surprising that the most common form of marriage is monogamy, or marriage between one man and one woman. Societies with a shortage of eligible mates frequently also permit polygamy, or marriage to more than one partner.

Polygyny, the most common form of polygamy, is the marriage of one man to two or more women. The anthropologist George Murdock found that polygyny was permitted in 75 percent of the 565 mostly tribal societies he studied. Wives are generally a sign of wealth, which brings a man prestige in the community; more wives also produce more children, who provide extra labor. The hard economic fact that additional wives and children cost more to support, however, usually limits polygyny to a wealthy elite, like the sultans of the Ottoman Empire.

Polyandry, the marriage of one woman to more than one man, occurs only under unusually severe economic conditions. The most frequent type of polyandry is the sharing of a wife by brothers who are too poor to support separate households.