Figure 11.14 Customers peruse goods in a market in downtown Lima, Peru. Some Indigenous people in Peru begin marriage with a practice known as servinakuy. In servinakuy, a couple establish an independent household and live together until the birth of their first child, after which they are formally considered to be a fully married couple. (credit: “Lima, Peru” by YoTuT/flickr, CC BY 2.0) Marriage is the formation of a socially recognized union. Depending on the society, it may be a union between a man and a woman, between any two adults (regardless of their gender), or between multiple spouses in polygamous societies. Marriages are most commonly established to provide a formal structure in which to raise and nurture offspring (whether biological or adopted/fostered), but not all marriages involve reproduction, and marriage can serve multiple functions. One function is to create alliances between individuals, families, and sometimes larger social networks. These alliances may provide political and economic advantages. While there are variations of marriage, the institution itself, with a few notable exceptions, is universal across cultures. Marriage is an effective means of addressing several common challenges within families. It provides a structure in which to produce, raise, and nurture offspring. It reduces competition among and between males and females. And it creates a stable, long-term socioeconomic household in which the family unit can more adequately subsist with shared labor and resources. All societies practice rules of marriage that determine what groups an individual should marry into (called endogamy rules) and which groups are considered off limits and not appropriate for marriage partners (called exogamy rules). These rules are behavioral norms in a society. For example, in the United States, individuals tend to marry within the same generation (endogamy) and usually the same linguistic group, but they marry outside of very close kin (exogamy). Those considered to be too closely related to marry are prohibited by rules of incest, a relationship defined as too close for sexual relations. Across all cultures, there is an incest taboo, a cultural norm that prohibits sexual relations between parents and their offspring. This taboo sometimes extends to other relations considered too close for sexual relationship. In some societies, this taboo may extend to first cousins. In the United States, first-cousin marriage laws vary across states (see “Cousin Marriage Law in the United States” for current state laws). French anthropologist Claude Lévi-Strauss argued that incest is the original social structure because it naturally separates groups of people into two types—those with whom an individual has family ties (so-called biological ties) and those with whom an individual can have sexual relations and establish ties. Defining marriage can be complex. In the southern Andes of Peru and Bolivia, Indigenous people begin marriage with a practice known as servinakuy (with spelling variations). In servinakuy, a man and woman establish their own independent household with very little formal social acknowledgement and live together until the birth of their first child, after which they are formally considered to be a fully married couple. Not a trial marriage and not considered informal cohabitation, servinakuy is, instead, a prolonged marriage process during which family is created over time. Andean legal scholars argue that these unions should carry with them the legal rights and protections associated with a formal marriage from the time the couple begins living together (Ingar 2015). Like all social institutions, ideas about marriage can adapt and change. Within urban Western societies, the concept of marriage is undergoing a great deal of change as socioeconomic opportunities shift and new opportunities open up for women. In Iceland, in 2016, almost 70 percent of children were born outside of a marriage, usually to committed unmarried couples (Peng 2018). This trend is supported by national social policies that provide generous parental leave for both married individuals and those within a consensual union, but the change is also due to the more fluid nature of family today. As norms change in Iceland across generations, it will be interesting to see if the practiced form of consensual union we see today eventually comes to be considered a sanctioned form of marriage.