For many individuals, the institution of marriage has never solely revolved around having one sexual partner. In much of the Western world, monogamy is perceived as the appropriate and natural arrangement for human relationships. In fact, a survey conducted in 2000 found that approximately 95% of cohabiting and married adults in the U.S. anticipated monogamy from their partners, believing their partners held the same expectation. However, a broader examination reveals that social monogamy and sexual fidelity often diverge significantly in various cultures. While human pair bonding has roots in ancient times, the expectation of sexual exclusivity is a relatively recent development.

Interestingly, many individuals who claim to support monogamy still engage in extramarital affairs, with estimates suggesting that between 20% to 60% of Americans do so, depending on the source. Furthermore, numerous cultures do not regard sexual exclusivity as essential, despite having some form of marital structure. Some studies indicate that as many as 83% of societies do not adhere to monogamous norms.

This raises the question of whether our emphasis on monogamy stems from cultural conditioning rather than biological imperatives. In fact, many animal species demonstrate that strict sexual exclusivity is not the norm. For instance, while around 90% of bird species are socially monogamous, research has revealed that in certain species, up to 75% of young result from "extra-pair copulations." This suggests that female birds often mate with multiple males, increasing genetic diversity among their offspring.

The argument extends to human anatomy as well; the coronal ridge of the human penis appears designed to displace semen from previous males, hinting at a natural inclination toward sperm competition rather than mere mate guarding. Moreover, research indicates that female reproductive tracts may evaluate potential mates chemically after copulation, essentially determining genetic compatibility based on internal criteria rather than external traits.

Bernard Chapais from the University of Montreal noted in a recent Evolutionary Anthropology review that the human mating system is remarkably adaptable, with only 17% of cultures being strictly monogamous. Most societies exhibit a blend of marriage styles, with many individuals practicing monogamy alongside others in polygamous relationships.

However, socially monogamous marriages do not inherently demand sexual fidelity. For example, among the Warao people of Brazil, marriages can be temporarily suspended for ritual relationships, allowing individuals to engage in sexual activities freely, which are regarded as honorable and beneficial for offspring. Similarly, the Na (or Mosuo) of China have "walking marriages," where relationships are fleeting and autonomy is highly valued, with possessiveness viewed negatively.

Our Paleolithic ancestors seemed to grasp the social significance of mating with individuals from other groups, as well as the necessity of preventing inbreeding. Professor Martin Sikora from the Centre for GeoGenetics at the University of Copenhagen suggested that these early humans likely facilitated exchanges between groups to maintain genetic diversity, indicating a strategic approach to social structure.

Marriage has long been a fundamental aspect of human kinship and social organization, with reciprocal exogamy and mate exchange forming the basis of alliances between groups. Thus, pair bonding serves functions beyond the nuclear family, and like many bird species, cohabitation does not necessarily imply sexual exclusivity.

The concept of partible paternity, where multiple men are recognized as fathers to a woman's child, persists in certain regions and fosters solidarity within communities, enhancing the welfare of children. It was not until the advent of agriculture and the patriarchal systems that followed that women's sexual autonomy faced restrictions, primarily to establish clear lineages for property inheritance.

Historically, it was predominantly women who faced societal pressure to remain sexually monogamous, while men often faced minimal stigma for infidelity. The mid-Victorian era marked a shift, as men were urged to suppress their instincts, with societal expectations tightening around both genders' sexual behaviors.

In contemporary society, many couples enter marriage without discussing their views on sexual fidelity, often assuming that cohabitation implies exclusivity. Yet, this assumption is not universal, and many cultures continue to embrace alternative relationship structures. Increasingly, individuals are exploring "monogamish" lifestyles, where couples maintain emotional bonds while engaging with others sexually, or polyamorous arrangements that may include multiple partners without a primary focus.

Although polygyny has been practiced historically and continues in some cultures, the prevalence of monogamous pairings is more apparent in our ancestry. Evidence suggests that early marriages likely involved arrangements and reciprocal relationships, with brideprice or brideservice highlighting the negotiation between kin groups.

In conclusion, while pair bonding is an ancient human practice, the expectation of sexual fidelity is a modern construct. Couples choosing to prioritize exclusivity have every right to do so, but it is essential to recognize that this expectation is a cultural rather than a biological norm. In light of evolving relationships, many individuals are beginning to challenge traditional notions of marriage and fidelity, with more people embracing greater autonomy in their romantic lives.

In Brazil, a traditional Canela marriage ceremony emphasizes this notion of non-possessiveness, as the bride and groom are reminded to remain together without jealousy toward each other's partners.

Note: This discussion focuses on heterosexual pair bonding, as it has been more extensively studied over time and across cultures compared to homosexual relationships. However, it is acknowledged that many same-sex relationships also operate outside the confines of sexual exclusivity.

© Copyright Elle Beau 2020 Elle Beau writes on Medium about sex, life, relationships, society, anthropology, spirituality, and love. Unauthorized reproduction of this story is prohibited.