Monogamia

Monogamy is a mating system in which an individual forms a long-term exclusive relationship with a single partner. It is often distinguished as social monogamy, where two individuals form a bonded pair and cooperate in mating and parental care, and genetic (or sexual) monogamy, where mating exclusivity is observed and offspring are sired by that partner. In practice, many species exhibit social monogamy without strict genetic monogamy, and some human patterns involve serial monogamy rather than lifelong exclusivity.

In humans, monogamy is common but culturally variable. Many societies emphasize lifelong monogamous marriage, while others feature serial monogamy, varying expectations of fidelity, or form unions outside traditional marriage. Legal, religious, economic, and social factors shape patterns of partnership. Non-monogamous arrangements exist in many cultures, and contemporary contexts increasingly recognize same-sex and other nontraditional forms of monogamy as legitimate relationships.

In the animal kingdom, monogamy occurs across a range of taxa, particularly among birds, where social bonds and shared parental duties are common. In mammals, true genetic monogamy is relatively rare, though many species form long-lasting pair bonds that involve cooperative care and territorial defense, sometimes accompanied by extra-pair mating that complicates paternity.

Evolutionary explanations for monogamy emphasize parental cooperation, reduced competition for mates, and ecological factors that make pair-based offspring rearing advantageous. Costs include limited genetic diversity and potential vulnerability if a partner fails to cooperate. Research continues into the behavioral, genetic, and neural bases of monogamous bonds, including the roles of hormones such as oxytocin and vasopressin in pair bonding.