Are Humans Hard-Wired for Infidelity? The Evolutionary Science Behind Cheating
Monogamy is often upheld as a societal ideal, but evolutionary forces suggest a more complex reality. As an evolutionary biologist studying sex and relationships, I observe a fascinating contradiction: humans form deep romantic commitments, yet infidelity remains a common challenge that tests or breaks partnerships. This duality isn't merely a modern issue; it stems from ancient evolutionary pressures that shaped our species.
The Dual Drives: Bonding Versus Novelty
Research indicates humans have evolved two key urges: a drive for secure romantic bonds and a separate appetite for sexual novelty. These impulses, though often at cross-purposes, coexist in modern individuals. While many seek stable pair-bonds, others are more inclined toward variety, reflecting a spectrum of behaviours rooted in our ancestral past.
Genetic Predispositions to Infidelity
In 2010, a groundbreaking study I co-authored uncovered a genetic link to infidelity. By analysing DNA and behavioural surveys from young adults, we found that individuals with the "long" version of the dopamine D4 receptor gene were 50% more likely to report infidelity and engage in it multiple times. Dopamine influences excitement and risk-taking, associating this genetic variant with thrill-seeking behaviours like alcohol abuse and gambling.
However, biology isn't destiny. Genetics is just one factor among many, including environment and personal choice. Not everyone with this "infidelity gene" will cheat, but it suggests evolution favoured a diversity of traits, with some ancestors more predisposed to sensation-seeking and sexual novelty.
Evolutionary Adaptation and Population Diversity
From an evolutionary perspective, infidelity can be seen as an adaptation that may have promoted reproductive success. In any population, having a mix of risk-takers and cautious individuals can be beneficial. For example, in fish species, bold individuals access more resources in risky shallows, while shy ones stay safe in deep waters. Similarly, human forebears who strayed might have produced more or genetically diverse offspring, enhancing survival odds.
Yet, I hesitate to label humans as "hard-wired" for infidelity. Instead, we inherited a potential for sexual novelty, balanced by an equally powerful drive for committed pair-bonds. Many species exhibit "mate guarding," where animals aggressively protect their partners from interlopers, highlighting the adaptive value of fidelity in securing relationships.
The Modern Challenge: Balancing Drives in Relationships
Infidelity, defined by non-consensual betrayal, can erode trust and devastate relationships, threatening the very pair-bonds we evolved to cherish. The key question isn't whether we're destined to cheat, but how we manage these conflicting drives in long-term partnerships. Can the human appetite for novelty be expressed healthily?
I believe so. For some, this might involve open relationships, while others integrate novelty into existing bonds through shared experiences. Research on long-term passion shows that couples maintaining sexual satisfaction often engage in intimacy-building activities, such as romantic getaways, date nights, or exploring fantasies together.
These behaviours foster connection by demonstrating trust, vulnerability, and attachment. Experimenting together can reignite passion and strengthen bonds, emphasising that the power lies in mutual commitment to advancing intimacy.
Conclusion: Navigating Our Evolutionary Legacy
Humans aren't inherently programmed for infidelity, but we carry evolutionary legacies of both bonding and novelty-seeking. Understanding these drives can help us navigate modern relationships with greater empathy and creativity. By fostering open communication and shared exploration, couples can honour their biological heritage while building resilient, trusting partnerships.
Dr Justin Garcia is executive director of the Kinsey Institute and author of The Intimate Animal: The Science of Love, Fidelity and Connection.
