It Turns Out Dolphins Are Gay and Not Just in a Happy Way

Same-sex relationships aren't just a human phenomenon. From lifelong social bonds to sexual behavior between males, dolphins have a fascinatingly queer side that scientists have been studying for decades.

Dolphins are known for their intelligence, playful nature, and complex social systems. But there's another side of dolphin behavior that doesn't get nearly as much attention: dolphins are remarkably sexually social animals, and a significant part of that social activity happens between members of the same sex.

In fact, researchers have documented male dolphins engaging in sexual behaviors with one another, developing close relationships, and forming alliances that can last for decades. So like, are dolphins queer? Sexuality is a human concept, and labeling a species of animals with it would be anthropomorphizing, but all the research shows that sexual diversity isn't something humans invented. 

Despite what some people might believe, same-sex sexual behavior isn't exclusive to humans. Scientists have documented it in more than 1,500 animal species, including mammals, birds, reptiles, insects, and marine animals. These behaviors can include courtship, mounting, genital contact, and even long-term pair bonding. Researchers typically refer to these interactions as same-sex sexual behavior or same-sex socio-sexual behavior, particularly when sexual activity occurs in a social context rather than for reproduction.

For years, scientists struggled to explain why animals would participate in sexual behaviors that don't directly produce offspring. Traditional evolutionary theories often emphasized reproduction as the primary purpose of sex, which made same-sex interactions appear puzzling. But sexual behavior can serve purposes beyond reproduction, including establishing social relationships, reducing conflict, and maintaining alliances.

And dolphins use all of those tools in their social groups. 

Bottlenose dolphins are among the most extensively studied marine mammals when it comes to same-sex sexual behavior. Researchers have observed male dolphins mounting one another, engaging in genital contact, and using their flippers, snouts, and other body parts to stimulate another dolphin. These interactions can occur between pairs or in larger groups. Although same-sex behavior has also been documented among female dolphins, research has found it to be particularly prevalent among males.

One of the more striking examples comes from a 2015 master's thesis by researcher Natalia Botero Acosta at the University of Southern Mississippi. Acosta analyzed underwater video footage collected between 2010 and 2013 from a group of captive bottlenose dolphins at the Roatán Institute for Marine Sciences in Honduras. Across the study, researchers identified 1,872 male-male socio-sexual interactions during 195 sampling periods. The most common behavior was mounting, which accounted for approximately 61% of the recorded interactions. Other behaviors included genital touching using the snout or flippers.

While I'm not one to label someone else's sexuality, that does sound pretty gay. 

These weren't exclusively interactions between younger dolphins. Although juveniles participated most frequently, researchers observed same-sex sexual behavior across every age class. Dolphin same-sex behavior is a recognizable part of how these animals interact with one another.

So, why do dolphins have these kind of same-sex relationships? 

Scientists have proposed several explanations for why dolphins engage in same-sex sexual behavior, including establishing dominance, practicing future mating behaviors, reducing social tension, and strengthening relationships. While no single explanation accounts for every interaction, research suggests that social bonding is one of the most important functions of same-sex sexual behavior among male bottlenose dolphins.

Dolphins live in complex social societies where relationships can have important consequences for cooperation, survival, and reproduction. Male dolphins, in particular, are known to form alliances with other males. These partnerships can help them navigate conflicts, cooperate with one another, and gain access to potential female mates. Some male alliances remain stable for 20 years or longer.

Research on wild bottlenose dolphins in Shark Bay, Australia, has documented elaborate systems of male alliances, sometimes involving multiple levels of cooperation between groups. These relationships can begin when dolphins are young and continue well into adulthood.

Behavioral ecologist Janet Mann has spent decades studying dolphins and their social relationships. Her research has explored how male-male sexual interactions may contribute to the development of trust and alliances. Mann first observed two male dolphins, Cookie and Smokey, in the 1980s. The two formed an exceptionally close relationship involving sexual behavior, which reportedly continued for decades.

While we should be careful about describing animal relationships as human-style romantic partnerships, these observations demonstrate how significant male-male bonds can be in dolphin society.

Same-sex sexual interactions may help dolphins establish trust, evaluate potential partners, and maintain these important social bonds. Sexual behavior can be part of dolphin relationship-building... really leaning into "friends with benefits." 

One of the most interesting findings from Acosta's 2015 research involved reciprocity. Scientists wanted to understand whether same-sex sexual interactions were primarily expressions of dominance, where one dolphin consistently took the active role, or whether dolphins participated more equally.

Of the 22 male pairs analyzed for patterns of role exchange, only five demonstrated statistically significant asymmetry. The remaining pairs exhibited more reciprocal patterns, with dolphins taking turns in the different roles. If same-sex sexual behavior were primarily about establishing dominance, scientists would expect to see more consistently one-sided interactions. Instead, the findings suggest that many of these encounters involve mutual participation. Researchers believe this reciprocity may help dolphins develop trust and reinforce social relationships.

The study also found that dolphins had preferred companions for socio-sexual interactions, rather than choosing partners entirely at random. So while it's tempting to imagine dolphins casually swimming around having sex with everyone in sight, their actual social relationships appear to be considerably more nuanced. Some dolphins associate with particular individuals more frequently than others, and sexual behavior may be one way they maintain those connections.

Importantly, having a close sexual and social relationship with another male doesn't necessarily prevent a dolphin from reproducing with females. These different relationships can coexist.

Animal behavior is rarely as simple as one universal explanation, and we need to distinguish between animal behavior and human identity.

When scientists study dolphins, they can observe who engages in sexual activity with whom, how often these interactions occur, and what social functions those behaviors might serve. What researchers cannot do is ask a dolphin how it experiences attraction, romantic attachment, or sexual identity.

Terms like gay, lesbian, and bisexual describe human sexual orientations and identities that involve elements of attraction and personal experience. While researchers sometimes use terms such as homosexual or bisexual behavior when discussing animals, applying human identity labels directly to dolphins can oversimplify what we actually know. 

Same-sex sexual behavior is a well-documented, naturally occurring part of dolphin life and researchers have compelling evidence that these interactions can serve meaningful social functions beyond reproduction.

Human LGBTQ+ identities can't be directly explained by observing animals. Human sexuality involves biological, psychological, cultural, and social dimensions that can't be reduced to dolphin behavior. And queer people certainly don't need approval from the animal kingdom to justify their existence.

But the idea that same-sex behavior is inherently unnatural simply isn't consistent with what scientists have observed. Sexual diversity exists throughout the natural world, often in ways that challenge simplistic assumptions about relationships, reproduction, and behavior.

So the next time someone insists that homosexuality doesn't exist in nature, you can tell them to take it up with the dolphins.

Sources

Botero Acosta, N. (2015). Same-sex socio-sexual interactions among a group of captive bottlenose dolphins (Tursiops truncatus) [Master's thesis, University of Southern Mississippi]. The Aquila Digital Community. https://aquila.usm.edu/masters_theses/151/

Gionis, A. (2023, June 17). Diving into the deep: Unravelling same-sex socio-sexual behaviours in bottlenose dolphins (Tursiops truncatus). Sea Watch Foundation. https://www.seawatchfoundation.org.uk/diving-into-the-deep-unravelling-same-sex-socio-sexual-behaviours-in-bottlenose-dolphins-tursiops-truncatus/

Paul, J. (2025, May 8). Dolphins, like all bisexuals, are misunderstood. Bi.org. https://bi.org/

Mann, J. (2006). Establishing trust: Socio-sexual behaviour and the development of male-male bonds among Indian Ocean bottlenose dolphins. In V. Sommer & P. L. Vasey (Eds.), Homosexual behaviour in animals: An evolutionary perspective (pp. 107–130). Cambridge University Press.

Monk, J. D., Giglio, E., Kamath, A., Lambert, M. R., & McDonough, C. E. (2019). An alternative hypothesis for the evolution of same-sex sexual behaviour in animals. Nature Ecology & Evolution, 3, 1622–1631.