From an early age, we are socially conditioned to believe that a successful relationship involves two people engaged in a monogamous pairing. But recent research points to flawed assumptions about our inherent tendency toward monogamy, and shows that, in fact, humans are not hardwired to pair up with the same partner forever.

“Monogamy is a standard that we all think is appropriate, and infidelity is uniformly condemned. Few people think it’s acceptable to have multiple partners in a committed relationship,” says Lucia O’Sullivan, psychology professor at the University of New Brunswick, and sexuality and relationships researcher. “But the amazing paradox about that are the high rates of infidelity.”

READ MORE: Taking a break from your relationship? Here are the dos and don’ts

In a 2015 study published in the Journal of Sex Research, O’Sullivan and study co-author Ashley Thompson found that 30 to 75 per cent of men and 20 to 68 per cent of women in the western world have experienced some sort of infidelity. (The reason the numbers are so broad is because people report infidelity differently: for some, it means sexual intercourse, for others it could be watching pornography or having a celebrity crush.) O’Sullivan says that when they looked at the numbers of infidelities committed through standard sexual intercourse, the rates were high.

Story continues below advertisement

The reason for this, evolutionary psychologists argue, is that we are not naturally inclined to practice monogamy. Just ask Scarlett Johansson, who admitted to Playboy in February that it’s “not natural to be a monogamous person.”

“For men, the underlying evolutionary calculus of polygamy is clear: the possibility for a larger number of offspring and thus enhanced evolutionary fitness,” David Barash, an evolutionary biologist and author of The Myth of Monogamy, wrote in Time. “For women, the reasoning is more nuanced: the possibility of better genes for their children, improved access to material resources and social advancement.”

By that rationale, Barash argues, a woman would be better off being the 20th wife of a wealthy man versus the only wife of a poor one.

So, how did we settle on this one-partner structure? That is as much a result of evolved critical thinking as it is a female-led demand, O’Sullivan explains. If spreading their seed and passing their gene representation to the next generation is the main goal of the male, it’s in his best interest to stick around and help ensure the survival of his offspring. And it’s important to him that that offspring is, in fact, his.

WATCH BELOW: Do we need to rethink modern relationships?

6:33 Do we need to rethink modern relationships? Do we need to rethink modern relationships?

“He’ll never really know this unless he can account for the woman’s every moment of time up to the pregnancy,” O’Sullivan says. And it’s a pursuit that became increasingly difficult as women gained more rights and freedoms. After all, it’s a lot easier to keep tabs on your woman when she’s at home all day slaving over a hot stove.

Story continues below advertisement

As women gained more power and were able to support themselves, there was a closer adherence to a monogamous standard because they had more room to make demands, O’Sullivan notes. However, that also coincides with women’s increased participation in infidelity, she says, which links back to her belief that “all the features that are common of apes are common of us; in the wild, you wouldn’t see much monogamy.”

There was more at play than just gender balance in the latter half of the 20th century that further pushed society in the direction of monogamy, says Terri Conley, associate professor of psychology at the University of Michigan.

“In the early 1970s, swinging and partner-swapping was popular, but with the onset of the AIDS crisis in the ’80s, it seemed reckless to have sex with more than one person,” she says. “Now that we’re seeing that HIV is no longer a terminal disease for those who have access to health care, people again feel like they can question the idea that monogamy is the best scenario.”

In a study published in Perspectives on Psychological Science in March, Conley and her colleagues discovered that jealousy was more rampant in monogamous relationships than it was in consensual non-monogamous ones.

The study surveyed 2,124 people aged 25 and older in monogamous and consensual non-monogamous heterosexual relationships on elements like trust, satisfaction, commitment, jealousy and passionate love. In all categories but jealousy, there were no notable differences in the overall satisfaction of the two groups.

Story continues below advertisement

READ MORE: Being attractive could actually put your relationship in jeopardy

“The basic finding is if you take out the threat of cheating, people have less reason to be jealous,” Conley explains. “That’s important because there’s always been this perception that consensual non-monogamous relationships don’t work because of jealousy.”

It begs the question: is monogamy realistic? For Robin Rinaldi, journalist and author of The Wild Oats Project: One Woman’s Midlife Quest for Passion at Any Cost, it was a question she needed to take time to answer. (That time was a year of being in an open relationship with her then-husband.)

“I think monogamy is realistic as long as you know there might be slip-ups along the way,” she says. “Some people call this kind of monogamy ‘monogamish.’ It’s mostly monogamous but with a realistic version that admits that over the course of 50 years of marriage, things happen. It doesn’t mean you have a bad marriage.”

While Conley agrees that traditional monogamy may not be a knee-jerk response in humans — “if we’re hardwired to be monogamous, why do we have to put all these restrictions on people not to cheat?” she asks — she’s reluctant to chalk up our philandering ways to “natural” instincts.

“We as a society have already decided that plenty of things that are ‘natural’ should be eradicated,” she says. “Take cancer. We stamp it out because people die from it, but it naturally occurs in the body. Then there’s the argument that men are predestined to commit rape because they need to get their genetic materials to the next generation. That’s ‘natural,’ but it’s not good for society.” Tweet This

Story continues below advertisement

At the end of the day, however, most humans choose to couple off with one exclusive partner — a tendency that Barash says makes us “special” vis-à-vis our animal ancestors because what we’re doing is socially, rather than genetically, imposed.

READ MORE: Meet ‘Smarttress’: The mattress that will tell you if you’re being cheated on

We also can’t discount the main characteristic that separates us from animals: rational thought.

“Partnering for love reinforces the ideal of monogamy,” says Kasey Lafferty, registered psychotherapist at KMA Therapy. “There’s an obvious stigma around people who cheat and betray their monogamous relationship. And the more it’s discussed in the celebrity world, on television and in movies, the more the conversation revolves around the hurt and trauma it causes. That further reinforces monogamy.”

O’Sullivan says the way to mitigate the possible hurt and trauma is to have an open discussion about what monogamy means and what its parameters are within a relationship.

“Monogamy is usually non-consensual. The couple doesn’t agree to it,” she says. “Some people suggest if we were more honest with our partners about our interest in other people or what our exchanges with them entail, we’d have stronger partnerships. Because for so many people, a strain of any form is a deal-breaker.”