To poet John Dryden, jealousy is the jaundice of the soul. For poet and activist Maya Angelou, it’s like salt: a little can enhance the flavour but too much can spoil the pleasure. Anthropologist Margaret Mead called it the barometer of a lover’s insecurity. German philosopher Friedrich Nietzsche described it as a scorpion turning its poisoned sting against itself. There’s even a Greek god of jealousy — Phthonos — who accompanied the goddess of love Aphrodite. His female counterpart was Nemesis, she of jealous retribution.
But to most of us, jealousy is just a midnight Facebook creep, or a twinge when we run into an ex on a date, or the mild thrill of watching a co-worker flirt with our partner at the office Christmas party. It’s often part of dating.
Biological anthropologist Helen Fisher, senior research fellow at the Kinsey Institute in Indiana, sees an evolutionary reason in most of love’s manifestations. In her book Anatomy of Love: A Natural History of Mating, Marriage, and Why We Stray, Fisher describes “this intense human affliction” as “a combination of possessiveness and suspicion of a partner.”
“It’s so powerful and primordial,” Fisher says. “It’s probably an evolutionary adaptation to protect your resources.”
“I’m convinced jealousy is biologically based. You certainly see it in every culture anthropologists have (studied).” (Hence Mead’s poetic description.)
Jealousy is considered a “complex” emotion, as opposed to more primary emotions love and fear. The first MRI study on the neural correlates of jealousy was conducted in 2006 and showed different brain activity in men and women who were presented with jealousy-arousing sentences in a lab, such as “my boyfriend telephones his ex-girlfriend every day” or “my girlfriend took an overnight trip with another man.”
Men showed greater activation in the amygdala and hypothalamus, which are associated with processing basic emotions and with reproductive and aggressive behaviour. Women showed greater activation in the cortical regions and the part of the brain associated with deciphering trustworthiness and deception.
A 2016 study in Scientific Reports, an open-access part of the journal Nature, investigated whether the level of jealousy changed over time. It found that jealousy increased as a relationship solidified, according to brain scans of romantic partners at different stages.
Greater romantic happiness was correlated with greater jealousy. Activity in the basal ganglia, a deep-brain structure associated with emotional processing and executive function, was more notable in response to jealousy-inducing scenarios after a relationship was established. Emotional intensity was linked to romantic happiness, measured by activity in part of the prefrontal cortex.
Jealousy, or what’s known as “mate-guarding” has been demonstrated in various species.
Dogs are known to snap at their owner or rival when their owner shows affection to another dog. Female apes will drive other females from family territory. Male bluebirds have been shown to pull the tail feathers from their mates and attack other males who come too close to the nest. A 2017 study in Frontiers in Ecology and Evolution showed male coppery titi monkeys, which are monogamous, would physically try to hold a mate back if a male rival was nearby. The jealous monkeys showed elevated levels of testosterone and cortisol, and activity in the part of the brain associated with social pain in humans known as the cingulate cortex.
“I’ve never seen a fish be jealous, but I wouldn’t be surprised if they do some mate-guarding,” Fisher says.
While mate-guarding can be harmless, it can also be dangerous. Studies have shown more men than women turn to violence when they feel betrayed, and jealousy is a cause of spousal homicide.
Jealousy is triggered in a variety of social contexts, not just romantic, though it’s nearly universal to lovers. A cluster of brain processes may be at work, depending on personality type.
“You lie wide awake when you’re jealous. You don’t fall asleep when you’re jealous. And you’re certainly very anxious,” Fisher says. That means brain regions linked to stimulants such as dopamine, epinephrine will likely be activated, as well as stress hormone cortisol. How an individual person reacts could involve testosterone, which is associated with aggression, or estrogen if jealousy results in a tearful breakdown or trying to talk it out, Fisher says.
It’s hard to tell in the moment whether jealousy stems from insecurity, as most experts will say, or whether the feeling is a normal reaction to some kind of misbehaviour.
Danny Fong, 29, says he had been jealous most of his life.
Just hearing another guy was interested in his first girlfriend made him feel he had to prove his worth. Jealousy came in the form of fears — fear of abandonment, fear of not being good enough. With his current girlfriend, he has “unlearned” jealousy.
Fong attributes his recent epiphany to reading a book about personality types known as , as well as a particularly frank conversation with his girlfriend in which they overcame some perceived barriers to vulnerability.
“Being emotionally conscious and available is the solution to most of the problems that cause anxiety in our heads,” says Fong, a musician and a cappella performer. “Unlearning happens when you take a step back from your own thoughts.”
Not everyone is so enlightened, but jealousy is something polyamorous people also deal with up front.
“It’s the biggest hurdle for everyone,” says Sasha O’Marra, who has had both a girlfriend and a boyfriend for the past year. One is married and one sees other people. “It’s such a common human emotion … it’s so easy to slip into.”
Accepting her girlfriend was married was somewhat easier than working through the jealousy of her boyfriend dating other people, she says. To her, jealousy feels like a “hot, sick, tingly feeling, like when you find something out you’re not supposed to know.”
That leads to comparisons to other people, which often can lead to self-pity and self-criticism, says O’Marra, 24, an advertising student at Humber College.
“Eventually, I went, ‘You know what? Me being upset with this isn’t going to change it. And I don’t really have the right to be upset about this.” Now, she gets along with her girlfriend’s wife.
Some, though not all, poly relationships have a hierarchy with a primary partner, especially if there are children in the family. Some keep their relationships strictly separate, but some are more open to spending time together and are even friends.
This generosity and drive to ward off jealousy is known as compersion — defined as the feeling of joy associated with seeing a loved one feel joy, even with another lover — in polyamorous relationships. It involves a ton of communication and setting boundaries. Cheating is not infidelity but breaking the rules.
It’s something monogamous couples can learn from.
“In conventional dynamics we assume if your partner looks at someone else, that shows a lack of love for you, but in poly it doesn’t have to,” says Jilian Deri, a sociologist who wrote her PhD dissertation on jealousy and compersion in queer women’s polyamorous relationships.
And poly people strive to examine the jealous feeling for what’s beneath the immediate reaction.
“That’s often the way you crack it,” Deri says. “In a poly dynamic if you’re continually jealous, you’re going to be miserable, so it’s something you have to rework.”
The Science of Dating is an occasional series exploring the great experiment that is love and the human condition.