THE SCIENCE OF DATING
Researchers unlock the biological explanation for Selena and the Weeknd’s matching footwear, Kimye’s conjoined name and the fact that after a while, two hearts really do beat as one,
This is part of an occasional series breaking down the science behind the mysterious condition known as love.
It’s why Kimye — or Kim Kardashian and Kanye West, for the uninitiated — are now “officially just one person,” according to BET.
It’s why Selena Gomez and The Weeknd post photos of their matching outfits to Instagram and why Justin Timberlake and Britney Spears stepped out in matching denim atrocities, including a denim cowboy hat, at the 2001American Music Awards.
But this couple convergence isn’t just for celebrities. After a while, many couples start to seem distractingly similar and start saying “we” all the time, as though they’ve merged into one. Science shows that after a while, two actually do become one — psychologically and even microbiologically.
In psychology, the idea of “inclusion of (the) other in the self” is a foundational concept introduced in 1992 by American social psychologist Arthur Aron. This is represented in a scale with a series of overlapping circles used to indicate how psychically enmeshed a research subject felt with his or her partner. The scale has since been used in hundreds of studies.
“Your cognitive, mental, brain structure of who you are is actually partly overlapping with who this other person is,” Aron says. Hence the circles.
But this represents more than a whimsical notion. Functional MRI scans have shown that when subjects think about a “close other,” the same parts of the brain are activated as when they think about themselves, he says.
“It’s the sense we mix ourselves up with the other person,” says Aron, based at Stony Brook University in New York. “They’re part of us. If something good happens to them, we feel good. If something bad happens, we feel bad. If they see something, we think we saw it.”
This is, in part, a way to explain the process of intimacy in close relationships. Aron knows close relationships: He is perhaps best known for the famous “36 questions to fall in love” questionnaire. That rubric was also developed in the ’90s but found a pop culture sequel when a Vancouver woman who successfully tried it wrote about her experience in a New York Times column that went viral in 2015.
Inclusion of the other in the self occurs over time and encourages longevity. But it emerges most intensely with a new relationship.
With the formation of a new relationship, you’re actually becoming a new person, says social psychologist Geoff MacDonald, who runs an eponymous research lab at the University of Toronto.
“Literally, at the cognitive level, what you’re starting to do is — in a small way at first, which becomes greater if you’ve known the person for a long time — start to merge yourself with that person. You kind of confuse which one of you is which.”
This novelty is, in part, what makes the early stages so thrilling, MacDonald says. Eventually, couples start to experience what’s known as “cognitive distribution” and shared remembering. Studies have suggested couples “pool” their cognitive resources to use their partner’s memory as an extension of their own.
The loss of a relationship and therefore this shared memory system may contribute to a period of real confusion after a breakup.
Couples experience “emotional contagion” and even their physical health outcomes tend to merge over time.
“This occurs in part because of assortative mating: People typically choose a partner who is similar in terms of attitudes, demographics and health-related behaviours, such as diet, physical activity, smoking and alcohol consumption,” states a 2017 report in the Annual Review of Clinical Psychology.
But “spouses’ daily life activities are intertwined, and each partner’s personal attributes — mood, attitudes, behaviour, health, stresses and lifestyle — affect both spouses.”
Assortative mating, a form of sexual selection in which couples choose mates they resemble in some way, may explain why so many couples seem to look alike. A more romantic study from the 1980s showed that years of shared emotions led some older couples to develop distinctly matching patterns of wrinkles, leading them to look more similar than when they first got together.
Couples also start to blend on a microbiological level. This summer, scientists at the University of Waterloo published their findings that couples who cohabitate share even the tiny organisms known as microbiota that live on their bodies. A research team led by microbial ecologist Josh Neufeld analyzed bacteria from the skin of10 sexually active couples who lived together.
A computer algorithm was able to detect romantic partners 86 per cent of the time based on the composition of their microbiota, especially in samples obtained from feet.
Samples from the torso, navel and eyelid also matched more often than would be predicted by chance alone. Other factors include lifestyle, skin condition, hygiene, pets and allergies, but cohabitation was more predictive. Only biological sex and individual markers left clearer indications of whose microbiota belonged to whom.
Neufeld hypothesized the transfer was made through skin contact and the home environment, such as touching the same computer when settling in for a night of Netflix. (The eyelids thing remains a mystery.)
According to the study, published in open-source microbiology journal mSystems in June, humans shed more than one million biological particles per hour. No wonder some join forces. But for Neufeld, showing couples share some microorganisms isn’t the ultimate takeaway from this research. He’s interested in the unique microbial composition of each human and how their microbiota adapt to each host environment — which organisms are where and when and what it means.
“Why do people kiss in the first place?” Neufeld says. “It’s certainly a vehicle for microbial exchange.”