5 Scientific Reasons We Fall in Love

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As we approach the annual celebration of love known as Valentine’s Day, perhaps we should more specifically celebrate the science behind love. Because, as unsexy as it sounds, research overwhelmingly supports the fact that we often don’t choose the person we fall in love with; the characteristics we find ourselves attracted to in our mates are encoded in our DNA before we are born. Below are some key factors that researchers use to explain how and why Cupid’s arrow strikes.


5. Hormones Drive Love (and Lust)

Several powerful hormones affect our attraction to other people.

© Andrey Mindryukov

Hormones are such players in the chemistry behind attraction that Dr. Helen Fisher, one of the best-known contemporary researchers on the topic, has assigned different hormones to each of the three stages of human attraction: lust, romantic love and long-term attachment. That initial sexual attraction you feel before you even know a person’s name is driven by testosterone and oestrogen and, before you think testosterone only drives male sexual appetite, Fisher claims women also have testosterone to blame for that lusty feeling. As Fisher puts it, these hormones, “get you out looking for anything.” We’re not exactly choosy, apparently, at this stage. We have a group of three neurotransmitters to blame for the next “choosier” stage, attraction, or the romantic love celebrated in all those William Blake sonnets. The same feel-good chemical, dopamine, released after we imbibe on our favorite adult beverage also floods us with a “high” of sorts when we’re in that butterflies stage with our loved one.

We have norepinephrine (aka adrenalin) to thank for those sweaty palms, flushed cheeks and racing heartbeat so associated with first love or new love, and a depletion in serotonin is to blame for all the crazy things that love makes us do — from daydreaming when we should be working to barely eating for days on end. Finally, long after the butterflies and daydreams have subsided, oxytocin and vasopressin — two chemicals released by the nervous system and linked to social attachment — take hold, contributing to the long-term commitments that result in marriage and children.


4. Opposites Attract … But Why?

There are scientific reasons that opposites attract.

© Prayitno

We’ve all heard that “opposites attract,” but there is science to support we can’t help ourselves; that attraction is in our genes. Specifically, we need to look no further than a series of genes unique to each of us, MHC proteins, which play a critical role in regulating immune response. Researchers with the University of Parana in southern Brazil contend that, while one might initially cite all the similarities that make his or her mate “ideal,” science suggests that it’s the differences that are really responsible for our subconscious attraction to a mate. And it all comes down to base biology. We may not realize it, but we’re drawn to individuals who will produce the healthiest offspring. Think, for a moment, of the conditions and illnesses so often associated through history with “keeping it in the family,” such as the neurologic condition porphyria (thought to have contributed to King George III’s madness), and the blood disease hemophilia among intermarrying royals. By subconsciously being drawn to those individuals who are unlike us, we avoid the disorders associated with inbreeding. Those Brazilian researchers also noted a link between how well the immune system works and what’s called “genetic variability” — those differences, as opposed to similarities, among us.


3. Great Symmetrical Features Attract Mates

Studies have shown that men and women are drawn to mates with good symmetrical features.

© Wirawat Lian udom

Much has been made about how we unknowingly gravitate toward individuals who have symmetrical features. We need only look to the sheer number of models and other “beautiful people” — both men and women — who bear the same characteristic facial and body symmetry. But what are the biological reasons behind our attraction to these “perfect” features? It all starts at conception. Ideally, the developing body would consist of cells that divide perfectly each and every time and produce a babe whose left and right sides mirror each other — in perfect symmetry. But mutating genes and environmental pressures get in the way and we end up with less than perfect symmetry and, importantly, these variables often contribute to health problems with long-term implications. So, again, those individuals with symmetry, in face and physique, are prized notably for their association with being robust and fertile, boasting the ability to produce strong and healthy offspring.

In terms of symmetry, men’s eyes are generally drawn to women with smaller chins, jaws and brows and, accordingly, more prominent eyes. Ladies are typically drawn to men with strong jawlines and chins, and a more prominent brow ridge. While studies have shown that men carrying a little weight around the middle aren’t as prized as those sporting a six-pack (obviously), the preference for symmetry on this front appears to be less pronounced in women who also take into account the features that aren’t as tangible from the outset (from sense of humor to educational attainment and social status). On the other hand, research has found that men are most attracted to women with a waist-to-hip measurement ratio of 0.7. No surprise here that this shape is associated not only with a healthier person, free of diseases like Type 2 diabetes, but with a healthier potential mother — capable of producing healthy children.


2. Pheromones: Real or Make Believe?

Pheremones do exist in the animal kingdom, but researchers disagree on their existence in humans.

© J.L. Stricklin

Research into these chemicals and their link to attraction across the animal kingdom is not new; however, it has become increasingly controversial, thanks to the emergence of pheromone sprays and drugs that many scientists proclaim as “quackery.” That said, pheromones are best understood in other animals, particularly rodents that possess what’s called a “vomeronasal organ” in their nose that can pick up on these chemicals in other rats’ urine and use this sense as the guide to identifying the gender of other rats and selecting mates. It appears the only real certainty when it comes to humans and pheromones is that this connection is not well understood. While researchers going as far back as the 1980s found evidence that such an organ could exist in most adult humans, again, this remains controversial. That said, pheromone “believers” note that, in humans, the chemical can be found in sweat. In 2006, for example, scientists at the University of New Mexico somehow enlisted female volunteers who took a big whiff of men’s sweaty T-shirts. The researchers found that women were attracted to men who, of all things, happened to have symmetrical faces — though they couldn’t see those faces but could apparently smell that they were great-looking specimens!

It’s believed the body can communicate its “reproductive quality” to a potential mate through pheromones. In similar tests, where the roles were reversed and men smelled women’s sweaty garments, comparable findings were discovered, with men being most attracted to women during the time of the month when women were most fertile. Once again, it appears that pheromones struck, with women sending out signals to men via their sweaty garments that they’re healthy and able to pass their genes on to the next generation.


1. Women Seek a Provider, Men Want a Nurturer

Studies have shown that women often look for a man who can provide financial security in a relationship.

© Michael S.

Many of these factors seem to support the notion that even the most independent among us are using the same key characteristics in selecting our mates, and we just can’t help ourselves. Be it through a jaw that could shred a carrot or an attraction to the ability to hold a steady job, researchers contend that women are subconsciously looking for a provider who, going back to the “caveman days,” could hunt food and offer protection to the brood. Be it through a youthful face or a whittled middle capable of producing healthy kids, men are subconsciously on the hunt for females who are child-bearers and nurturers. It all seems so base — that we’re all merely looking for a reproduction partner. But evolutionary biologists and anthropologists insist, in a lot of respects, we’re no different than other creatures on this planet. Only, instead of fanning gorgeous feathers like a peacock or puffing out the cheeks and growling like a baboon, we “sophisticated” humans attract mates by compulsively flipping our hair or walking with an over-exaggerated hitch in our step. Kind of makes you wonder who’s really the most evolved species here.


One More: Men and Women Attracted to Big Pupils

The women of Medieval Europe were on to something when they added a few drops of a solution culled from the belladonna plant to dilate their pupils as a means of attracting the opposite sex with their dreamy, bedroom eyes. In fact, “belladonna” itself literally means “beautiful lady” in Italian. Of course, the use of belladonna did have adverse impacts (from heart problems to blindness) but, hey, at least our big-eyed ladies got their men! There is something to be said for the lengths our forerunners would go to increase, of all things, their pupil size, as researchers have found that men consistently gravitated toward the photographs of women with enlarged pupils over photos featuring the same women, only with smaller pupils. It goes both ways, ladies, as researchers at Edinburgh University found women were attracted to men with big pupils, with the attraction to this feature peaking during the time of the month when the survey’s subjects were most fertile. Also, studies have shown that pupils naturally dilate when we’re excited about something. So, if you see something (or someone) that you like, it’s as if your eyes can’t get enough of them. It should also be noted that pupils dilate in low-light conditions and when drink is added to the mix — dilated eyes galore at that nightclub.


Written by

Michelle Leach's love of writing has taken her to Sydney, Australia, London, U.K. and other exotic locations like Grand Island, Neb., and Clio, Mich. She has developed pieces for TV and radio stations, PR departments, newspapers and magazines. A graduate of Northwestern University and Lake Forest College (also in Illinois) she enjoys running marathons and likes to say when not writing, she’s running — but she tries not to mix the two activities.