When You Feel "Chemistry" With Someone, What's Actually Going On?

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We know chemistry when we feel it with another person, but we don't always know why we're drawn to one person over another. Is it just a cascade of neurotransmitters and hormones conspiring to rush you toward reproduction? Is it attraction borne of a set of shared values? Or is it bonding over specific experiences that create intimacy?

It's probably a combination of all three, plus ineffable qualities that even matchmaking services can't perfectly nail down.

"Scientists now assume, with very few exceptions, that any behavior has features of both genetics and history. It's nature and nurture," Nicole Prause, a sexual psychophysiologist and neuroscientist, tells Mental Floss. She is the founder of Liberos, a Los Angeles-based independent research center that works in collaboration with the University of Georgia and the University of Pittsburgh to study human sexual behavior and develop sexuality-related biotechnology.

Scientists who study attraction take into consideration everything from genetics, psychology, and family history to traumas, which have been shown to impact a person's ability to bond or feel desire.

THE (BRAIN) CHEMISTRY OF LOVE

Helen Fisher, a biological anthropologist at Rutgers University, Match.com's science advisor, and the author of Anatomy of Love: A Natural History of Mating, Marriage, and Why We Stray, breaks down "love" into three distinct stages: lust, attraction, and attachment. In each stage, your body chemistry behaves differently. It turns out that "chemistry" is, at least in part, actual chemistry. Biochemistry, specifically.

In the lust and attraction phases, your body is directing the show, as people can feel desire without knowing anything personal about the object of that desire. Lust, Fisher asserts in a seminal 1997 paper [PDF], is nothing more than the existence of a sex drive, or "the craving for sexual gratification," she writes. It's a sensation driven by estrogens and androgens, the female and male sex hormones, based in the biological drive to reproduce.

Attraction may be influenced less than lust by physiological factors—the appeal of someone's features, or the way they make you laugh—but your body is still calling the shots at this stage, pumping you full of the hormones cortisol, adrenaline, and dopamine, effecting your brain in a way that's not unlike the way illicit substances do.

Fisher has collaborated multiple times on the science of attraction with social psychologist Arthur Aron, a research professor at Stony Brook University in New York. Aron and his wife Elaine, who is also a psychologist, are known for studying what makes relationships begin—and last.

In a 2016 study in Frontiers in Psychology, the researchers proposed that "romantic love is a natural (and often positive) addiction that evolved from mammalian antecedents by 4 million years ago as a survival mechanism to encourage hominin pair-bonding and reproduction, seen cross-culturally today."

In the attraction phase, your body produces increased amounts of dopamine, the feel-good chemical that is also responsible for pain relief. Using fMRI brain imaging, Aron's studies have shown that "if you're thinking about a person you're intensely in love with, your brain activates the dopamine reward system, which is the same system that responds to cocaine," he tells Mental Floss.

Earlier, Fisher's 1997 paper found that new couples often show "increased energy, less need for sleep or food, focused attention and exquisite delight in smallest details of this novel relationship."

The attachment phase is characterized by increases in oxytocin and vasopressin; these hormones are thought to promote bonding and positive social behaviors to sustain connections over time in order to fulfill parental duties.

There is no hard and fast timeline for how long each phase lasts, as it can vary widely due to gender, age, and other environmental factors, Fisher writes.

Additionally, while oxytocin has long gotten the credit for being the love hormone, Prause says that scientists are now "kind of over oxytocin," because it has broader functions than simply bonding. It also plays a role in the contraction of the uterus to stimulate birth, instigating lactation, and sexual arousal; low levels have been linked to autism spectrum disorders. 

Now they're focusing on a charmingly named hormone known as kisspeptin (no, really). Produced in the hypothalamus, kisspeptin plays a role in the onset of puberty, and may increase libido, regulate the gonadal steroids that fuel the sex drive, and help the body maintain pregnancy. But Prause says there is a lot more study about the role kisspeptin plays in attraction.

CHEMICAL AND PERSONAL BONDS

Biology may explain our initial attraction and the "honeymoon" phase of a relationship, but it doesn't necessarily explain why a person's love of obscure movies or joy of hiking tickles your fancy, or what makes you want to settle down.

The Arons' numerous studies on this subject have found connection boils down to something quite simple: "What makes people attracted to the point of falling in love—presuming the person is reasonably appropriate for them—is that they feel the other person likes them," he says. 

In the process of doing research for her book How To Fall in Love With Anyone, writer Mandy Len Catron of Vancouver became her own test subject when she came across the research the Arons are most well-known for: their 36 questions, which promote bonding.

The questions were originally designed to "generate intimacy, a sense of feeling similar, and the sense that the other person likes you," Aron explains. Romantic love wasn't the goal. "It was a way of creating closeness between strangers."

The Arons first tested their questions by pairing up students during a regular class section of a large psychology course, as they related in a paper in the journal Personality and Social Psychology Bulletin. Some students were paired with someone of the same sex, while others were matched with someone of the opposite sex. Each partner then answered a series of 36 increasingly personal questions, which took about 45 minutes each. (Question 2: "Would you like to be famous? In what way?" Question 35: "Of all the people in your family, whose death would you find most disturbing? Why?") Small talk during class hadn't made them bond, but the questions made the students feel closer.

In another version of the study, heterosexual, opposite-sex pairs follow the 36-question session with four minutes of staring deeply into each other's eyes.

Catron decided to test these methods out with a casual acquaintance, Mark, over beers at a local bar one night. They were both dating other people at the time, and no one exclusively. As she answered the questions and listened to Mark's answers, "I felt totally absorbed by the conversation in a way that was unlike any of the other first dates I was having at the time with people I met online," Catron tells Mental Floss.

She was ready to skip the four minutes of soulful eye gazing, but Mark thought they should try it. "It was deeply uncomfortable, but it was also an important part of the experience," she recalls. "It's so intimate, it requires you to let your guard down."

The process instilled in Catron a deep feeling of trust in Mark and a desire to know him better. Within three months, they began dating in earnest. Now, more than three years later, they live together in a condo they bought.

The Arons' questions offer "accelerated intimacy," she says, in a time of increasingly online-driven dating experiences.

A LITTLE MYSTERY, A LOT OF SHARED VALUES

Despite all that we’ve learned, scientists may only ever be able to brush up against the edge of a true understanding of "chemistry." “We understand a fair amount about what happens when [attraction has] already occurred, but we're really bad at predicting when it will happen," Prause says. "People who try to claim magical matchmaking, or that they're going to somehow chemically manipulate an aphrodisiac or something—well good luck! Because we can't figure it out.”

And anyway, what's romance without a little mystery?

If you must have a definitive answer to the puzzle of interpersonal chemistry, Prause says to keep this in mind: "The best predictor of long-term outcomes is shared values."

This piece originally ran in 2018.

10 Citizen Science Projects That Need Your Help

A citizen scientist takes a photo of scarlet mushrooms.
A citizen scientist takes a photo of scarlet mushrooms.
lovelypeace/iStock via Getty Images

Channel your inner Nikola Tesla or Marie Curie by participating in actual scientific research, either out and about or without even leaving your couch. These projects unleash the power of the public to be places that researchers can’t be and to spread the workload when data start piling up. They really can’t do it without you.

1. Catalog photos of Earth's cities at night.

Photo from space of a city at night
Identify cities from the photos taken from the International Space Station.
Chris Hadfield, NASA // Public Domain

Cities at Night—a study by Complutense University of Madrid—asks people to catalog images of the Earth at night taken from the International Space Station, part of the millions of images in the Gateway to Astronaut Photography of Earth database. The current project, Lost at Night, needs people to identify cities within images of 310-mile circles on Earth. Hundreds of volunteers have classified thousands of images already, but classification by multiple individuals ensures greater accuracy. In fact, the project will determine the optimum number of people needed. The primary goal is an open atlas of publicly available nighttime images. Just log on to the image database to help.

2. Follow fish using high-tech tags.

You’ll have to go fishing—an outdoor activity you can do by yourself!—for this assignment. Volunteer to tag fish for the American Littoral Society, whose citizen scientists have tagged more than 640,000 fish since the program began in 1965. You can tag the fish you catch and release, or report tagged fish to the organization. The data is sent to the National Marine Fisheries Service Laboratory in Woods Hole, Massachusetts, where it helps scientists track the populations and movements of coastal species like striped bass, flounder, and bluefish. To get started, become a member of the American Littoral Society, which comes with a packet of tagging gear and instructions.

3. Spy on penguins in Antarctica.

Penguins on an ice floe
Keeping tabs on penguins is one way a citizen scientist can lend a hand.
axily/iStock via Getty Images

Here's another project for those stuck indoors. Penguins are threatened by climate change, fisheries, and direct human disturbance, yet scientists have little data on the birds. To fill in the gaps, 50 cameras throughout the Southern Ocean and Antarctic Peninsula take images of colonies of gentoo, chinstrap, Adélie, and king penguins year-round. You can help the University of Oxford-based research team by sorting through thousands of images to identify and mark individual adult penguins, chicks, and eggs. You'll be pinpointing seasonal and geographic variations in populations that may represent changes to the Antarctic ecosystem. Marking other animals in the images helps researchers figure out which ones are hanging around penguin colonies. Discuss a specific image or the project with the science team and other volunteers in an online forum.

4. Battle an invasive marine species.

Like to dive or snorkel? Make it count by reporting lionfish sightings or captures to the Reef Environmental Education Foundation's Volunteer Reef Survey Project. Lionfish, which are native to the Indo-Pacific, were first sighted in the South Atlantic in 1985 and were likely released by private aquarium owners. Since then, they have spread throughout the Caribbean and Gulf of Mexico and caused native fish populations to decline by up to 80 percent. Scientists say this invasion may be one of the century’s greatest threats to warm temperate and tropical Atlantic reefs. You can also join a lionfish derby to catch and kill some of the tasty fish so scientists can analyze their biology.

5. Count birds from your backyard.

Bluebirds at a bird feeder
Bluebirds dine on mealworms at a bird feeder.
MelodyanneM/iStock via Getty Images

North American birds are in trouble. Recent studies predict dramatic declines in the populations of migratory birds due to climate change—and much of the data that went into these studies came from citizen scientists who monitored species without leaving home. The Cornell Lab of Ornithology and Birds Canada launches Project FeederWatch in the winter months; you simply put out a bird feeder and report the number and species of birds that visit it. Citizen scientists can also join the Cornell Lab's NestWatch—you find a nest, monitor it every three or four days, and report your data. And every February, the Audubon Society runs the Great Backyard Bird Count, in which participants submit data to produce a real-time snapshot of bird populations across North America. Any time of the year, birdwatchers can submit lists of the birds they see on eBird, a huge database of sightings that informs public policy, conservation efforts, and other initiatives.

6. Photograph plants for climate change research.

The Appalachian Mountain Club's Mountain Watch program asks hikers to document alpine and forest plants for ecological research. By taking photos of flowers and fruiting plants along woodland trails and uploading them to the iNaturalist app, participants provide data about the times and places that plants bloom. Scientists then compile the information in an online database and analyze it for trends that could indicate changing climates.

7. Comb through ships' logbooks for weather data.

Old handwritten letters
Practice your handwriting-deciphering skills on the Old Weather project.
scisettialfio/iStock via Getty Images

Ships’ logs from mid-19th century American sailing vessels contain detailed weather observations. Citizen scientists can help transcribe observations from whaling vessels for the Old Weather project; scientists will use the information to learn more about past environmental conditions and create better climate models for future projections. Historians will also use the data to track past ship movements and tell the stories of the people on board.

8. Make American history documents and science notes accessible to more people.

The Smithsonian Libraries are stuffed with original history and science documents that have lain in drawers for decades. Help open up "America's attic" to the public by organizing and transcribing digital versions of handwritten field notebooks, diaries, logbooks, specimen labels, photo albums, and other materials. You'll join thousands of other volunteers to investigate documents like the Sally K. Ride Papers, the collection of the Freedmen's Bureau (which helped former slaves following the Civil War), and field studies of insects by the Irish naturalist Arthur Stelfox.

9. Investigate historical crimes in Australia.

Drawing of a convict ship to Australia
A drawing of a 19th-century convict ship destined for Australia.
Photos.com/iStock via Getty Images

If you're obsessed with true crime, you'll love this project. Volunteer to investigate and transcribe criminal records from 19th- and 20th-century Australia, which was founded as a British penal colony. Alana Piper, a postdoctoral research fellow at the Australian Centre for Public History at the University of Technology Sydney, will use the transcriptions to construct the "life histories and offending patterns of Australian criminals" from the 1850s to the 1940s. More than 40,000 subjects have been completed so far.

10. Map the unique features of Mars's South Pole.

Travel to Mars—without the hassle of zero gravity or space-vegetable farming—through Planet Four, a citizen science project that is currently tasked with identifying features on Mars's dynamic South Pole. Volunteers examine photos from the HiRISE camera on NASA's Mars Reconaissance Orbiter and pick out "fans" or "blotches" in the landscape of seasonal carbon dioxide ice. Scientists believe these structures indicate wind speed and direction on the Martian surface and offers clues about the evolution of the Red Planet's climate.

Why Cats Like to Shove Their Butts in Your Face, According to an Animal Behavior Expert

This cat might be happier showing off its butt.
This cat might be happier showing off its butt.
Okssi68/iStock via Getty Images

Cats are full of eccentric behaviors. They hate getting wet. Their tongues sometimes get stuck midway out of their mouths, known as a “blep.” And they’re really happy hanging out in bodegas.

Some of these traits can be explained while others are more mysterious. Case in point: when they stick their rear end in your face for no apparent reason.

Are cats doing this just to humiliate their hapless caregivers? What would possess a cat to greet a person with its butt? Why subject the person who gives you food and shelter to such degradation?

To find out, Inverse spoke with Mikel Delgado, a postdoctoral fellow at the School of Veterinary Medicine at UC Davis. According to Delgado, cats don’t necessarily perceive their rectal flaunting as anything aggressive or domineering. In fact, it might be a cat’s way of saying hello.

“For cats, it’s normal for them to sniff each other’s butts as a way to say hello or confirm another cat’s identity,” Delgado said. “It’s hard for us to relate to, but for them, smell is much more important to cats and how they recognize each other than vision is. So cats may be ‘inviting’ us to check them out, or just giving us a friendly hello.”

For a cat, presenting or inspecting a butt is a kind of fingerprint scan. It’s a biological measure of security.

Other experts agree with this assessment, explaining that cats use their rear end to express friendliness or affection. Raising their tail so you can take a whiff is a sign of trust. If they keep their tail down, it’s possible they might be feeling a little shy.

If you think this situation is eased by the fact you rarely hear cats fart, we have bad news. They do. Because they don’t often gulp air while eating, they just don’t have enough air in their digestive tract to make an audible noise. Rest assured that, statistically speaking, there will be times a cat giving you a friendly greeting is also stealthily farting in your face.

[h/t Inverse]

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