They say sex is the key to a happy marriage and now science suggests it’s true.
Orgasms rewire the brain in ways that foster long-term bonding, according to new research.
A team of researchers from the University of Texas at Austin and Cold Spring Harbor Laboratory mapped the brains of male and female voles during their three stages of courtship: mating, bonding, and “continuous bond maintenance.”
They found that during these stages, 68 different regions of the brain underwent significant changes, rewiring and forming new connections.
Both members of a couple showed similar brain changes, and the biggest changes seemed to occur when the man had an orgasm.
This could mean that orgasms promote a connection beyond sex, something scientists believe is true for people, too.
Experiences change the brain, creating new connections between neurons and pruning old ones. Scientists use the vole as a model to examine the neuroscience of sex and love because it forms bonds that last a lifetime.
Sex can be more than just a benefit in long-term relationships. New research on voles suggests that sex is an important part of brain remodeling to support a lasting connection.
These changes could reflect evolutionary adaptations that increase the chances of survival, as a bonded pair will have a higher chance of successfully raising their shared babies.
“Brain and behavioral data suggest that both sexes may have similar responses to orgasms, and these ‘orgasms’ coordinate the formation of a bond,” said study author Steven Phelps, a professor of integrative biology at UT Austin, in a statement.
“If true, it would imply that orgasms may serve as a means of promoting connection, as has long been suggested in humans.”
The researcher saw that the most significant predictor of these changes was male orgasm, which appeared to affect brain changes in both men and women.
In other words, the more the man orgasmed, the deeper the brain rewiring of him and his partner. They couldn’t say when or if the females had an orgasm.
Prairie voles form lifelong bonds. A close-knit couple will comfort each other when stressed, defend their shared territory, and raise their children together.
The study used prairie voles, a type of rodent species that has become an unlikely scientific window into how the brain handles sex and love.
These small North American animals form lifelong pairs, so scientists use them to study the neuroscience and behavior of monogamy.
Of course, not all humans are monogamous.
But studies have shown that both prairie voles and humans express oxytocin, which has been called “the love hormone” for its role in bonding, both between romantic partners and between mother and child.
In the new study, scientists started with voles that had never mated, to make sure their brains were blank slates, sexually speaking.
The team used wild-caught voles, a strategy that more and more laboratories are adopting in recent years, which may help avoid some of the reproducibility problems associated with inbred laboratory animals.
After giving the females a hormone injection to ensure they were in heat, the scientists paired them with males.
About 200 voles were paired and the scientists carefully observed their behavior and recorded everything the animals did.including mating, grooming, and even orgasm.
When the animals were about 10 weeks old, they were euthanized and the researchers preserved their brains.
They mapped all the connections in them and then did statistical analyzes to link their behaviors with what they observed in the brains.
Previous research has suggested that sex hormones like estrogen and testosterone, which are not the same between men and women, play important roles in bonding and sex.
But there were no significant differences between the brains of men and women, the researchers reported.
The scientists used light sheet fluorescence microscopy (LSFM) imaging to examine the voles’ brains after they formed pair bonds. They found that many areas were involved, areas that were not previously known to be associated with sex and bonding.
“That was a surprise,” Phelps said.
“Sex hormones such as testosterone, estrogen and progesterone are important for sexual, aggressive and parenting behaviors, so the prevailing hypothesis was that brain activity during mating and bonding would also be different between the sexes.”
What they did find was that many areas that changed during bonding were not previously known to be related to bonding.
In fact, they identified 68 brain regions that had formed new connections during the pair-bonding process.
The study was published in the journal eLife.
Voles are known to form pair bonds quickly, going from strangers to companions in the span of a day.
And sex is a crucial part of this bonding process, the researchers found.
Often within the first 30 minutes of meeting, a male and female vole will begin having sex and continue to do so repeatedly.
During this time, they form a bond that often lasts a lifetime.
A pair of bonded voles will groom each other, raise their young together, comfort each other when stressed, and defend their territory and their shared young.