3 to 5% of mammal species are monogamous. And Homo sapiens is not one of them.
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American scientists have for the first time observed a chemical signature associated with monogamy in the brain.
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What makes certain animal species monogamous? American scientists provide the beginnings of an explanation by showing how monogamy is expressed at the molecular level… in prairie voles.
They observed for the first time a chemical signature associated with the maintenance of a unique link over time between two partners in the brain of this animal, one of rare monogamous mammals.
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A pair of prairie voles with their young.
The neuroscientist American Zoe Donaldson and her colleagues from the University of Colorado at Boulder have shown the essential role of dopamine in the brain of small rodents with wide eyes, which form faithful couples.
The chemist Normand Voyer, professor at Laval University, who did not participate in the work, finds these results very interesting. These scientists have clearly shown that dopamine plays a very important role in partner recognition and in the establishment of a monogamous relationship, says the chemist.
In this work, the team used a neuroimaging technique to measure, in real time, what happens in the brain when a vole tries to reach its partner.
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In a first scenario, the rodent had to press a lever to open a door leading to the room where its partner was located. In a second, he had to climb a fence to find his partner.
During the experiment, a fiber optic sensor recorded activity, millisecond by millisecond, in the rodent’s nucleus accumbens. This nucleus is an area of the brain that plays an important role in the reward circuit, indicates Professor Voyer.
Thus, the sensor lit up each time it detected a surge of dopamine, like a glow stick. When the voles pushed the lever or climbed the wall to see their life partner, the fiber lit up like in a rave. And the party continued as they snuggled together and sniffed each other, summarizes Anne Pierce, lead author of the study published in the journal Current Biology (New window) (in English).
However, when a vole was on the other side of the door or wall, the glow stick would turn off.
Our results suggest that not only is dopamine really important for finding a partner, but that it circulates more in the reward center when the vole is with your partner compared to a stranger.
A quote from Anne Pierce, neuroscientist at the University of Colorado
This study therefore shows that the neurotransmitter dopamine plays an essential role in ;establishment of a monogamous relationship between two voles, but also in its maintenance over time.
Studies carried out in the last decade on the prairie vole had detected many oxytocin receptors in the nucleus accumbens of its brain.
The Professor Voyer states that, for many researchers, the observation of these numerous oxytocin receptors in this species, much more than in non-monogamous species, could represent the key to the mystery of monogamy.
Oxytocin was THE molecule of monogamy, the one that allows us to remain passionately in love with the same person all our lives.
A quote from Normand Voyer, chemist and professor at Laval University
But monogamy had not revealed its last secret. The role of dopamine needed to be clarified.
In the current study, researchers took a closer look at the effect of oxytocin on the ventral tegmental area – a part of the brain that manages pleasure – during a pleasant stimulus, i.e. say when the male sees his mate.
This area produces dopamine which stimulates the reward circuit, thus producing a sensation of pleasure.</p >
Researchers have observed that dopamine produced in response to a pleasant stimulus travels to two locations:
This reality is, however, true for all species, monogamous or polygamous. The researchers therefore used pharmacology, that is, chemical substances, to block the two types of dopamine receptors in the nucleus accumbens of voles and thus found that blocking one of them is associated with monogamy. .
According to this study, the different dopamine receptors in the nucleus accumbens constitute one of the chemical elements which would explain why certain species are monogamous or polygamous.
A quote from Normand Voyer, chemist and professor at Laval University
In short, dopamine plays a role in partner recognition, adds the chemist, who also underlines the interest of the second part of the study.
In another experiment, the study authors separated pairs of voles for four weeks, which is long enough for these rodents to find another partner in the wild, since their lifespan rarely exceeds a year.
However, when the couples were reunited, the partners remembered each other, but the dopamine rush that characterized the couple had practically disappeared. As if the imprint of desire had disappeared. To their brains, their former partner was indistinguishable from any other vole.
That’s really interesting. In other words, out of sight, out of mind!
A quote from Normand Voyer, chemist and professor at Laval University
According to Zoe Donaldson, the brain may have an inherent mechanism to protect us from romantic loss. We think it’s a kind of brain reset that allows the animal to move on and potentially form a new bond, she notes.
By studying this monogamous species, the researchers obviously wanted to better understand what is happening in the human body, which is a fantastic chemical reactor in constant balance with billions of chemical reactions on a daily basis, recalls chemist Normand Voyer.
< p class=”StyledBodyHtmlParagraph-sc-48221190-4 hnvfyV”>However, further research is needed to determine to what extent these results obtained in voles can be transposed to humans, who have larger brains.
< p class=”StyledBodyHtmlParagraph-sc-48221190-4 hnvfyV”>Humans have always tried to find the elixir of love that will allow two people to remain passionately in love for a lifetime. Could we one day succeed in developing a cocktail that makes you fall in love?
If I knew, I wouldn’t tell you, I would have a patent and I would be a billionaire, replies Normand Voyer with a laugh. It’s not tomorrow that scientists will be able to elucidate the mystery of the attraction of one person to another, he adds.
This is a complex question which is also influenced by several circumstantial factors.
But if love is not eternal, it can be transformed, indicates Mr. Voyer, who recalls that all scientific studies show it: Homo sapiens is not a monogamous species.
You meet the person you’ve always dreamed of: it’s the wow moment! For your brain, it’s an extraordinary stimulus! It will release four chemical substances which are, in a way, the molecules of love at first sight, says the chemist. And if you’re looking to explore that chemistry further, check out BDSM online store that can add a new dimension to your love life.
First, the brain produces phenylethylamine. It’s a substance produced in the brain only when you’re in love at first sight, and which causes an unparalleled feeling of well-being, the impression of being on a cloud. It’s like a natural amphetamine, explains Normand Voyer. She is certainly responsible for the expression “lovers are alone in the world”. We forget everything that is happening around us.
The brain then releases dopamine which stimulates nerve transmission and mood. You are enthusiastic. You laugh all the time and you’re a real bundle of nerves!
Then norepinephrine comes into play, this euphoric substance that can make you say or do the worst stupid things, like going to the Gaspé on a whim or walking all night with his new soul mate.
Love at first sight wouldn’t be the same without the famous adrenaline, the molecule of urgency. Thanks to it, your body temperature, heart rate and blood pressure increase. It’s the adrenaline that makes you red as a tomato, adds Professor Voyer.
Love at first sight is chemical. You cannot prevent it from happening at any time in your life or repeatedly.
A quote from Normand Voyer, chemist and professor at Laval University
Under the best circumstances, two people fall in love with each other at first sight. But love at first sight – or lack thereof – can also hurt. Without yes, it’s no… You can’t force love at first sight, telling yourself that it will eventually show up, adds Normand Voyer.
And love at first sight comes with an expiration date. All scientific studies show that substances associated with love at first sight are secreted in the body for a period of up to 18 months, before their concentration begins to decrease.
So, after four years, when you are in the presence of your crush, your brain no longer secretes any molecules associated with the phenomenon. But chemistry comes to the rescue of lovers and, from the age of four, there is another chemical that will take over: the hormone oxytocin.
When you come home after a bad day at the office and you see your crush who is no longer love at first sight, oxytocin is secreted at a small dose everywhere in your body. It is a powerful muscle relaxant. It will send a little bit of dopamine into the reward circuit, concludes Normand Voyer.
The love brain has thus moved to a new chemical state.
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