For science, the most likely match is between genetically different

Have you ever been on a date that went nowhere due to lack of chemistry? You had common interests, got along well, and might even have liked each other’s looks, but the date didn’t go any further. Okay, love has those. And his absence too. But the next time that happens and you’re trying to figure out why it didn’t work, remember that the answer may lie in your genetic code.

When the Beatles released the album “Abbey Road” with the song “Because”, which says “Love is old, love is new. Love is all, love is you”. . Love is everything, love is you”), hardly anyone imagined they were being so literal. Yes, one of the possible culprits for falling in love is within us and it is so old that it guaranteed the perpetuation of the species as we know it today.

As an evolutionary question, the genes we carry may be one of the variables in this intricate calculation of attraction. Especially the part of the genome responsible for the body’s defense, the MHC or HLA, which are acronyms in English for the Major Histocompatibility Complex.

Several studies, from Switzerland to the United States, from Germany to Brazil, indicate that this chromosomal region referring to the immune repertoire interferes in the choice —which we believe to be so magical and irrational— of a possible partner. Even if the saying goes that “opposites attract”, the scientific evidence corrects it: it’s genetically different people who attract each other.

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Even if the saying goes that ‘opposites attract’, scientific evidence corrects it: it’s genetically different people who attract each other.

Image: Getty Images

Professor Maria da Graça Bicalho, director of the Laboratory of Immunogenetics and Histocompatibility at the Federal University of Paraná (UFPR), explains that each of us has a unique MHC and that this variability makes us more or less susceptible and resistant to different threats. to our immune system: “Over the evolution of species, we have developed mechanisms to ensure diversity in MHC genes. One of these strategies is associated with reproduction, in particular the choice of a partner with a different MHC”.

Did you like the smell? maybe it works

From this theory, the nose is promoted to the angelic role of Cupid: “Each of us has a tissue HLA identity that also echoes into a unique scent HLA identity. And that influences mate choice,” she says. That is, this genetic mark of our cells is manifested in the smell we exhale and smell, through controversial pheromones, gives us clues about the future of flirting.

In the 1990s, it was already known that female mice preferred males with a different MHC than theirs. But in 1995, Swiss biologist Claus Wedekind set out to test the theory on humans. The famous experiment would have yielded a picture worthy of an open television program on Sundays: Wedekind and his colleagues at the University of Lausanne asked a group of men to wear the same shirt for a few days, without deodorant or perfume. Then they gave the clothes to the women to smell. They best rated men who had the most distinct MHC possible from theirs.

This research served as a model for many others, including one conducted with Brazilian students at UFPR and led by Bicalho. The national version replaced sweaty clothes with necklaces with cotton sachets used for a week and reached conclusions very close to the Swiss. Four years later, Maria da Graça’s team used a database on the population of southern Brazil to analyze genetic information from stable couples and saw that, in most of these romantic couples, there was a big difference in MHC.

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‘And I have to remember that these biological factors are not the only ones’, says expert

Image: Getty Images

Does that mean that in order to find someone to spend Valentine’s Day with, we should go around sniffing necklines? It can be more fun than swapping likes on dating apps — unless you’re pregnant or on the birth control pill. In such cases, Swiss testing has shown that women prefer men with MHC similar to their own.

“It is possible to say that from a biological point of view, the one that we share with other species, we are looking for partners with MHC different from ours. But it is necessary to remember that these biological factors are not the only ones, nor are they prevalent in our species. partner is not restricted to the biological component and there are other preferential values ​​(social, cultural, ethical, economic…) that enter into this equation, confusing or minimizing the preferential choice for the different MHC partner”, says Bicalho to universe.

In the book “The Secret Life of the Mind”, Argentine neuroscientist and reference in the study of decisions Mariano Sigman cites Wedekind’s experiment to explain why we feel what we do: “Many emotional and social decisions are much more stereotyped than we recognize. In general, this mechanism (the MHC) is masked in the mystery of the unconscious and, therefore, we do not perceive the deliberation process. questions”.

But the idea that smell can be a guide to the heart has been criticized. Many scientists dispute the existence of pheromones, as is the case of otolaryngologist and olfactory researcher at the University of Pennsylvania Richard Doty, who argues that our odors are determined by bacteria.

“The idea that there are these magical genes that are somehow associated with scents that permeate the environment and dictate our attraction to people is nonsense. New York would be in a constant state of chaos with people jumping on each other.”

‘Love is thought’

Love is not simple either from a sociocultural or scientific point of view. So its relationship with genetics is to be expected to go beyond MHC. As far as is known, other important players are neurotransmitters, the body’s chemical messengers.

Depending on the expression of oxytocin receptor genes, for example, known as the love hormone, a person can be more or less empathetic, and be prone or not to have long-term relationships.

couple - Getty Images - Getty Images

The idea that smell can be a guide to the heart has been criticized.

Image: Getty Images

Research conducted by the Department of Experimental Psychology at the University of Oxford looked at different neurochemical reception genes, and found that this particular substance plays a key role in romantic love, because it is associated with the way we cling to and empathize with each other.

The genes for dopamine, a protein linked to emotions and pleasure, can interfere with how much we engage with the people around us and with the size of our social circle. They noticed that serotonin, that famous happiness neurotransmitter, indicates how obsessive we can be about love.

Starting from the same logic that genetics affects several personality traits relevant to the way we relate to each other, there are those who have investigated what our genes can say about sexual behavior.

The group led by neuroscientist Bianca Acevedo, from the University of California at Santa Barbara, for example, also examined genetic interference in the reception of certain neurotransmitters. They found that genes linked to oxytocin and the hormone vasopressin could give clues about the romantic commitment of individuals, as well as the frequency and satisfaction of their sex life.

the formula of love

For evolutionary anthropologist Anna Machin, who was part of the Oxford study of neurotransmitters and is the author of the book “Why we love”, love is a chemical reaction in the brain covered by several layers of culture. In an interview with the English university, she answered what is, after all, the essence of this feeling:

Neurochemistry is what underlies love in all cultures, while cultural approaches to love can change and there are cultural differences depending on political systems, place, legacies of romantic poetry of societies, etc. There are even societies that reject cultural concepts of romance, but neurochemistry remains. Homosexuality is an example of how a neurochemical process takes place despite cultural pressure against it in many societies, because biological processes are the roots of our behavior.

Anna Machin, evolutionary anthropologist

Paying well, the match comes

Last year, the sci-fi series “The One” debuted on Netflix based on a reality in which couples are no longer formed by (sometimes) good old-fashioned flirting, but by DNA compatibility tests. Needless to say, the consequences of forming perfect couples in the laboratory take on suspenseful contours. But the fictional chaos doesn’t seem to have discouraged companies that, in real life, sell genetic tests to couples.

This is the case of Canadian companies DNA Romance and Instant Chemistry. With the slogan of “Science-Based Online Dating”, the first is aimed at single people and combines genetic markers with psychological personality tests. The second works on three fronts, neuro, bio and psycho compatibility, to reduce conflicts, keep the flame of the relationship lit and, in their words, “help couples achieve their goals”. Instant Chemistry’s complete kit costs US$259, just over R$1,200.

Before opening your wallet and testing your saliva in search of someone “genetically ideal”, it is worth remembering that scientists themselves recognize that we need more experiments on the subject. After all, DNA may be a path, but it is not a destination. And love, in all its beauty and complexity, is far from a sentence.

About Raju Singh

Raju has an exquisite taste. For him, video games are more than entertainment and he likes to discuss forms and art.

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