This article is taken from the monthly Sciences et Avenir – La Recherche n°905-906, dated July-August 2022.
The heart misses a beat, the bowels rotate, the breathing sounds tocsin. If love is felt throughout the body, it is because its orchestra is playing in the brain. There, the three phases of romantic love that form desire, love and then, after two or three years, attachment, involve almost identical chemical compounds. Called neurotransmitters, they are produced by neurons where they serve as messengers, such as adrenaline (stress), noradrenaline (alertness) or dopamine (motivation and reward). In the heart of the brain, in a small area called the hypothalamus, oxytocin and vasopressin, hormones and attachment neurotransmitters, are also produced.
The insula, a small area involved in emotions
During sexual desire, the importance of which decreases during the three phases of love, dopamine overcomes the tension of new intimacy, while noradrenaline increases the reception of signals sent by the desired person. It is also dopamine and associated brain structures – such as the nucleus accumbens that are activated by taking cocaine – that characterize the stage of passion. We will then be especially motivated to be close to the loved one.
This article is taken from the monthly Sciences et Avenir – La Recherche n°905-906, dated July-August 2022.
The heart misses a beat, the bowels rotate, the breathing sounds tocsin. If love is felt throughout the body, it is because its orchestra is playing in the brain. There, the three phases of romantic love that form desire, love and then, after two or three years, attachment, involve almost identical chemical compounds. Called neurotransmitters, they are produced by neurons where they serve as messengers, such as adrenaline (stress), noradrenaline (alertness) or dopamine (motivation and reward). In the heart of the brain, in a small area called the hypothalamus, oxytocin and vasopressin, hormones and attachment neurotransmitters, are also produced.
The insula, a small area involved in emotions
During sexual desire, the importance of which decreases during the three phases of love, dopamine overcomes the tension of new intimacy, while noradrenaline increases the reception of signals sent by the desired person. It is also dopamine and associated brain structures – such as the nucleus accumbens that are activated by taking cocaine – that characterize the stage of passion. We will then be especially motivated to be close to the loved one.
Finally, the attachment grows during the period of passionate love and culminates after a few years, in the phase of the same name. Oxytocin plays an important role in this, but be careful: it is often described as the hormone of love and kindness, it can also, depending on the context, lead to jealousy, possessiveness, even aggression, points out the professor emeritus of neuroscience Marie-José Freund-Mercer, author of “Oxytocin: between myth and reality”. Oxytocin does not work alone: injected into the brain of the prairie vole (monogamous), it induces attachment to the partner, but administered to the mountain vole (polygamous), it has no effect. “Monogamy cannot be reduced by oxytocin alone. Other factors including vasopressin and dopamine play a role, not to mention the presence of their receptors in certain parts of the brain “, supports the scientist. All these chemical actors intervene in particular areas of the brain.
“These are the same neurotransmitters that play in all three phases of romantic love, but the regions of the brain involved are quite different. You can desire without love, and love someone without sexual desire. “, sums up the doctor and biologist Bernard Sablonnière, author of “The Chemistry of Feelings. In one of its folds, the brain houses, for example, the insula, a small area associated with emotions. Neuroimaging has shown that a small area is “activated” there during attachment and another, quite different, during sexual desire. Another example: the amygdala, a zone mainly associated with negative emotions, is “deactivated” facing the face of the loved one, as well as the zone of the frontal cortex that manages social judgment. Why these places? Probably because they are also associated with motherly love, the original form of love.
Biologically, because it involves similar parts of the brain and neurotransmitters, romantic attachment is very similar to mother’s love, confirms Marie-José Freund-Mercier. “The adult attachment system may have evolved from in the attachment system for young children, he suggested. Unlike sexual attraction, which does not exist in the mother-child relationship. “Following this logic, the main theories that explain the emergence of romantic love in the human species are based on the mother’s need to get help from the father to increase the child’s chances of survival. “Three hypotheses stand “, listed Adam Bode, anthropologist who specializes in love at the School of Archeology and Anthropology at the University of Canberra (Australia). child.
Social pressure is added to biological pressure
It could also be love that drives the father to take care of the children with him, but Adam Bode doesn’t believe that. “Father presence is often not associated with better child survival in societies with limited access to health care. “Furthermore, in primates, paternal care evolved later than monogamy. Third hypothesis, pregnant mothers may be attached to males who are able to feed them enough to conceive and a healthy child. “It is likely that many evolutionary pressures have contributed to the evolution of romantic love over the last 5 to 6 million years, around the point where gender. Homo separated from other monkeys “, concluded the anthropologist. This emergence of romantic love is however more of an exception than a rule, because the way of life in pairs is present in only 5% of mammals.
People take the concept of living together to the point of adding social pressure to biological pressure. Throughout human history, the couple has long been synonymous with marriage more than love, until the 1970s, when most people began their lives as a couple by getting married. Thus, “The meaning of marriage has evolved from a union arranged by interests to a ‘marriage of love’ that unites two people who choose each other, explained sociologist Emmanuelle Santelli, director of research at CNRS and specialist in gender and couples. There is undeniably a commandment to live together and a social norm that couples should love each other. “
But why do we dream of a lasting relationship? “Even now, the couple is always together with the idea of a family that plans itself in the long term, from children to grandchildren. “, analyzed the sociologist. This is why romantic love refers to the concepts of love that are long-lasting, exclusive and complementary. This type of union requires choosing your partner carefully. If biology does not yet know -an explain why we choose one person and not the other, it is clear that couples bring together people who are similar to each other socially, line Emmanuelle Santelli: we are talking about social homogamy.
“Couples unite people who are socially equal”
But to be truly interested in romantic love, the context still has to lend itself to it. “In Western literature, romantic fictions are more frequent in times of economic development “, observes the specialist in computational sciences Nicolas Baumard, research director of the CNRS. In a publication by Human Nature Naturehe showed with his team that the higher the standard of living, the greater the proportion of romances that harm other genres. “Improving the standard of living increases the psychological importance of love “, concludes Nicolas Baumard. A fact that has been proven for almost 4000 years, the age of the oldest known fictions, and in all cultures, from China to the Arab world, from of India to the West.
For the researcher, the explanation lies in a stronger affective investment in his family and therefore in his couple if the material conditions allow it. But the question is far from clear. Finally, why do we love? More than a social and biological command, romantic love can only exist because we are capable of it.