"Can we truly speak of love as a universal phenomenon, or is it a mental construct shaped by our needs, expectations, and social environment?""What is the reader question of the week?" Toussaint Momenga asks us on our Facebook page. Thank you all for your participation.
From a biological point of view, romantic love (that Neuroscience differentiates between parental love, friendly love, etc.) appears as a remarkably universal mechanism. In humans, as in other animal species, romantic love is a universal mechanism characterized by specific physiological and behavioral signatures, as we explained in a previous article entitled " In love, is everything predetermined?“.
What are these signatures we're talking about? First, the surge of oxytocin, which, at the beginning of a relationship, fosters attachment and positive interactions, while reducing the risk of short-term separation. This hormone, which acts both in the blood and in the brain, doesn't work alone: it interacts with dopamine, a pillar of the reward system, explaining why being in love shares striking traits with addiction… and why heartbreak sometimes resembles a true withdrawal.
Read alsoWhy do we suffer so much after a breakup?
Oxytocin and dopamine aren't the only substances that play a role in romantic attachment. Vasopressin (attachment and fidelity), serotonin (well-being), cortisol (stress), and testosterone (desire) also contribute. Stress hormones like cortisol are primarily present during the first six months of a relationship, caused by insecurity and potentially leading to mood swings. There serotonin, nicknamed "the feel-good hormone", replaces it in the next phase and then, after a year or two of relationship, cortisol and serotonin return to normal: this is the more lasting phase, sometimes called "companion love".
In men, testosterone is the primary hormone responsible for sexual arousal. It tends to decrease in married individuals, and even more so when they spend time with their children. In women, whether sexual desire is primarily dependent on estrogens or androgens (such as testosterone, which women also produce, albeit in smaller quantities) remains a subject of debate.
Romantic love can be seen in the brain
Love is also reflected in the brain. Seeing the face of a loved one activates the ventral tegmental area or the caudate nucleus, key regions for motivation and pleasure. At the same time, certain neural pathways involved in the critical evaluation of others are temporarily deactivated, as demonstrated by Harvard University (USA). Love is therefore not blind, but biased: it colors perception, making it more optimistic as long as the relationship is stable, and more clear-sighted as soon as conflicts or breakups arise.
However, reducing love to a mere hormonal storm would be equally simplistic. Romantic relationships unfold over time, shaped by genetics—variations in oxytocin receptors influence empathy and marital stability—but also by experience, social norms, and emotional investment. Researchers thus emphasize that the probability of separation decreases over time, as partners become more committed. "Across cultures, the probability of separation decreases sharply over time as investment in relationships increases and unsatisfactory marriages are eliminated. This pattern is precisely what one would expect if human pair bonding were 'designed' to produce successful long-term relationships.", explains a study published in the journal Perspectives on Psychological Science in 2015.
The survival of the offspring is at stake
Evolution provides a crucial key here. Romantic love appears to derive from parental love, adopting its hormonal and behavioral markers, while adding sexual desire. This transformation would have favored the survival of exceptionally dependent human offspring, in a context of increasingly large brains and early birth. Long-term monogamy, observed in many large-brained species, thus appears less as a moral norm than as an adaptive strategy.
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