Nandkumar M. Kamat
As Valentine’s Day approaches on February 14, 2025, love is in the air—literally and
biochemically.
I wrote an article, ‘Magical Chemistry of Love’, in this column on February 10, 2019. Since then, much research has been done with new techniques and technologies.
The Valentine’s Day culture was introduced in Goa by post-liberalisation market forces in 1992. It has now swept India, the land of Vatsyayana, the creator of Kamasutra, the world’s first real tome on the art and science of love. While poets, writers, and philosophers have long explored love’s mysteries, modern science has progressively unravelled the intricate biochemistry that underpins human attraction, affection, and attachment. Love is not just an emotional or cultural construct; it is a complex neurochemical and physiological process that involves a cocktail of hormones, neurotransmitters, and neural pathways. Love unfolds in stages, from the rush of excitement in new romance to the enduring bonds of long-term commitment, each mediated by specific biochemical processes.
Scientists now understand that love is more than a fleeting feeling—an evolutionary mechanism that facilitates human bonding, reproduction, and survival. Biologists and neuroscientists categorise love into three overlapping yet distinct stages: lust, attraction, and attachment. Each stage engages different hormones and neurotransmitters, influencing how we experience love and relationships. Lust, or sexual desire, is the initial phase of love, primarily driven by the sex hormones testosterone and estrogen. While often associated with reproduction, these hormones shape behaviour, confidence, and attraction. Testosterone, though present in both sexes, is more dominant in men. It fuels sexual desire, increases competitiveness, and enhances physical attraction. Higher testosterone levels correlate with increased risk-taking behaviour, often observed in courtship rituals. Estrogen, predominant in women, plays a role in improving physical attractiveness and growing receptivity to romantic advances, particularly during ovulation when fertility peaks. The hypothalamus, a key brain region, regulates the release of these hormones, influencing sexual drive and mate-seeking behaviour. Lust serves an evolutionary purpose by motivating individuals to seek partners and engage in reproductive behaviour. However, it is only the beginning of the love journey.
When someone falls in love, they experience a surge of neurochemicals that heighten focus, motivation, and pleasure. This stage, often characterised by obsessive thoughts and a sense of euphoria, is mediated by dopamine, norepinephrine, and serotonin. Dopamine, the brain’s reward chemical, is crucial in the pleasure and motivation systems. Released by the ventral tegmental area (VTA) and activating the nucleus accumbens, dopamine creates the high associated with romantic attraction. This is the same brain circuitry involved in drug addiction, explaining why new love can feel intoxicating. Norepinephrine, closely related to adrenaline, causes physiological responses like increased heart rate, heightened attention, and a surge of energy. It is responsible for the racing heart, sweaty palms, and excitement in the presence of a loved one. Serotonin levels drop during the attraction phase, which can result in obsessive thinking about the partner. Studies suggest that serotonin levels in individuals newly in love resemble those in people with obsessive-compulsive disorder, explaining the all-consuming nature of early romance.
Neuroscientific research using functional magnetic resonance imaging (fMRI) has revealed that the brain areas activated by love are like those stimulated by addictive substances. The same regions that light up when someone is high on cocaine are activated when they think about their romantic partner. This explains why early-stage love can be so consuming and exhilarating.
For love to last beyond the initial high, a shift from dopamine-driven attraction to a more stable and secure bond occurs. This phase is mediated by oxytocin and vasopressin, which promote trust, intimacy, and long-term attachment. Oxytocin, known as the “cuddle hormone” or “love hormone,” is released during physical touch, hugging, and sexual activity. It strengthens emotional bonds, promotes trust, and facilitates long-term pair bonding. Vasopressin is associated with monogamous behaviour and protective instincts toward a partner. Studies on prairie voles—one of the few monogamous species in the animal kingdom—show that vasopressin levels determine their likelihood of forming lifelong bonds. Long-term relationships benefit from these bonding hormones, which provide emotional stability and a sense of security. Couples with higher oxytocin levels tend to report greater relationship satisfaction
and trust.
Love is not just a source of emotional fulfillment—it profoundly affects health and well-being. Numerous studies have demonstrated that strong romantic and social bonds correlate with improved mental and physical health. Love reduces cortisol, the stress hormone. While early-stage love is associated with a spike in cortisol due to nervous excitement, long-term love lowers cortisol levels, leading to better stress management. Loving relationships are linked to lower blood pressure, reduced risk of heart disease, and better overall cardiovascular health. Oxytocin and dopamine contribute to immune system regulation, improving resilience against infections and diseases. Love activates brain pathways that help alleviate pain. Studies have shown that looking at a loved one’s photograph can significantly reduce pain perception. Conversely, heartbreak and emotional loss activate the same brain circuits associated with physical pain. Studies indicate that the anterior cingulate cortex, a brain region linked to pain processing, becomes highly active during romantic rejection, explaining why breakups can feel physically painful.
While love is a universal human experience, some individuals struggle to form or maintain romantic relationships. These challenges can be attributed to variations in hormone levels, neurotransmitter imbalances, genetic factors, and life experiences. Studies suggest that variations in oxytocin receptor genes (OXTR) may influence attachment styles and the ability to form strong romantic bonds. Individuals with different dopamine receptor profiles (such as those with the DRD4 gene variation) may be more prone to novelty-seeking behaviour, making them less inclined toward monogamy.
Childhood experiences with caregivers shape adult attachment styles. Securely attached individuals tend to have healthier relationships, while those with avoidant or anxious attachment styles may struggle with intimacy. Understanding these biological and psychological factors can help individuals navigate relationship challenges and develop healthier romantic connections.
In 2025, the way people experience love is evolving. Advances in artificial intelligence, virtual reality, and biotechnology are reshaping relationships in unprecedented ways. Dating platforms now integrate biometric compatibility testing, analysing heart rate variability, voice tone, and even pheromone responses to match users based on biological and psychological compatibility. Some scientists are exploring the possibility of love drugs—pharmaceuticals that enhance oxytocin or dopamine levels to strengthen romantic bonds or rekindle lost passion in relationships. Long-distance relationships benefit from immersive experiences that allow partners to feel connected despite physical separation. While these innovations raise ethical questions, they highlight how the intersection of technology and love will continue to shape human relationships in the years to come.
Love is an extraordinary interplay of biology, psychology, and social connection. While we now understand its biochemistry in greater detail, its emotional depth remains as profound. From the primal drive of lust to the euphoric high of attraction and the steady warmth of attachment, love is a complex yet essential part of the human experience.
As we celebrate Valentine’s Day in 2025, we can appreciate love as an age-old romantic ideal and as a scientifically fascinating phenomenon that shapes our health, happiness, and survival. Whether driven by neurotransmitters, hormones, or evolutionary instincts, love remains one of human life’s most exciting and enduring mysteries. Make Valentine’s Day, February 14, a true celebration of love. The post-COVID-19 traumatised society needs a lot of such celebrations.
