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Hormones and Sexual Behavior: Influence on Attraction and Partner Choice

Hormones and Sexual Behavior: Influence on Attraction and Partner Choice
Photo by Womanizer Toys / Unsplash

Hormones act as powerful messengers that drive sexual motivation, shape who we’re attracted to, and influence how we bond with partners. In both men and women, a cocktail of hormones and neurochemicals – including testosterone, estrogen, oxytocin, vasopressin, dopamine, and others – orchestrates the phases of lust, attraction, and attachment (The Science of Love | Infographics). Below, we summarize how these key hormones impact sexual behavior and partner choices, highlighting effects on sexual desire, attraction, pair bonding, and fidelity in both sexes.

Testosterone: Fueling Sexual Desire and Mating Efforts

Testosterone is often called the “sex drive” hormone. Men produce far more testosterone than women (on the order of 10–20 times higher), which largely explains why men typically report stronger baseline sexual desire than women (Testosterone and sexual desire in healthy women and men - PubMed). In both sexes, testosterone boosts libido and sexual thoughts. For example, research finds that within women, higher testosterone levels correlate with greater interest in solo sexual activities (like masturbation) (Testosterone and sexual desire in healthy women and men - PubMed). In men, a minimum threshold of testosterone is crucial for normal sexual desire and arousal; low testosterone can dampen libido, while high levels tend to enhance sexual motivation.

Beyond general libido, testosterone also influences mating behavior and partner preferences. Men with higher circulating testosterone show greater interest in seeking new or multiple sexual partners – a trait linked to evolutionary “mating effort.” Studies have found that men who admit to infidelity have significantly higher testosterone on average than men who remain monogamous (Higher testosterone levels linked to a higher probability of infidelity in men, study finds). In other words, elevated testosterone is associated with a higher probability of cheating in men (Higher testosterone levels linked to a higher probability of infidelity in men, study finds) (Higher testosterone levels linked to a higher probability of infidelity in men, study finds). Conversely, entering a committed relationship or becoming a father can reduce a man’s testosterone. Long-term studies observed that when single men settle into monogamous pair-bonds and especially when they have a newborn, their testosterone levels drop markedly (20–30% or more) (Testosterone Levels Are Negatively Associated with Childlessness in Males, but Positively Related to Offspring Count in Fathers | PLOS ONE) (Testosterone Levels Are Negatively Associated with Childlessness in Males, but Positively Related to Offspring Count in Fathers | PLOS ONE). This decline is thought to shift a man’s focus from seeking new mates to caring for his partner and offspring. Indeed, across cultures, pair-bonded men and hands-on fathers tend to have lower T than single men, while single men or those actively pursuing mates have higher T (Testosterone Levels Are Negatively Associated with Childlessness in Males, but Positively Related to Offspring Count in Fathers | PLOS ONE). This hormonal tuning may promote fidelity and paternal investment by biologically curbing the drive to roam.

In women, testosterone plays a smaller but still important role in sexual motivation. Women’s ovaries and adrenals produce a little testosterone, and even these lower levels can influence libido. Research indicates that boosting testosterone (for instance, in postmenopausal women with low desire) can modestly increase sexual thoughts and arousal (Testosterone therapy in women: Does it boost sex drive? - Mayo Clinic ). Clinically, low-dose testosterone therapy has been used to treat hypoactive sexual desire in women, though safety and efficacy are still being studied (Testosterone therapy in women: Does it boost sex drive? - Mayo Clinic ). Overall, testosterone is a key driver of lustful motivation in both sexes – powering sexual fantasies, attuning the brain to sexual cues, and energizing the pursuit of partners.

Estrogen: Orchestrating Female Sexual Arousal and Attraction

Estrogen (specifically estradiol) is the primary female sex hormone, and it has profound effects on women’s sexual behavior and mate preferences. Estrogen levels fluctuate across the menstrual cycle, peaking in the days leading up to ovulation. These hormonal fluctuations create measurable changes in sexual motivation and attraction. Many women experience a surge in libido around mid-cycle when estrogen (and luteinizing hormone) hit their peak – this is when the body is most fertile, and biology increases the urge to mate. Studies have even shown that women subtly change their behavior and appearance during ovulation: they tend to dress more provocatively and are perceived as more attractive by men when it’s prime time for conception (The Stripper's Secret | Psychology Today). One famous study found that professional lap dancers earned significantly higher tips during their ovulatory phase compared to when they were menstruating or on birth control, suggesting that men can subconsciously detect and respond to women’s fertility cues (The Stripper's Secret | Psychology Today).

Estrogen doesn’t just affect quantity of sexual desire – it may also influence the type of partner women find appealing. Research in evolutionary psychology suggests that during high-fertility days (when estrogen is high), women’s mate preferences shift towards more “masculine” and genetically fit traits. In a meta-analysis of 50 studies, women near ovulation showed a greater attraction to men with masculine faces, bodies, dominant behavior, and even masculine scents (Women more attracted to masculine mates during ovulation) (Women more attracted to masculine mates during ovulation). For example, women were found to prefer the scent of men with more symmetrical, testosterone-linked features during ovulation, presumably because those traits signal good genes (Women more attracted to masculine mates during ovulation). This fertile-phase preference is thought to be an evolutionary adaptation – essentially, estrogen is nudging women to seek high-genetic-quality mates when they can conceive (Women more attracted to masculine mates during ovulation). After ovulation, as estrogen falls and progesterone rises (luteal phase), women’s priorities may shift toward comfort, security, and nurturing. They tend to feel more attracted to traits suited for long-term partnership (e.g. kindness, reliability) and often experience a drop in sexual interest toward outside men.

Hormonal studies support these behavioral patterns. Higher estradiol levels have been linked to extra-pair attraction – women with naturally higher estrogen on a given day report relatively greater interest in men other than their primary partner (Hormonal predictors of women's extra-pair vs. in-pair sexual attraction in natural cycles: Implications for extended sexuality - PubMed). In contrast, high progesterone (which dominates the latter half of the cycle) is associated with increased feelings of attachment to one’s own partner and lower interest in flirting with new men (Hormonal predictors of women's extra-pair vs. in-pair sexual attraction in natural cycles: Implications for extended sexuality - PubMed). In essence, when estrogen is high, women’s brains may tilt toward seeking quality genes (even, in some cases, through affairs), and when progesterone is high (signaling either post-ovulation or pregnancy), the focus shifts to bonding with a stable partner – a built-in fidelity booster. This dynamic can be seen as nature’s way of balancing mating and bonding: estradiol encourages conception with the best genes, while progesterone promotes commitment to raise any resulting offspring.

Beyond attraction, estrogen is also critical for the physiological aspects of female sexual arousal. It maintains vaginal tissue health, keeps vaginal lubrication high, and boosts blood flow – all important for comfortable, pleasurable intercourse. When estrogen drops (as in menopause), women often experience lower libido, vaginal dryness, and reduced arousal. Many menopausal women find that estrogen therapy or estradiol-based medications can improve vaginal comfort and sometimes sexual interest, underscoring estrogen’s role in female sexual function.

(In men, estradiol is present at much lower levels, but it still has roles – for example, some estradiol (made from testosterone via aromatase) is needed for erectile function and libido. However, testosterone is the dominant hormone driving male sexual behavior, whereas estrogen’s effects are most pronounced in women.)

Oxytocin: The “Love Hormone” and Pair-Bonding Glue

Oxytocin is a peptide hormone and neurotransmitter famed for its role in social bonding. Often nicknamed the “cuddle hormone” or “love hormone,” oxytocin is released during intimate moments – especially during orgasm, affectionate touch, hugging, and breastfeeding. This hormone has a powerful impact on bonding, trust, and long-term attachment in both sexes.

In the brain, oxytocin acts on emotion and reward centers to foster connection. It is produced by the hypothalamus and released both into the bloodstream (where it triggers uterine contractions and milk let-down) and directly into the brain where it affects neurons. Oxytocin has been shown to increase feelings of trust and emotional closeness between people (Hormone affects distance men keep from unknown women they find attractive: Oxytocin may promote fidelity | ScienceDaily). For example, experiments found that people given a dose of intranasal oxytocin became more trusting in economic games and better at reading others’ emotions. In romantic contexts, oxytocin release (such as after sexual orgasm or even during warm physical contact) helps deepen the attachment between partners. Couples with higher oxytocin levels during interaction tend to report greater relationship satisfaction and bonding. This is similar to oxytocin’s essential role in mother-infant bonding – it’s the same chemical that makes a mother feel in love with her newborn during skin-to-skin contact.

One striking finding is that oxytocin may actively promote fidelity in monogamous relationships. A study in the Journal of Neuroscience showed that men in committed relationships, when given oxytocin, kept a larger physical distance between themselves and an attractive stranger woman compared to men given a placebo (Hormone affects distance men keep from unknown women they find attractive: Oxytocin may promote fidelity | ScienceDaily). Notably, oxytocin had no effect on single men – it specifically made attached men less inclined to approach another woman. The oxytocin essentially tipped their brains toward staying loyal to their partner. The researchers dubbed this a “fidelity hormone” effect, echoing earlier animal research in monogamous prairie voles where oxytocin was a key to pair-bond fidelity (Hormone affects distance men keep from unknown women they find attractive: Oxytocin may promote fidelity | ScienceDaily). Thus, oxytocin release during interactions with one’s partner might help reinforce the value of that partner and reduce temptation to stray.

At a neurobiological level, oxytocin’s bonding effects are tied to the brain’s reward circuitry. Oxytocin receptors are found in areas like the nucleus accumbens and ventral tegmental area – regions rich in dopamine that signal pleasure and reward. In monogamous animals like prairie voles, when they mate and bond, oxytocin is released and works together with dopamine to “wire” the partner’s identity to feelings of pleasure (Oxytocin enhances brain reward system responses in men viewing the face of their female partner | PNAS). In humans, brain imaging studies have captured a similar mechanism. In one experiment, men in long-term relationships were given oxytocin or placebo and then shown pictures of their partner vs. other women. Under oxytocin, the brain’s reward centers lit up selectively for their partner’s face, and the men rated their partners as more attractive than other women (Oxytocin enhances brain reward system responses in men viewing the face of their female partner | PNAS). Oxytocin essentially boosted the subjective reward value of their own partner (Oxytocin enhances brain reward system responses in men viewing the face of their female partner | PNAS) (Oxytocin enhances brain reward system responses in men viewing the face of their female partner | PNAS). This neural effect helps maintain the pair-bond by making your partner especially rewarding to you relative to others.

It’s important to note that both men and women produce oxytocin, but some studies suggest women’s bonding may rely on oxytocin a bit more (since females have naturally higher baseline oxytocin, and during childbirth women get a massive oxytocin surge that cements maternal bonds). In contrast, as we’ll see below, men’s pair-bonding may involve a related hormone, vasopressin, in addition to oxytocin (The Neuroscience of Love: What’s Going on in the Lovestruck Brain? - Georgetown University). Overall, oxytocin is a critical hormone for pair-bond formation, affectionate attachment, and maintaining trust between partners. By flooding us with feelings of contentment and connection during intimate moments, it acts as a glue that can hold couples together for the long term.

Vasopressin: Supporting Monogamy, Protection, and Loyalty

Vasopressin (arginine vasopressin, or AVP) is another hormone that plays a major role in social and sexual behavior, particularly in males. Chemically, vasopressin is very similar to oxytocin (both are 9-amino-acid neuropeptides), and like oxytocin, vasopressin is released in the brain during sex and bonding. However, vasopressin’s effects are somewhat different – it has been linked to mate guarding, territoriality, and loyal partner behavior, especially in males (The Neuroscience of Love: What’s Going on in the Lovestruck Brain? - Georgetown University).

Much of what we know about vasopressin’s role in monogamy comes from animal studies with voles. Prairie voles (a species that forms lifelong monogamous bonds) have provided a classic model: Male prairie voles have a high concentration of vasopressin receptors in certain brain areas, and blocking vasopressin in these males prevents them from forming pair-bonds with a mate (Social Bonding – Foundations of Neuroscience). By contrast, their close cousins the montane voles (which are promiscuous and do not pair bond) have far fewer vasopressin receptors and do not form such attachments. In lab tests, male prairie voles will strongly prefer to spend time with their mated partner over a strange female, whereas montane voles show no particular preference (since they never formed a bond) (Social Bonding – Foundations of Neuroscience) (Social Bonding – Foundations of Neuroscience).

(Social Bonding – Foundations of Neuroscience) Prairie voles (a monogamous species) form strong pair bonds after mating, whereas montane voles (promiscuous) do not. In a partner preference test, a male prairie vole spends most of his time with his bonded partner (brown bar) rather than a stranger, but a male montane vole shows no special preference (Social Bonding – Foundations of Neuroscience). This difference is driven by oxytocin and vasopressin acting in the brain’s reward system during mating – prairie voles release these “bonding hormones” and have the receptors to use them, which locks in a monogamous attachment (Social Bonding – Foundations of Neuroscience).

In male prairie voles, vasopressin released after mating triggers bonding behaviors – it makes the male vole devoted to his partner and aggressive toward intruder males. Essentially, vasopressin promotes protective loyalty: the impulse to guard one’s mate and nest. We see hints of analogous effects in humans. While we obviously don’t run controlled mating tests in humans, researchers study genetic differences in the vasopressin receptor and how they relate to men’s relationship behavior. Notably, a variation in the vasopressin receptor gene (AVPR1A) has been associated with less bonding in human males: Men carrying a particular allele (the “334” repeat variant) were more likely to report marital crises or dissatisfaction, and their spouses reported less feeling of closeness to them (Genetic variation in the vasopressin receptor 1a gene (AVPR1A) associates with pair-bonding behavior in humans - PMC ). In contrast, men without this variant (presumably more responsive to vasopressin’s bonding effects) were more stably bonded (Genetic variation in the vasopressin receptor 1a gene (AVPR1A) associates with pair-bonding behavior in humans - PMC ). This finding – often dubbed the “monogamy gene” in media – suggests vasopressin signaling influences how strongly men attach to partners. While human behavior is complex and not determined by a single gene, the link points to an evolutionary continuity: the same vasopressin system that drives vole monogamy plays a role in human pair bonding.

Functionally, vasopressin’s effects complement those of oxytocin. Oxytocin tends to foster nurturing and emotional connection, more so in females (e.g. motherly care, empathy, cuddling), whereas vasopressin promotes defense and commitment behaviors, more so in males (e.g. protecting the family, staying close to a spouse, possibly feelings of sexual jealousy that keep one attentive to the partner) (The Neuroscience of Love: What’s Going on in the Lovestruck Brain? - Georgetown University). Both hormones are released during sex in both men and women, and together they reinforce the emotional bond and sense of attachment after sexual intimacy (The Neuroscience of Love: What’s Going on in the Lovestruck Brain? - Georgetown University). For instance, after intercourse, the rise in oxytocin and vasopressin contributes to the feeling of loving closeness and contentment with one’s partner, which can increase loyalty. In men, vasopressin may be a major reason that sexual intimacy sometimes heightens feelings of possessiveness or exclusivity – it’s essentially telling the male brain “this is your partner.” In women, vasopressin also exists and may play roles in bonding, but oxytocin is usually highlighted as the stronger driver of female attachment, whereas vasopressin is highlighted in male attachment.

In sum, vasopressin is another key “pair-bonding hormone” that, along with oxytocin, helps secure long-term relationships. It tilts behavior toward monogamy by rewarding loyalty and making alternative partners less appealing. Our neurobiology seems to have evolved a dual system: oxytocin for love and trust, vasopressin for loyalty and guarding – together ensuring that once we pair up, we have chemical incentives to stay together and raise our offspring cooperatively.

Other Neurohormones and Mechanisms in Sexual Behavior

While testosterone, estrogen, oxytocin, and vasopressin are major hormonal players, they work in concert with many other neurochemicals to shape sexuality and relationships. Some important ones include:

Dopamine: This neurotransmitter is the brain’s primary pleasure and reward signal. Dopamine surges during sexual arousal and especially during orgasm, reinforcing sexual behaviors by making them intensely rewarding. In the attraction phase of romance (new love or infatuation), dopamine is behind the giddy, obsessive “high” we feel – it’s the same circuit activated by addictive drugs (The Neuroscience of Love: What’s Going on in the Lovestruck Brain? - Georgetown University). Brain scans of people in love show strong activation of dopamine-rich areas (like the ventral tegmental area and striatum) when they see their beloved, similar to the rush of a reward (Social Bonding – Foundations of Neuroscience). Dopamine works closely with hormones: for example, oxytocin and vasopressin interact with dopamine pathways to encode partner bonds (making the partner a source of unique reward) (Oxytocin enhances brain reward system responses in men viewing the face of their female partner | PNAS). Without dopamine, the physical act of sex or the presence of a partner would not produce that “spark” of desire or pleasure. Thus, dopamine underlies sexual arousal, motivation to pursue a mate, and the euphoria of falling in love.

Serotonin: Serotonin is another neurotransmitter that has almost opposite effects to dopamine during attraction. Early-stage romantic love is associated with lowered serotonin (levels akin to clinical OCD), which may explain why new lovers have relentless, intrusive thoughts about each other. In terms of sexual function, a spike in serotonin occurs after orgasm – contributing to the feeling of relaxation and contentment. High serotonin is correlated with satiety (in contrast to dopamine’s craving), so after climax, as serotonin and another hormone prolactin rise, sexual desire temporarily subsides (the refractory period). Medications that increase serotonin (like SSRIs) often have side effects of lowered libido and difficulty achieving orgasm, highlighting serotonin’s role in “putting the brakes” on sexual arousal once the reward is obtained.

Norepinephrine (Noradrenaline): This hormone/neurotransmitter is responsible for the adrenaline rush of sexual excitement. During arousal and intense attraction, norepinephrine levels increase, leading to racing heart, sweaty palms, and heightened alertness around the desired partner (The Neuroscience of Love: What’s Going on in the Lovestruck Brain? - Georgetown University). It creates the physiological aspects of excitement – the fluttery “butterflies” and pounding heart when you’re near someone you’re attracted to. Norepinephrine, along with dopamine, gives infatuation its energetic, euphoric feel.

Prolactin: Prolactin is best known for stimulating milk production in postpartum women, but it also spikes in both men and women right after orgasm. It has been implicated in sexual satiety and the refractory period (especially in men, who cannot ejaculate again for a time while prolactin is elevated). Prolactin may induce a sense of contentment and bonding; interestingly, some studies link higher prolactin release post-orgasm with greater emotional satisfaction. In men, chronically high prolactin (as seen in certain medical conditions) causes reduced libido, reinforcing the idea that prolactin’s normal function after sex is to signal “enough for now.” It might be nature’s way of enforcing a break between rounds and, potentially, encouraging pair bonding by focusing attention on the just-concluded encounter rather than immediately seeking a new one.

Progesterone: Apart from its role in the female cycle (discussed above), progesterone can have a generally calming, libido-dampening effect. Some research finds that on days when women’s progesterone is highest, their interest in sex (especially with new partners) is lowest (Hormonal predictors of women's extra-pair vs. in-pair sexual attraction in natural cycles: Implications for extended sexuality - PubMed). Progesterone is elevated during pregnancy as well, which may contribute to the often reported decrease in sexual desire in late pregnancy. In men, progesterone is present in low levels and can counterbalance testosterone to a degree (progesterone has anti-androgen effects), though its direct influence on male sexual behavior is less pronounced.

Endorphins and Endocannabinoids: These are the brain’s natural opioids and cannabis-like chemicals. They surge during sexual activity, especially at orgasm, contributing to feelings of bliss and pain relief. Endorphins likely help produce the relaxed, loving afterglow following sex. They also reinforce bonding – similar to how they create a runner’s high that makes one enjoy running with a partner, they make physical intimacy feel emotionally warm and rewarding, strengthening affectionate ties.

Cortisol: As a stress hormone, cortisol can either help or hurt sexual behavior depending on context. In the context of passionate love, cortisol actually tends to be elevated – researchers have noted that new lovers show higher cortisol, which may simply reflect the “stress” (or excitement) of uncertainty and longing (The Neuroscience of Love: What’s Going on in the Lovestruck Brain? - Georgetown University). This heightened cortisol might amplify arousal in the short term (fight-or-flight response adding intensity to emotions). However, chronic stress and consistently high cortisol can suppress sex hormones and reduce libido. Thus, acute stress may sometimes spice things up, but long-term stress usually dampens sexual interest and performance.

In essence, sexual behavior and pair bonding emerge from a symphony of neurochemicals. Steroid hormones like testosterone and estrogen lay the groundwork by setting one’s baseline arousal and mating drive. Neurotransmitters like dopamine, norepinephrine, and serotonin create the rollercoaster of craving, excitement, and satisfaction. And neuropeptides like oxytocin and vasopressin provide the emotional glue that keeps lovers together. All of these components interact in complex feedback loops (for instance, orgasm triggers oxytocin and dopamine release, which then solidify emotional attachment; bonding with a partner can in turn alter hormone levels like testosterone or cortisol).

Hormonal Fluctuations, Attraction, and Fidelity: Summary of Key Findings

To put it all together, studies show that shifting hormone levels can change how we relate to partners over time:

In women, the menstrual cycle creates natural hormonal variation that affects attraction and desire. During the high-estrogen ovulatory phase, women not only feel more sexual desire but may also experience fleeting attractions to highly masculine or genetically fit men (even if those aren’t their long-term partners) (Women more attracted to masculine mates during ovulation) (Hormonal predictors of women's extra-pair vs. in-pair sexual attraction in natural cycles: Implications for extended sexuality - PubMed). This is accompanied by subtle changes in behavior and appearance that make them more attractive to men (The Stripper's Secret | Psychology Today). After ovulation, when progesterone dominates, women’s focus swings back to nurturing their existing relationship, with increased in-pair desire and decreased extra-pair interest (Hormonal predictors of women's extra-pair vs. in-pair sexual attraction in natural cycles: Implications for extended sexuality - PubMed) – a hormonal shift that favors fidelity and bonding.

In men, life history and social context influence hormones in ways that alter sexual behavior. Young single men or men in new passionate relationships tend to have higher testosterone, which supports strong libido and competitive mate-seeking behavior. Once a man commits to a long-term partner or has children, testosterone falls on average (Testosterone Levels Are Negatively Associated with Childlessness in Males, but Positively Related to Offspring Count in Fathers | PLOS ONE). This biochemical shift can reduce his inclination to seek other mates and increase his involvement in parental care. If testosterone stays extremely high, it can sometimes manifest in continued strong mating effort and risk of infidelity (Higher testosterone levels linked to a higher probability of infidelity in men, study finds); if it drops very low, sexual interest can flag. Thus, an optimal balance helps a man remain sexually responsive to his partner but not constantly driven to pursue new ones.

For both sexes, the moments of deep bonding – sexual intimacy, childbirth, affectionate contact – provoke oxytocin and vasopressin releases that strengthen attachment (The Neuroscience of Love: What’s Going on in the Lovestruck Brain? - Georgetown University). These hormones, acting in the brain’s reward centers, make partners feel secure and valued, and even subconsciously discourage straying by making alternative partners less appealing (Hormone affects distance men keep from unknown women they find attractive: Oxytocin may promote fidelity | ScienceDaily) (Oxytocin enhances brain reward system responses in men viewing the face of their female partner | PNAS). Over time, this biochemical bonding may underpin notions of love, loyalty, and even concepts of monogamous fidelity. (It’s no coincidence that only ~3–5% of mammals form monogamous pair bonds – humans are among them, likely thanks to the evolution of these neurochemical bonding mechanisms (Oxytocin enhances brain reward system responses in men viewing the face of their female partner | PNAS).)

On the flip side, hormonal abnormalities or abrupt changes can destabilize relationship dynamics. For instance, postpartum hormonal shifts (high prolactin, low estrogen/testosterone) can reduce new parents’ sex drive for a while, which is natural but can strain a couple’s intimacy if not understood. Likewise, artificially altering hormones – say, anabolic steroid abuse in men (skyrocketing testosterone) or certain hormonal contraceptives in women (blunting the normal estrogen fluctuations) – can change patterns of attraction and libido. Some women on hormonal birth control report more stable mood and libido but less cyclical peak of sexual interest; interestingly, some studies suggest the pill might reduce the mid-cycle attraction to “alpha” traits, potentially even influencing partner choice (there’s debate here, but it’s a fascinating indication of how finely tuned the hormone-attraction link is).

Conclusion: The Chemistry of Sexual Attraction and Love

Modern science leaves little doubt that our most intimate behaviors are deeply influenced by biology. Testosterone and estrogen lay the foundation by energizing sexual desire (generally higher in men due to testosterone, but present in women as well) (Testosterone and sexual desire in healthy women and men - PubMed). These “lust” hormones attune us to seek out partners and initiate sexual activity. Once attraction sparks, neurotransmitters like dopamine and norepinephrine create the exhilaration and focus of romance, while low serotonin adds a touch of obsession that keeps the new lover in mind. If a bond forms, oxytocin and vasopressin begin to weave trust, attachment, and loyalty into the relationship, promoting caregiving and fidelity (The Science of Love | Infographics). Over the long haul, this hormonal choreography encourages pair-bonded couples to stay together, cooperate in raising children, and resist outside temptations – behaviors with clear evolutionary advantages.

It’s important to note that hormones do not rigidly determine our actions – human behavior is flexible and influenced by experience, culture, and individual choice. However, hormones set the stage by biasing our drives and feelings. They make certain outcomes more likely (e.g. feeling horny, falling in love, bonding with a baby) at certain times. Neurobiologically, love and sexual attachment feel magical because they are backed by a potent neurochemical reward system honed by evolution. As one review neatly summed up: testosterone and estrogen spark lust, dopamine and related chemicals fan infatuation, and oxytocin/vasopressin cement attachment (The Science of Love | Infographics). By understanding these hormonal influences, we gain insight into why we might feel particularly attracted to our partner at one time but distracted by others at another time, or why a cuddling session can soothe relationship tensions. In short, our hormones work behind the scenes to connect sex with emotion – driving us toward partners, binding us together in love, and ultimately ensuring the continuation of our species through pair bonding and cooperative parenting.

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