Love is the core of our human experience. Throughout history, love has been the motive behind war and peace, acts of madness and grace. It has inspired countless folk tales, novels, songs and other works of art. But what drives this intense emotion? One that can “launch a thousand ships” as in the Trojan War or drive “two star-crossed lovers” to move to the next life when their union was forbidden in this one. The answer might not be as serendipitous as we think and lies in a vast, interconnected network of nerves, chemical signals and organ systems in our bodies — a network whose parts are in constant communication, showing us that love is truly poetry in motion.
Not all love is created equal — the way that we feel about our partners early in a relationship often changes and deepens over time. The love between a mother and child is vastly different than one between romantic partners. Anthropologist and human behavior researcher, Helen Fisher, Ph.D., breaks down romantic love into three types: lust, attraction and attachment, each of which are controlled by separate hormones, nerves and parts of the brain. Lust is driven by our evolutionary desire to pass on our genetic material, ensuring the continuation of our genetic line and, in turn, the continuation of our species. When visual, olfactory, tactile and chemical cues draw us to a potential partner, a part of the brain, called the hypothalamus, sends powerful chemical signals to our testes and ovaries to release testosterone and estrogen. Both can be found in men and women and promote sexual urges, with testosterone being the strongest driver of libido. Several studies have shown that men and women with higher circulating levels of testosterone engage in more sexual activity. Women also tend to report more sexual desire around times of ovulation when estrogen levels are at their peak and testosterone activity increases. As testosterone declines with age, libido usually follows suit (giving rise to a burgeoning hormone replacement industry). Simultaneously, the hypothalamus also releases the neurotransmitter, dopamine, a powerful, chemical signal made inside neurons. Dopamine is referred to as the “feel good” neurotransmitter and stimulates the parts of the brain associated with desire, reward and addiction. It is released during activities that give us pleasure including exercising, spending time with friends and family, and engaging in sex. From an evolutionary standpoint, the feedback mediated by dopamine reinforces behaviors that ensure our survival like staying fit, staying secure using “safety in numbers,” and producing offspring.
Have you ever been so in love with someone that you could not sleep or eat? Has the thought of that person been so consuming that you could think of little else? If so, you may be in the phase of love known as attraction or the “love struck” phase. In this phase, the hypothalamus continues to release dopamine to the reward center of the brain, reinforcing the pleasure we feel when we spend time with and think about the person we love. Does your special someone ever give you butterflies in your stomach or make you feel giddy? Do you ever get sweaty palms before a big date? Our adrenal glands are at play, releasing large doses of norepinephrine (aka noradrenaline) which are also involved in our “fight-or-flight” response. Norepinephrine travels in the bloodstream and binds to receptors throughout the body, leading to feelings of excitement, euphoria, racing heartbeat and perspiration. There is also a simultaneous depletion of the neurotransmitter serotonin which is responsible for reducing appetite and interfering with sleep. In fact, studies have shown that the level of serotonin in the brains of those in the early stages of romantic love can resemble those of people with Obsessive Compulsive Disorder. It’s little wonder then that we often become infatuated and almost obsessed with the ones we’ve fallen in love with — almost as if they’ve taken up permanent residence in our minds (and Instagram feeds). We are also suspect to irrational behavior when in love (just ask Romeo and Juliet). Studies have shown that as the parts of the brain which control passion and romantic love increase in activity, the parts of the brain involved in rational thought, judgement and executive functioning decrease in activity. This could explain why we have a tendency to overlook our partner’s flaws and shortcomings and become “blinded by love,” (now, if you could only make your friend see why her new boyfriend isn’t a good fit for her).
Over time, we tend to place less of an emphasis on physical attraction and a stronger emphasis on relationship security, quality time and emotional intimacy. This defines the last stage of love, known as attachment, and is the kind of love experienced between long-term partners, friends and between a mother and her children. In this phase of love, the hormones oxytocin and vasopressin dominate. They are released by a part of the brain known as the pituitary gland and attach to receptors in the brain and throughout the body, promoting a sense of security and bonding while dampening the “fight-or-flight” response — characteristics necessary in promoting intimacy. Women release a surge of oxytocin and vasopressin during childbirth and breastfeeding, while both men and women release it during orgasm — instances where emotional bonding is reinforced.
The three phases of love often act in concert with each other but also independently. For example, we typically lust for the same people with whom we feel an intimate attachment but, for good reason, will stop short when that intimate attachment is toward a family member. We are capable of having sexual relations with those whom we feel no romantic connection (popular dating apps are all too familiar with this concept). Alternatively, men and women can have an emotional attachment to someone with whom they have no sexual desire, aka “The Friend Zone.” Sounds complicated? Facebook has a button for that! But love is not as simple as “In a Relationship” or “Single.” Love’s many forms are mediated by a complex relationship of electrical and chemical signals acting throughout our bodies. If love were a language, then our brains, hormones, neurotransmitters and glands are the words of poetry that bring it to life.
Dr. de Lota is a family medicine physician working at Austin Regional Clinic. He enjoys treating people of all ages and has a passion for preventative care, evidence-based medicine and patient education.