Shakespeare once asked, "What t’is to love?"
I have always been a strong advocate of love. Whenever people have something to do in the name of love, I support them a hundred and ten percent! I’ve witnessed many a love team made and broken – most of the time from the beginning, some still ongoing, others until the end. For someone who claims never falling in love yet, I’m a confessed hopeless romantic.
Throughout history, it was philosophy, religion and art that explored the phenomenon of romantic love. Now, you may be wondering why an article on love is being featured in Star Science because one does not hear the words love and science together often. But in the last century, science has taken part in discussing the nature and function of love. Only recently have scientists tried to define the once ineffable, "another dimension beyond reason" love – a mammalian drive as primal as hunger and thirst, rather than an emotion such as happiness.
Contrary to popular belief that it is the heart that loves, it is actually the brain that does. So which areas of the brain are active when people are in love? Andreas Bartels and Semir Zeki of University College, London located the areas activated by romantic love by measuring the blood level in the brain, thereby knowing its activity or lack thereof. fMRI scans of students who claimed they were madly in love showed that people in love have activity in the caudate nucleus, putamen, insula, ventral tegmental areas, and nucleus accumbens – brain parts associated with the reward system, making it primarily a motivational state to pursue a chosen partner. What is more surprising is that the amygdala, which is primarily linked with emotions such as depression, anxiety and fear, has little or no activity at all. Equally interesting is the decreased activity in parts of the brain involved in moral judgment. There is some truth to the saying "Love is blind" after all.
Studies of Helen Fisher at Rutgers University have shown that three emotion-motivation systems evolved in our brain as we courted, mated, and reared our young: lust, attraction, and attachment. Each stage of love corresponds to a brain system associated with different sets of neural networks and primary neurochemicals. These three systems are independent of one another, meaning each can operate simultaneously. It is possible then that you can be at two or even three stages at the same time, and it may be with the same partner or a different one.
Lust – the craving for sexual gratification from anybody – is primarily associated with testosterone both in men and women. Yes, women, too, secrete testosterone although in minute amounts compared to men. It is produced in the thecal cells of the ovaries and the Leydig cells of the testis. Testosterone, a steroid hormone from the androgen group, can either be converted to 5a-dihydrotestosterone by the enzyme 5a-reductase or to estradiol by the enzyme aromatase. It then binds to its receptor, activating downstream pathways, thereby having either a virilizing or anabolic effect. The former includes enhanced libido, hence increasing the urge for sexual gratification.
Attraction – the elation, heightened energy, obsessive thinking, focused attention, lack of appetite – is the popular romantic love we know of. This is associated with increased levels of dopamine and norepinephrine, and decreased levels of serotonin. Dopamine functions both as a precursor to norepinephrine and a neurotransmitter. It activates the reward system in the brain, providing feelings of enjoyment and happiness and reinforcing motivation to proactively perform certain activities. It is the same system that is linked with addiction to drugs. So, when we say we are addicted to him/her, we really are! Moreover, schizophrenia is a disorder associated with abnormally high levels of dopamine, with symptoms including disordered thought, hallucinations, and social withdrawal – very much the same symptoms as when falling in love. In addition, norepinephrine plays a large role in attention and focus, explaining why we have focused and undivided attention on our loved one. So much so that even though we are doing other things, we still have our focus on him/her. Lastly, serotonin regulates body temperature, sleep, mood, and appetite. A decreased level of serotonin then disrupts our normal sleeping and eating habits. They say we cannot fall asleep when we are in love because finally, reality is better than our dreams. It may be true but mostly it is because of the serotonin. Serotonin is also responsible for the Obsessive-Compulsive Disorder (OCD), explaining our temporary insanity and obsession with our loved one. "Crazy for you" then is not just a song; there is a scientific basis to it. Some scientists then hypothesize that those who actually take anti-depressants, which increase the levels of serotonin, may have less chances of falling in love.
Attachment – the long-term calm and emotional union with a partner to rear a young – is mainly associated with vasopressin (VP) and oxytocin (OT). These two hormones are similar in structure, differing only in the amino acids isoleucine (OT) or phenylalanine (VP) at position 3; and leucine (OT) or arginine (VP) at position 8. Although both contribute to the monogamous bonding of a couple, the protective attitude toward our partner is attributed to the former, while monogamy is associated with the latter. Vasopressin makes us aggressive with potential competitors (i.e., close friend of your girlfriend, best friend of your boyfriend). Next time you wonder why you are so jealous, it’s the vasopressin. On the other hand, in an experiment involving monogamous prairie and polygamous montane voles (short-tailed stocky rodents), the oxytocin receptors in the reward-associated brain region of the prairie voles were shown to be responsible for monogamy; lack of oxytocin receptors in the montane voles then caused them to be polygamous as they had no memory of the other voles they had met. So, when you catch your boyfriend/girlfriend two-timing you, maybe he/she doesn’t have enough oxytocin receptors to be with you alone. Both OT and VP are also related to territorial behavior, as you are with your loved one. In an experiment done by our very own Filipino scientists from the University of the Philippines, Lourdes J. Cruz, Victoria de Santos, Glenn C. Zafaralla, Cecilia A. Ramilo, and Baldomero M. Olivera, in collaboration with Regina Zeikusll and William R. Gray, oxytocin and vasopressin homologs were extracted from Philippine cone snails, namely Conus geographus and Conus striatus, and were intracerebrally injected into mice. A scratching response in the mice, which is a feature of territorial behavior, was observed.
Science isn’t only interested in the upside of love but in its downside as well – rejection. When you love someone, there is always the risk of being rejected. When one is dumped, he/she undergoes two stages: protest and resignation/ despair.
Protest involves obsession with winning your partner back. It is a typical mammalian response to a broken tie, resulting in increased dopamine and norepinephrine that stimulate your asking for help and calling for your loved one. It is indeed paradoxical – very typical of love – that as your darling slips away, the hormones associated with attraction actually increase. It is also possible that delaying the reward system actually prolongs its activities, explaining why you still feel you’re in love. But this delay also has its threshold. When it finally sinks in that there is no chance that your loved one will come back to you, it is when resignation and despair set in. Dopamine levels drop, resulting in lethargy and moping. Depression also sinks in. Some may even be angry, thinking that anger switches off love. But this is not the case since anger and love are independent systems. You can be angry but still be very much in love.
Rejection devastates us in different degrees but time will come when we’ll recover from it and be ready to fall in love again. Bouncing back from rejection is not easy but definitely possible. We make mistakes in life but it is never a mistake to have loved. Never lose faith in love for it is better to have loved and lost than not to have loved at all.
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Richelle Guzman Duque is an undergraduate student at the National Institute of Molecular Biology and Biotechnology of the University of the Philippines-Diliman, Quezon City. She is currently constructing and analyzing the cDNA library of the marine snail Turridrupa cerithina at the Medical Biotechnology and Genome Research Laboratory. She can be reached at richelle314@gmail.com.
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