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Love: More Complicated Than Chemistry

Rica Dela Cruz's picture

For many of us in this world, love appears to be the sole purpose for living. We live to find and experience love and sometimes even die for love. Human beings appear to have a "genetic clock," such that they mature, fall in love with a mate or several mates, and thereafter spend their adult life having children. Like most other animals, humans appear to have an innate purpose to reproduce. Humans, like other animals, repeat this "life cycle" over and over. However, there appears to be one major difference between man and the rest of the animal kingdom in this life cycle. We seem to make this life cycle even more complex than it really is. It is because of the way in which we love that causes this complexity.

Why do we "act crazy" and do stupid things that we would not ordinarily do whenever we see an attractive mate? What is it that makes us beings get "all fluttery" when we see a potential mate? And is the practice of having only one mate for the rest of their life "unnatural?" Is monogamy simply a practice imposed by religion? Love is one of those things in life that we simply take for granted, but can never fully understand, at least so far.

Only recently have scientists begun to study the causes for love. It has been found, for example, that certain regions of the human brain are activated and various neurotransmitters are released when a person is in love. Functional MRIs (fMRIs) have shown that certain areas of the brain are activated when a person is in love. These areas that are activated include regions of the cortex, such as the medial insula, anterior cingulated, and regions of the sub-cortex, such as parts of the striatum and nucleus accumbens. Scientists have found this very interesting because it is these areas of the brain, which constitute the core regions of the so-called "reward system." Thus, when a person falls in love, these areas of the cortex and sub-cortex become activated and allow the person to feel happiness and satisfaction. One particular neurotransmitter that causes a person to feel happy when in love is dopamine. Dopamine is released by the hypothalamus and puts a person in a "feel good" state [1].

It is obvious that falling in love and being in love make people happy. But it seems to also make people act strangely and do things they ordinarily would not do. The state of being in love appears to "transform" people's behavior and makes them do things that are sometimes noble and heroic, and sometimes wicked and evil. For example, Romeo and Juliet died for each other, because they were not permitted by their family to love each other.

Recent fMRI studies have shown that love does not only increase activation of the romantic core, but also decreases the activations, or inactivates, areas of the cortical zones, which include the frontal and parietal cortexes and amygdala. The amygdale, for example, is known to be engaged during fearful or scary situations. The frontal cortex controls judgment and the parietal cortex have been found to be involved in negative emotions. Therefore, when one sees the person they love, any fear they may have decreases due to the inactivation of the amygdala, their judgment is blurred due to the inactivation of the frontal cortex, and they have less negative emotion due to the inactivation of the parietal cortex area [1]. As a result, people in love do not think in the same way that they would in a "normal situation." A person in love feels he is capable of doing anything. Many times people do things irrationally when they are deeply in love. It is apparent, then, the expression "love is blind" may actually be true.

Thus, love is an emotion makes a person appear crazy or irrational. The suspension of judgment produced by falling in love could lead to a state that others would interpret as madness or being insane. One study has shown that people who have recently fallen in love have exhibited some of the symptoms of obsessive-compulsive disorder (OCD). This appears to make sense because during the early stages of love, a decrease in the presence of the neurotransmitter, serotonin, has been found and OCD is known to be associated with low levels of serotonin [2].

A particularly interesting apsect about humans being in love is that society views monogamy as the accepted way of life for humans. Because of this social value imposed by society, most humans are taught that they should love, marry and have children with only one person. But this social norm has an exception of sort: through separation or divorce, and then remarrying. One explanation for society placing such importance on monogamy is that the children would be best served if both parents are involved in raising them [4]. The other reason, of course, is religion. Christianity in particular has sanctified monogamy and made polygamy a sin. This reason, however, does not answer the fundamental question: Is man by nature monogamous?

One study has been done on prairie voles in order to better understand the reason for monogamy and whether humans are true monogamists. Prairie voles are a type of rodent that only has one mate during their lifetime. A male will not mate with another female whom they did not lose their virginity to and both genders will not reproduce again if their mate dies [4]. Studies on these rodents have shown that the hormones, oxytocin and vasopressin, are released when prairie voles have sex. Oxytocin and vasopressin are involved in attachment and bonding between individuals and are linked to dopamine, which is associated with reward. When these two hormones are blocked in prairie voles, they become promiscuous. If injected with the hormones and prevented from having sex, they are faithful to their partners. However, receptors must be present for the hormones to act. In prairie voles, oxytocin and vasopressin are highly abundant in the reward areas of the brain in the sub-cortex. One may think that if polygamous animals were injected with oxytocin and vasopressin, they too may become faithful to only one partner, but this is not the case because they do not have these receptors present in the reward centers of the brain [1,3].

Studies on prairie voles have been used to explain human monogamy because humans also release these hormones. However, there is still no evidence that they work in the same way because the human brain is a lot more complex than the prairie vole brain [1]. I believe it would be interesting to know how these monogamy-inducing hormones work in humans because humans sometimes do not seem to have the same type of commitment to monogamy that all prairie voles appear to exhibit. There are so many cases of humans reproducing again after a partner dies; or having more than one sexual partner at a time through infidelity, adultery and prostitution.

Is there a chemical or biological reason why certain people cannot remain monogamous? One possible reason could be that each person has a different level of oxytocin and vasopressin present in their system; and further, that each person has different amounts of receptors present in the reward areas of human brain. But try telling this to your spouse and you'll be sleeping in the doghouse.

Love, indeed, can be one of the most wonderful experiences in life. However, it is an outgrowth of the most complicated organ in man: the human brain. The reason why we love and why we act the way we do when we are in love may continue being a mystery, even as we start to study scientifically "what makes man tick." It seems for now that we only know that we are in love when we experience and feel it. As Emily Dickinson succinctly stated:

That Love is all there is,
Is all we know of Love.



1. Zeki, S. "The Neurobiology of Love". FEBS Letters. 12 June 2007. Vol 581, no 14, pp 2575-2579.

2. "The Science of Love". BBC. 18 November 2004. 4 April 2007. <

3. "Love and the Brain". Society of Neuroscience. December 2005. 4 April 2007. <

4. Than, Ker. "Wild Sex: Where Monogamy is Rare". Live Science. 20 November 2006. Imaginova. 4 April 2007.



Paul Grobstein's picture

the brain and love

Nice to have Dickinson on this subject too. But if she's right about the brain, then there is more to know of Love than the experience. There's the brain. And maybe from that we can acquire an ability to act less "insanely"? That seems to be the direction the work is going?