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How the Brain Falls in Love

Kalyn's picture


Kalyn Schofield
Paul Grobstein
Biology 103
Web Paper #2
How the Brain Falls in Love
The biology of love is far too complicated to fully explain, as science has still not found every single possibility for the attraction between a man and a woman. What has been discovered is the process the brain goes through within the body when a man or a woman selects a mate. All these chemical processes within the brain reveal that the real “chemistry” behind the attraction people feel when they fall in love is mainly biologically based.
From an evolutionary standpoint the brain in love for long term relationships functions at three different levels. According to Dr. Helen Fisher these sections are called “sexual arousal,” “romantic attraction,” and “emotional bonding.” Each is responsible for the one of three love type feelings experienced when meeting a potential long term mate of the opposite sex. These feelings are regulated through the brain’s use of various chemicals. The chemical cocktail to stimulate long term long commitment involves the use of each section. Although we benefit from finding a long term mate for a monogamous relationship when all three sections are activated this often does not happen. “While these brain circuits and emotions work with each other in a safe and fulfilling love relationship, they can and do function independently of one another. You can be bonded with one person, infatuated with another and have sex with yet a third person” (Schaeffer, pg 27). This concept is known as the three –brain system theory. The premise of this theory is that there are three parts of the brains of humans have evolved along with the brain of previous animal ancestors. Meaning human brains are not “more” advanced than other animals, we’ve simply constructed a brain that functions on three different levels. These aspects of the human brain account for the diversity in attraction cues and how they vary from person to person when selecting a single mate.
The feeling of love in general has four overall phases that correspond to specific chemical reactions that take place within the brain. These phases of love include attraction, infatuation, commitment and detachment. Attraction is associated with sight and indeed the image of an attractive person has a powerful effect on the brain. “The chemical that results from physical attraction (or lust) is phenyl ethylamine or PEA. It is a naturally occurring amphetamine substance from within the brain that stimulates and increases physical and emotional energy. The initial attraction between two individuals causes one to produce more PEA which results in those dizzying feelings associated with romantic love. Another substance that is released by PEA is dopamine. This chemical increases a desire to be physically close and intimately connected. When these chemicals are being secreted in larger doses, they send signals from the brain to the other organs of the body. If you wonder why you or someone is attracted to the "wrong" person, it may be because you are high on the physical response to these substances, which overwhelm your ability to use your head and exercise "good judgment and common sense” (True Love and Chemistry). Attraction is so powerful that it can lead to long lasting relationships. Additional research done by social psychologists found evidence to support the theory that signals from the body can affect a person’s feelings of attraction for another. Psychologists Donald G. Dutton and Arthur P. Aron conducted three experiments which found a direct correlation between strong levels of anxiety and attraction. Male passersby’s were contacted either on a fear-arousing suspension bridge or a non-fear arousing bridge by an attractive female interviewer who asked them to fill out questionnaires. Results found that more anxiety was produced during the experimental bridge but not on the control group. This showed that attraction was heightened under anxiety provoking circumstances and these heightened feelings can be misdirected to the most suitable target.
Infatuation has often been associated with being drugged or intoxicated. This feeling is largely justified through the chemicals of dopamine. PEA is the substance that releases dopamine and when we fall in love our brain sends signals for more dopamine. This occurs because PEA is responsible for increasing the speed that information between nerve cells. The effects of dopamine leave a person feeling wonderfully happy. These feelings are attributed to the commonly quoted “butterflies” or “weak in the knees” feeling people state when around a loved one. “In a study published in 2002, anthropologist Helen Fisher recruited 40 young people madly in love - half with love returned, the other half with love rejected - and put them into an MRI with a photo of their sweetheart and one of an acquaintance. Each subject looked at the sweetheart photo for 30 seconds, then - after a diversion task - at the acquaintance photo for another 30 seconds. They switched back and forth for 12 minutes” (Helen). The results of this study found that the photos of a person’s sweetheart generated the distribution of dopamine into other areas of the brain including the posterior dorsal caudate and its tail, which are both central to the brain’s system for reward and motivation. When dopamine levels are high the feeling of falling in love is swift and intense causing an obsession to occur with the individual who delivers that feeling. This rise in dopamine explains why some people crave the feeling that a loved one gives them.
The attraction and desirable feelings of infatuation can only last so long before you must decide to committee to your partner or not. Commitment goes back to our ancestral urges as a species to procreate and sire healthy young. The most primitive parts of the human brain have been mainly associated with reproduction. This need to reproduce is an innate drive to procreate and carry on genes. “As far as your genes are concerned, your principal job while you're alive is to conceive offspring, bring them to adulthood and then obligingly die so you don't consume resources better spent on the young. Anything that encourages you to breed now and breed plenty gets that job done” (The Science of Romance). This certainly held more truth back during the age of our human ancestors who often had shorter life spans and less resources than we do now. By having two caregiver’s offspring increase their odds of survival dramatically then if there was only one provider. Males have a biological drive to procreate with many fertile partners. This serves their purpose by continuing their genes through healthy babies. This drive is a direct instinctive to procreate and can be fulfilled without any amorous feelings involved. On the opposite end, women serve as the primary caregiver for any children they bring into the world and therefore most take great caution in selecting a mating partner. A good partner will serve as a provider and caregiver to her and the child. This is important since females will only be able to produce so many children throughout their lives. These instinctual drives that are unique to men and women motivate their selection in a partner. Over time men and women have developed specific biological cues that have enabled them to properly select a desirable mate. Today this ritual of selection is referred to as “romance” and the corresponding feeling is known as “love.” The changes of today’s society have recreated the surface level needs of commitment with humans. People now spend an extraordinary amount of time with the rituals of love rather than the actual process of conceives babies. Therefore commitment has always been an evolutionary essential for conceiving healthier offspring but the changing desires of society today have yielded different reasons for how and why people decided to commit to one spouse.
The chemical found in the brain which generally influences commitment is present for both men and women but effects the sexes differently.  Men are wired with testosterone, which in high levels, actually keeps a man from wanting to settle into a single commitment with one female. Studies have consistently found that low levels of testosterone can positively influence a male’s demeanor’s interest in commitment. For females commitment is linked with the chemicals oxytocin and vasopressin. Oxytocin strengthens the bond between individuals. This hormone is also responsible for the initial bonding that occurs between a mother and child after birth. Vasopressin is a hormone that strengthens attachment between two individuals. Through research with prairie voles the significance of this hormone for love was discovered. Prairie voles are noted for their behavior in mating and forming attachment. Prairie voles have been noted to mate for purposes other than reproduction and they form exclusive pair bonds with their mates. A study done by neuroscientist Larry Young found a direct effect exists between pair bonding and the release of brain hormones oxytocin and vasopressin “When prairie voles have sex, two hormones called oxytocin and vasopressin are released. If the release of these hormones is blocked prairie voles’s sex becomes a fleeting affair like that normally enjoyed by their rakish montane cousins. Conversely, if prairie voles are given an injection of the hormones, but prevented from having sex, they will still form a preference for their chosen partner. In other words, researchers can make prairie voles fall in love or whatever the vole equivalent of this is with an injection. A clue to what is happening and how these results might bear on the human condition was found when this magic juice was given to the montane vole: it made no difference. It turns out that the faithful prairie vole has receptors for oxytocin and vasopressin in brain regions associated with reward and reinforcement, whereas the montane vole does not” (Oxytocin). If human brains resemble prairie voles we can understand the chemical mechanics of oxytocin and vasopress which creates the tendency for humans to form exclusive monogamous relationships. 
The reality of love is not all couples stay together. When this happens the brain has to detach itself from the love interest, process the split in the relationship and prepare for a new romantic interest. Losing a loved one is never easy no matter what the reasons are be it death, divorce, or break-ups. The happy chemicals we experienced during love are now unfulfilled as we do not see our loved one anymore. This causes panic, erratic behaviors and sometimes physical pain. “Over activity in the limbic brain has been associated with depression and low serotonin levels, which is why we have trouble sleeping, feel obsessed, lose our appetites, want to isolate ourselves and lose the joy we have in life. A deficit in endorphins, which modulate pain and pleasure pathways in the brain, also occurs, which may be responsible for the physical pain we feel during a breakup” (Amen, pg 68). A study done in December 2004 found that the brain region activity in specific areas of the brain decrease significantly when participants were experiencing recent grief caused by the thoughts of an ex-lover. Subjects included nine women who had experienced relationship break ups in the past four months (Najib et al.).
If the mind and body are responsible for affecting the level of love one feels for another are people helpless to stop the onslaught of chemicals that dictate their interest in a person? “In addition to being a many splendored thing love is driven by the context. Traits don't seem to jump out in isolation during real, social interaction. By analogy, imagine I ask you whether you like eggs, and you say no. Does that mean you will prefer cake made without eggs? No, you evaluate the cake as a whole”(Access). People and scientists have come up with specific qualities to look out for in a potential mate but these qualities only serve as general guidelines. When faced with real life interactions these guidelines are altered and even disregarded completely. Scientists feel women desire a man with plenty of resources that will ensure the females protection and that of her offspring. Modern women often cite educated and considerate men as positive mate qualities. Men are often seen as biologically seeking attractive and faithful women. Their looks signify good genes for reproduction while their faithfulness ensures the husband his resources will not go to waste on another man’s child. Modern men often emphasize the looks of their partner as advertisements sexualize the body of females suggesting that good looking women are attainable to the most successful men. Instead these generalized attitudes towards mate selections fall short in accuracy. The truth is people may be attracted to certain biological cues from the opposite sex but their selection of an ideal partner is composed of various factors that don’t always rely on chemistry. Experiments using speed dating were done to assess the different cognitive processes people use when selecting a mate.” Based on undergraduates' self-reports of mate preferences for various traits and self-perceptions of their own levels on those traits, It was concluded that modern human mate choices do not reflect predictions of tradeoffs from evolutionary theory but instead follow a “likes-attract” pattern, where people choose mates who match their self-perceptions. Therefore, reported preferences had not corresponded to actual mate choices which were more relevant from an evolutionary perspective” (Different Cognitive Processes). One can see that in general, understanding the biological necessities behind love gives insight into the human species and the complexity between our instincts and impulses. There is no magical answer that allows one to “create” love between two people. Women and men both send and respond to all sorts of biological cues from the opposite sex and these cues can trigger feelings of attraction. Love is complicated but so are human beings and our needs as a species.
Works Cited
Access : Love: You have 4 minutes to choose your perfect mate : Nature News." NaturePublishingGroup : science journals, jobs, and information. Web. 06 Nov. 2009. <;jsessionid=B09A6D5D5D0CCF688641A6D059AD2204>.
Amen, Daniel G. Md. Sex on the Brain 12 Lessons to Enhance Your Love Life. New York: Three Rivers, 2008. Print.
Amen, Daniel G. The Brain in Love: 12 Lessons to Enhance Your Love Life. Three Rivers, 2009. Print.
Different cognitive processes underlie human mate choices and mate preferences — PNAS."Proceedings of the National Academy of Sciences. Web. 06 Nov. 2009. <>
Fischer, Helen, Arthur Aron, and Lucy L. Brown. "Romantic Love: An fMRI Study of a Neural Mechanism for Mate Choice." Journal of Comparative Neurology 493: 58-62. Print.
Helen. "Romantic Love: An fMRI Study of a Neural Mechanism for Mate Choice." N. pag. Print.
Najib, Arif, Effrey P. Lorberbaum, Samet Kose, Daryl E. Bohning, and Mark S. George. "Regional Brain Activity in Women Grieving a Romantic Relationship Breakup." Am J Psychiatry 161 (2004): 2245-256. Print.
"Oxytocin, chemical addiction and the science of love." Oxytocin . org : the biology of true love. Web. 06 Nov. 2009. <>.
Schaeffer, Brenda. Is It Love or Is It Addiction? Hazelden, 2009. Print.
"The Science of Romance: Why We Love - TIME." Breaking News, Analysis, Politics, Blogs, News Photos, Video, Tech Reviews - Web. 06 Nov. 2009. <,9171,1704672,00.html>.
"True Love and Chemistry: Exploring Myth and Reality." ENotAlone Relationship advice and articles. Web. 06 Nov. 2009. <>.



Collin wilkeu's picture


I like this a lot very well written I'd be interested to read your opinion about anything else.

Paul Grobstein's picture

love is mainly biologically based?

"the real “chemistry” behind the attraction people feel when they fall in love is mainly biologically based"

I'm intrigued by the "mainly."  What else is there? 

"modern human mate choices do not reflect predictions of tradeoffs from evolutionary theory but instead follow a “likes-attract” pattern, where people choose mates who match their self-perceptions."

Is a "likes-attract pattern" not "biologically based"?  If not, in what else is it based?