The Reasoning of Love

A few months ago my roommate went through his first college breakup, and the first breakup in his entire life. He was devastated. Clearly he wasn’t the one who wanted things to end. For weeks he would come home distraught, angry, sad, all while his ex moved on with her life and ultimately found someone else. In a fit of pique, my roommate put it to me straight one night, “she is not happy now.” Confused and slightly amused at his point, I asked him how he knew for sure. “If she isn’t with me, she won’t be happy. I know she still loves me.” At this point I sat there searching his face for hints of sarcasm. After finding none I paused before replying, “Well, you can’t force someone to feel an emotion. Happiness or love, at the end of the day it will always be her choice, not yours.” And just like that, the perfect research question revealed itself to me. Is love an inherent choice that we make? Do we really choose the people we love? From my roommate’s case, it is can be argued that his ex made the active choice to stop “loving” him and moving on while he continued to “love” her even when he knew that she had found someone new. It seems to me that it wasn’t that simple. Love is this concoction of reasoning from our genetic encoding, environment, and place in life.

Evolutionary psychology dictates that we do not choose the people we fall in love with. It is a discipline of psychology that attempts to explain psychological traits as the functional products of natural selection. Evolutionary psychologists such as Satoshi Kanazawa and Alan S. Miller have dedicated their lives to the understanding why certain people are more attractive in our eyes than others. Particular aspects of the body are key identifiers of fecundity in females, and even the genetic makeup of both genders. Perhaps my roommate felt the sensation of “love at first sight”, a phenomenon that can be explained through the idea of finding someone who will help you produce healthy offspring.

Symmetry and Aesthetics:

Facial symmetry and lack of blemishes have always been a reference towards health, stature, running speed, and intelligence. Bilateral symmetry negatively correlates to pathogens and parasites within the mate. Facial averageness is also an important factor in determining that the genetic makeup of an individual is diverse. When genetic variety can reduce the chance of birth defects and disabilities by up to 30%, we as humans can’t help but constantly look at our world for perfect symmetry.


Smell and Fertility:

A person’s smell is a gross simplification of detecting someone’s pheromones, a type of scent-bearing chemical secreted in sweat and other bodily fluids. A type of pheromone called a “releaser” contains the compounds androstenone, androstadienone, and androstenol. According to the American Chemical Society, these compounds have been shown to be involved in sexual attraction. Bettina Pause, a psychologist who studies these pheromones, told Scientific American that, “a lot of our communication is influenced by chemosignals.” Numerous studies on shirts that both men and women have slept in have substantiated this claim on physical attraction based on smell. But for women, this gets more interesting.

Men can actually sense fertility in a women’s menstrual cycle. Research done at the University of Texas at Austin took the shirt test one step further by testing the smell of the t-shirt at every point of a woman’s menstrual cycle and asking men to assess which ones they found more “pleasing”. When the results were tallied up, the shirts worn by the fertile women were found to be more “sexy” and “pleasant.”

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A third and separate experiment was done by the University of Liverpool, University of Newcastle, and University of St. Andrews to determine if female facial attractiveness increases during the fertile phase of the menstrual cycle. Their study involved over 180 participants from both genders. When presented with two photos, one during the follicular phase (fertile, 12 days) and one in the luteal phase (19 days) there was a 51.9% change that a male would choose the photo of the woman in the follicular phase over the photo of the same woman in the luteal phase. This almost 2% increase in “attractiveness” around the time of ovulation could potentially lead (or have lead) to reproductive benefits for females in two ways: it could enlarge the pool of potential mates, or it could act more specifically as a fertility signal that is detectable only by long-term partners.

Kindness and Character:

Harvard professor, Steven Pinker, states that “We are able to judge people’s characters from their faces – whether they are honest, kind, and even their intelligence.” We can’t help but want certain personalities as our significant other. It is through certain similarities within the other person’s personality that we feel inherently more attracted to our loved ones. This is what’s known as the theory of positive assortative mating. This theory promotes the idea that humans want comparability with chosen mates in order to foster a positive environment where their offspring can thrive. Not only that, this level of similarity allows for complementation in the genetic code of offspring.

Eyes and Age:

When looking at eyes, women’s in particular, large eyes are a sign of youth. Eyes fully develop at the age of seven and since they do not grow in size relative to the rest of the body, babies often look like they have larger eyes than adults. A person with large eyes is therefore more likely to be mistaken to be younger than he or she really is. Youth is an extremely desired trait for females due to the anatomy of the female body and the limited number of fertilizable eggs a female has in one lifetime. The younger the female, the higher number of fertilizable eggs left within her body.

Waist to Hip Ratio and Spinal Curve:

A woman’s waist to hip ratio is highly determinant of how attractive she may appear to men. The optimal ratio of 0.7 has been shown to be the most attractive, an indicator of good child bearing hips. Studies done by the NorthEastern Evolutionary Psychology Society have found that when men were shown naked images of women in upright poses from the front or back, these men rated women with a 0.7 waist to hip ratio as most attractive. What’s more interesting is how greater wedging in the lower half of a woman’s spinal curve draws a male’s attention. This spinal structure would have enabled women to be more effective at balancing their weight during pregnancy and therefore less likely to suffer injuries during pregnancy.

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Through these many pre-determined factors that appeal to our evolved mindset of beauty, it seems that the obvious answer to whether or not love is a choice is that it is not. Evolutionary psychology has proven on multiple accounts on why certain people just appear more attractive to others initially. Their level of attractiveness was not a conscious decision made by people, but rather generations of natural selection. However, to put evolutionary psychology to the final test of seeing if initial attraction can lead to a healthy marriage, we must dive into the study of spouses of identical and fraternal twins. If the arguments made by evolutionary psychologists are true, then people sharing the same genetic code and environmental upbringing should have spouses who are similar in many regards.

A Twin Study of Mate Selection

As an Engineering Mathematics & Statistics major, there is nothing more I would like to see than a mathematical algorithm that has collected billions of data points to see where the correlations of evolutionary psychology and the human emotion of love lie. But as of right now, I do not have that information. An in-depth study of twins, however, is a favorable alternative.

The Similarity Model of Twin Mate Selection:

Whether the idea of mate selection is rationally or emotionally intuitive, we can assume that there are certain characteristics of the chosen mate that will be related to those of the chooser. This continues the idea of positive assortative mating, that we select mates similar to ourselves. In order to test the validity of this theory of mating, the University of Minnesota Graduate School conducted a survey of 901 pairs of married twins. This survey was so thorough it was even completed by 133 pairs of the parents of the younger participant twins to see if opinion was carried through genes or environmental influence. The 40 items that were asked for similarity ranged from carpentry, cooking, singing, athletics, buying and selling to public speaking ability, and so on and so forth. The survey included both identical twins (marked as MZ) and fraternal twins (marked as DZ). The conclusion was that MZ spousal correlations were the highest and DZ in second and third for overall correlation. //see Table 2. In other words, this study supports the theory of positive assortative marriage. Since spousal correlation is greater than fraternal twin correlation, we see that certain personality traits and interests may stem from genetics rather than the environment.

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Education serves as another indicator of the kind of mate a person will choose. A study done by Jeremy Greenwood from the University of Pennsylvania continues the argument for positive assortative mating. Based on his data, there is an apparent direct correlation between who a person chooses to marry and their level of education.

  1. a) Poverty or Last Chance Model

So far in this discussion on choice, the assumption was made that mate selection did not have any socioeconomic hindrance. A proper analogy would be like choosing clothes off a rack. But most of us do not have that many choices. A. C. Kerckhoff pointed out, “Many of us only know people in our neighborhood, church, school, and most of those people resemble us enough because of the ethnic and social stratification that these institutions naturally impose.” This poverty model line of thinking suggests that there may be only one mate who is “available”. The man asks the woman out in this case because she’s there and looks to be available and she accepts because he is the only one who’s asked her. This single-option situation prevailed during the Pleistocene era, when humans lived in small bands and between-band contact was rare. However, the similarity model has not been able to account for actual choice among twins, and people at large, due to modern dating technology and social mobility. The modern era has ushered in a plethora of choice, no matter the socioeconomic status.

Aziz Ansari addresses the idea of the one choice model (either because of lack of options or location) and arranged marriages in his book, Modern Romance. Most marriages of this sort start off as companionate marriages, where a person finds someone with whom a family could be formed together. Love was seen as a luxury in this case. Stephanie Coontz, author of Marriage, a History, said that, “Marriage was too vital an economic and political institution to be entered into solely on the basis of something as irrational as love. Women wanted financial security. Men wanted virginity and weren’t concerned with deeper qualities like education or intelligence.” One might assume that these types of marriages were then “loveless”. Ansari quickly proved otherwise. He states, “Couples often developed increasingly intense feelings for each other as they spent time together, growing up and building these families. These marriages may have started with a simmer, but over time they could build to a boil.”

Twins’ Evaluation of Their Cotwins’ Choices

Based on what evolutionary psychology has proven about the science of attraction, a reasonable assumption is that a twin will evaluate his or her cotwin’s choice of spouse in a favorable manner. In addition, identical twins should endorse their cotwin’s choice more than fraternal twins do because of their identical genetic code. Genes, as mentioned before, are the backbone of the evolutionary psychology argument: that our genetic encoding determines whom we fall in love with. The study conducted by the University of Minnesota asked twins to report how they felt about the cotwin’s choice of a mate to estimate whether mate selection is about the characteristics of the chooser. The results were surprising.

Identical twins (MZ) tend to be similar in most of their choice behavior, not only by their own report but also through confirmation from their spouses as shown by Table 5. However, when it comes to mate selection there is a surprising amount of disapproval from a twin on his or her cotwin. Only 13% of MZ cotwins stated that they “could have fallen for [the spouse] themselves.” This is an extraordinarily low percentage. Through the hypothesis of evolutionary psychology, people who share identical genes should have similar preferences for mates. Through the hypothesis of positive assortative mating, the spouses’ personalities should match that of the twins and cotwins since the twins’ personalities were near identical. This evidently wasn’t the case as only 10% of spouses said that they “could have fallen for their spouse’s identical twin.

The premise that one chooses a mate that is similar to one’s self has lost its grounding as there is no direct evidence to support it. The similarity model, although true descriptively and in theory, doesn’t seem to account for the affirmative selection of a specific mate. Through this study, one can argue that love is indeed an active choice made by each individual. It has to be, or else the identical twins would have near identical looking spouses who have similar personalities. There shouldn’t be this variation in choice. Indeed, acknowledgments must be made about possible shortcomings of the University of Minnesota study. Since the twin knew that he or she was evaluating his or her cotwin’s spouse, the twin may evaluate the spouse at a much lower score due to the fact that the spouse is the twin’s in-law. We tend not to find family romantically attractive as to prevent There have been numerous studies, both empirical and statistical, on how sexual attraction towards family, even if they were married in, is extraordinarily diminished. Yet this still can’t explain why 37% of the twins looked “disapprovingly” towards their cotwin’s spouse.

Clearly the study on twins does not solve the question of whether or not love is a choice. But that doesn’t mean that this question or method of thought for love is completely novel. Robert J. Sternberg from Yale University puts “choice/commitment” as one of the three pillars that make up the Triangle Theory of Love.

A Triangular Theory of Love

According to this theory by Sternberg, love has three components to it:

  1. Intimacy: feelings of closeness, connectedness, and bondedness.
  2. Passion: drives that lead to romance, physical attraction and sexual consummation. Most closely described by evolutionary psychology.
  3. Choice/commitment: the decision that one loves another, in the short term, and the commitment to maintain that love in the long term.

There have been different models before this Triangular theory. The “Spearmanian” Model describes love as essentially this singularity of positive feelings. The “Thomsonian” Model puts love as a mixture of many different small feelings that, when put together, forms the emotion of love. The “Thurstonian” Model conceptualizes love as three separate feelings that, when combined together, form love. All of these theories serve as predecessors to the Triangular Theory of Love. None of the theories before has done as good of a job at explaining the “choice/commitment” component as the Triangular Model does. For this particular study, the “Choice & Commitment” component will be of major focus.

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Choice & Commitment

The decision to love is the decision to endure the ups and downs of any relationship. This component is essential for getting through hard times and to return to better ones. For most people, this choice results from emotions and intimacy. But it does not have to always stem from passion. This may be a result from not having the choice of partners. One perfect example is love for family. One does not get to choose one’s mother, father, siblings, etc. In these close relationships, love can start off as a decision.


At the conclusion of almost every research article, scholarly paper, and primary source on the topic of love (which there were a surprisingly high amount), the author acknowledges that love is unpredictable. And through all this research, I believe it too. Love is this concoction of reasoning from our genetic encoding, environment, and place in life. Our genetics may determine who is beautiful at first glance, but our eyes can also be deceiving. True beauty comes from personality, trust, and and personal history with another. These intangible aspects are unquantifiable in numerical terms. Take the twin studies for evidence. The argument for genetics and evolutionary psychology falls apart because we are humans. As humans, we are inherently unpredictable and that’s what sparks creation, innovation, and ingenuity. Through our own choices, yes, we can position ourselves to be able to love, but there are so many random factors that make the argument that “love is completely a choice” invalid. Our extenuating circumstances are never quantifiable, and this will always remain true. Though this research has not proven anything as scientific law, it does unveil the science behind love a bit – and this makes love a little less daunting.

“No one falls in love by choice, it is by chance. No one stays in love by chance, it is work. And no one falls out of love by chance, it is by choice.” – Seth Adam Smith

Perhaps your significant other is just one breath of courage away.


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