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Love as an Evolutionary Adaptation

atuttle's picture

By its very nature, love is an irrational and capricious emotion. The Merriam-Webster dictionary defines love twelve different ways (thirteen if you count the tennis term), and there have been countless attempts made by poets, musicians, philosophers, and literary figures to distill and define the essence of this powerful emotion. At first thought, love appears to be too complex and ambiguous to define in a scientific manner. As Professor Le mentioned, social scientists do not attempt to operationalize complex emotions like love in their entirety. For example, by demonstrating love-directed behavior in one instance is a study able to be generalized to other situations? If that were true, dating would be much easier! Similarly, if research is able to definitively show where the “love center” of the brain can be found, does this evidence do the emotion justice? Over the course of this article I would like to review scientific theories pertaining to the evolutionary origins of romantic love before revisiting these questions.

As social science continues to define aspects of romantic love, there is a greater consensus in the scientific community that no two people experience the emotion in exactly the same way. As a complex human emotion, love is the culmination of a complex interplay between biology, cultural, and environmental influences. In spite of individual differences, however, aspects of love appear to be universal. The universality of love indicates that this emotion may be evolutionarily adaptive. Recently, evolutionary biology has attempted to “reverse engineer” complex emotions (including love) in order to determine how these emotions became evolutionarily adaptive. According to Pinker, emotions like love were preserved in human biology because they identify and prioritize goals based on human needs. In other words, emotions appear to be necessary to motivate an individual to accomplish basic tasks, including feeding, fleeing, defending, and reproducing.

How does love act as a source of motivation? Scientists believe that love acts as the emotional mortar which binds individuals to one another in spite of changing circumstances. For example, one seemingly universal correlate of love is empathy, or the “mirroring of complex emotional states in another.” As socially adept beings, humans have developed this ability to determine emotional and sensory states in social peers. This emotional state appears to play a fundamental role in human social interaction. The evolutionary adaptiveness of empathy, however, is unclear. Some argue that empathy evolved in social species as an integral component of altruism, or the set of behaviors that cause an individual to “benefit another…at a cost to [the] self.” (Pinker, 1997).

From an evolutionary perspective, altruism appears to be counterproductive. Dawkins poses an important question: If evolutionary development has been dictated by the “selfish” actions of genes competing for limited resources, why do altruistic behaviors exist? One theory requires that altruism be defined on two levels. Although these actions are selfless on a behavioral level, altruism ultimately benefits the prospects of survival (and reproduction) of the altruistic individual (Dawkins, 1989). For example, familial altruism is thought to have evolved because family members benefit from protecting those who share their genes. Even though the individual may perish, by protecting relatives with related genes a part of the individual’s own genetic material will remain within the larger population’s gene pool. Pinker states that this is the reason why familiar closeness appears to dictate the degree of altruistic behavior between humans. Parents, for example, tend to sacrifice more for their children than for their nieces or nephews (Pinker, 1997).

Typically, when people describe acts of parental sacrifice they attribute the action to “love.” While a mother sacrificing her own well-being for her child may be an altruistic act, she does not shortchange her own state because she is feeling “altruistic.” Rather, she makes the sacrifice because she loves her child. Based on these examples, it appears that maternal (or paternal) love is strong because it correlates with an individual’s genetic survival.

Other forms of love (i.e., “love for fellow man”) also exist within the human experience. Similarly, social scientists attribute these emotions to reciprocal altruism, or the tendency to help a non-related member of a social group. Evolutionary biologists believe that this form of empathy may also increase an individual’s chances of survival. For example, certain species of primates have evolved to groom one another for harmful parasites, even though they are not related. This reciprocal behavior increases the rate of survivability for each member in the collective group by protecting against parasitic disease. As a result, the social trait is preserved in the population (Dawkins, 1989).

Social phenomena like familial and reciprocal altruism only work when constituent members of a community can reasonably rely on one another for reciprocation (Pinker, 1997). Theorists believe that over the course of our evolutionary development, individuals evolved to cheat reciprocal systems. Returning to the example of reciprocal grooming, a selfish individual will spend less time grooming, instead spending more time being groomed by others. It follows that this individual, left unchecked, will benefit from the preexisting social system. As a result, subsequent generations will mirror this dominant phenotype, eventually eliminating empathetic behavior from the population. Because altruism continues to persevere in social organisms, however, there must be a check against individual selfishness. Pinker proposes that social animals have evolved a “cheater-detector” that helps protect the majority of an altruistic group against selfish individuals. This cheater detector allows altruistic members of a social group to judge and punish selfish behavior exhibited by individuals (Pinker, 1997).

In other words, love appears to have a darker side for a reason. Related emotions like jealousy, doubt, anger, and hate may have developed to ensure that members do not break a social contract. In his article Crazy Love, Pinker talks about individuals who commit crimes of passion when they are scorned (Pinker, 2008). While these acts may not appear to be rational or logical, they do make sense when love is viewed as an evolutionary adaptation. Essentially, one possible explanation for the evolution of love is its ability to function as a cheater-detector in social hierarchies.

Further evidence of love’s importance in regulating social relationships comes from autism research. Researchers believe that an inability to empathize (which we have identified as a key component of the love emotional response) may lead to social dysfunction. Specifically, empathy appears to be necessary for proper social interaction because it allows an individual to correctly identify complex social cues. Consequently, the inability to perceive overt social cues exhibited by others leads to difficulty perceiving underlying emotional and intentional states, which in turn upsets the formation of social bonds.

In summary, it appears that love is an evolutionary adaptive emotion because it allows us to maintain relationships with one another. As a highly social species, humans depend on cooperation to survive in our environment. This explanation for love’s presence in the human condition, however, is not meant to be a complete definition of the emotion. As a highly individual experience, the act of loving something or someone is dependent on the individual’s biological, psychological, and experiential development. In other words, while social science is making strides to understand the underlying framework upon which love is based, the end product can still take your breath away. To use an example as a comparison, physics classes often teach students how rollercoasters work to demonstrate basic physical concepts. Students understand that the laws of gravity, the geometry of track angles, breaks, etc. contribute to a rollercoaster’s function, but when they strap themselves into a car it still a unique and indescribably exhilarating experience. It appears that love as an experience may be similar: While common correlates of love may be universal, the emotion is also defined by the complex interplay between biology, cultural and environmental influences, and the way that we choose to deal with the emotion on a conscious level. Based on this indescribable aspect of love as an emotion, it may be that emotions like this are too complex to rationally define at this point in time, either in a scientific or political forum. Yet the latter has already done so by restricting the rights of homosexuals, specifically in marriage law. As a result, future research is needed to help show that there while there may be differences in the ways that individuals experience love, the basics correlates of the emotion are universal. This research would help establish public policy that gives all people the same opportunities to experience love.






Dawkins, R (1976, 1989). The Selfish Gene. Oxford, Oxford University Press.

Pinker, S (1997). How the Mind Works. New York, W.W. Norton and Co.

Pinker, S (2008). Crazy Love. Time Magazine. New York, Time Inc. January 28, 2008.


Serendip Visitor's picture

why we love who we love

Life is a precarious thing - if a population's birth rate falls below two (and a bit) children per couple (as it has done in western cultures) it risks extinction. After 2 billion years of sexual reproduction, one would think that evolution would have solved the problem of successfully matching male and female (of course, evolution can't predict changes in climate, or the emergence of other external phenomena that may affect population survival).

When it comes to mate selection, the simplest rule: WHAT WORKED ONCE STANDS A BETTER THAN RANDOM CHANCE OF WORKING AGAIN seems obvious, even infallible. It implies that the closer the child can become like its same sex parent, and later choose as a mate the closest replica it can find of the opposite sex, the more likely the match will result in a successful birth. After all, this is the whole point of sexual reproduction - to pass on a package of life-promoting physical and behavioural traits. Yet observation says otherwise.

Can anyone suggest why this simple rule is not in operation? How could other mechanisms override this rule?

Serendip Visitor's picture

A rational irrational notion

It's pretty interesting that they refer to love as irrational and then attempt to provide a rational basis for its existence. There are countless examples of humans loving humans of no relation who contribute nothing to society and is a largely parasitic relationship. Love is giving when receiving is not deserved. Otherwise it is not love and is simply obligation. This defies the logic of evolutionary adaptations. It nurtures parasitism which deters progress.

Paul Grobstein's picture

is love adaptive?

"love is an evolutionary adaptive emotion because it allows us to maintain relationships with one another"? Seems to me one could equally make an argument that it leads to disruptions of relationships (as per Helen of Troy). Is that "adaptive"? Something we want to give "all people the same opportunities to experience"?
Serendip Visitor's picture

Love as evolution

If love is the foundation of survival for the purpose of reproducing, then shouldn't the emotion of this be lust rather than love? With this, doesn't love therefore become a irrational emotional that should be able to be controlled? However by what is stated above love is known as a unconscious defense mechanism of 'I scratch your back, you scratch mine ' To me it doesn't make sense, if it was due to evolution then love would not exist as a emotion however, could love be determined as a obsession? If you look at the brain waves of someone in love and someone suffering with O.C.D apparently there are similar results. Can anyone expand on this for me?