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What Is Love? An Evolutionary Perspective

Dr. Thomas Swan has a PhD in psychology from the University of Otago. His work explores theories of emotion, memory, and belief.

Love is often symbolized by a red rose.

Love is often symbolized by a red rose.

Love is at least as old as the written word, and as unsullied by the vicissitudes of time as the ancient clay tablets that first chronicled its poetic creations. Four thousand years ago, a young priestess wrote of her love for the king of Sumer: the first civilization to develop writing. The cuneiform clay tablet inscribed with the poem was unearthed a century ago in Iraq. It revealed a story of captivation and seduction that would be at home in any modern day erotic novel [1]. It seems that love is an unalterable and universal facet of the human condition, so how did it get there?

Why Do We Love?

The best way to illustrate the necessity of love is to imagine two couples living millions of years ago. The first couple is a loveless union. When the woman falls pregnant, the father abandons her to search for other mates. The second couple is in love, and when the woman becomes pregnant, the father remains by her side.

For the first couple, the mother will be at risk of attack from rivals or beasts during pregnancy, and the child’s upbringing will be dangerous without the protective presence of the father. In looking for other mates, the father will be risking injury and death by competing with other males for female affection.

For the second couple, the mother will be protected during pregnancy and the child will be protected during its upbringing. Once the child is born, the father will be able to have another child with the mother, giving him long-term access to a fertile mate.

The clay tablet holding the oldest love poem.

The clay tablet holding the oldest love poem.

In these scenarios the loving couple is more likely to live longer, and their children are more likely to survive to adulthood. This means their genetic material is more likely to be passed on to the next generation. Within this material will be the genetic anomalies that caused them to love each other.

Over time, the descendants of the loving couple will become far more numerous than the descendants of the loveless couple. Eventually all humans will possess the genetic anomaly that causes us to love. In other words, love is a naturally selected genetic trait that helps humans to survive [2].

  • Fessler and Haley (pdf)
    This academic paper includes a section on the evolutionary benefits of romantic love, as well other adaptive strategies of affect that enhance cooperation in social contexts.

What Is Romantic Love?

Love can be described as a recurrent mood, which is a long-term affective state that can be cognitively reflected upon (i.e., people can at least try to describe their feelings), and which is punctuated by bouts of spontaneous, passionate emotion.

In the case of love, the emotions are positive and include affection, empathy, intimacy, and loyalty. These emotions help to facilitate a committed attachment to the other person and, as described above, they function to hold interpersonal relationships together in a way that helps an individual pass on their genetic material.

Given the utility of romantic love, different forms of love have been found to apply to family, friends, pets, and more abstract ideas such as deities, political causes, and groups of people (e.g., sport teams), with each form lacking or having additional qualities when compared to romantic love.

Why Is Love Divine Or Poetic?

Given that emotions are typically involuntary, are not connected to reasoning capacities (i.e., they might appear illogical), and seemingly "come from nowhere," the passionate emotions that characterize love means that we are especially deficient in our ability to rationally reflect on the experience. This ambiguity means that love can be attributed to any number of other concepts, and particularly those are share some of its qualities.

For example, love is often claimed to be of divine origin because of its intangible nature and the benevolent "purity" of its perceived effect. Notions of purity, absoluteness, benevolence, intangibleness, and complexity are also attributed to gods, making it easy for some people to connect these concepts. For similar reasons, love is often described with poetry or metaphor.

The competition between males for the affection of females would also have served to exaggerate love (e.g., "my love is greater than yours") and skew its definition (e.g., "my love is unique and special"). Indeed, love may be difficult to define for precisely this reason. If one cannot describe their love for another in a formulaic way, then it appears special, increasing the chances of reciprocation. Love may have evolved to be confusing!

Romeo and Juliet: Love feels special and unique to each of us.

Romeo and Juliet: Love feels special and unique to each of us.

Love, The Emotion

Although love appears to be closer to a mood than an emotion, the various emotions that punctuate the mood (e.g., affection, empathy) might also be explored as a single independent "love" emotion with physiological markers.

For example, the British professor and television presenter, Robert Winston, has shown that an emotional state that he calls "love" involves the release of chemicals that stimulate the pleasure centres of the brain [3]. The release of these particular chemicals, which include dopamine and serotonin, support the idea that love is a positive emotion that reinforces attachment behaviour.

Love, however, should not be confused with lust, which is a negative emotion because it drives people to avoid a negative outcome (not having a romantic partner) by changing their behavior toward finding a partner [4]. This is why romantic love might follow lust (i.e., once you have a romantic partner, love positively reinforces this behavior), and why they are different affective states.

In summary, if love wasn’t indescribable we wouldn't see it as personal and unique, and its evolutionary function for holding families together would be degraded. Love is blind because sometimes it’s better not to see.


[1] Wolkstein, D. (1983). Inanna, Queen of Heaven and Earth: Her Stories and Hymns from Sumer. Harper Perennial.

[2] Fisher, H. (2006). Why We Love: The Nature and Chemistry of Romantic Love. Henry Holt and Co.

[3] Winston, R. (2005). Human. Dorling Kindersley Publishers Ltd.

[4] Parkinson, B., & Colman, A. M. (Eds.). (1995). Emotion and motivation. Longman Publishing Group.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2012 Thomas Swan


Thomas Swan (author) from New Zealand on June 16, 2012:

Hi d.william, I agree, love and lust are not morally wrong. In my similar article on the seven sins I talk about how these sins condemn a number of emotions (greed, lust, envy, etc) that would only be part of humanity if they served an evolutionary purpose. It's the knowledge that one can act on an emotion immorally that is sinful, not the emotion itself.

There are indeed many forms of love. It's a theory of mine that love for friends is something we project to increase reciprocal behaviour. It's ultimately selfish, but then I think everything is at the basest of levels. There's nothing wrong with selfishness giving rise to altruism or charity.

I think religions have been dictating our loves for thousands of years. My quarrel is with religions claiming love as God-given. They do the same with morality, a topic on which I'm planning to write about in future. We'll never understand these psychological states if we claim God made them.

d.william from Somewhere in the south on June 14, 2012:

Indeed, thoughtful and thought provoking. There is no rational explanation for why one falls in love with another person. There are many kinds of love, and depths of intensity that range from love of a child, to love of a pet, to uncontrollable lust, etc.. And none of them are morally wrong, except as differentiated by man's ignorance.

We have reached a new low in religious idiocy today when religions and politicians try to mandate who one falls in love with, and which love is better than the other.

Thomas Swan (author) from New Zealand on June 10, 2012:

Thanks Trahn, some of your hubs look interesting to me too.

TrahnTheMan from Asia, Oceania & between on June 09, 2012:

A very thoughtful, and thought provoking hub Thomas.