How Love Works

Part 1 of a series on love.
By Aditya Nair

Every thought, idea, or emotion that you’ve ever had is the result of networked interactions of cells in the brain called neurons. Every time you feel a strong emotion like the apprehension in the pit of your stomach before a biology test, the excitement of a sporting event, and the warmth and joy of being with a significant other can be traced back to a complicated cascade of chemical reactions.

One of these emotions, love, has become a central element of our individual and societal existence. So strong is love’s emotive power that a grossly disproportionate amount of music, art, and literature is devoted to themes of love or affection. One would be hard pressed to find a culture that doesn’t have a song, poem, or book enveloped within its artistic canon. But why is love such a central part of our personal and cultural identities? What exactly is the neuro-biological basis for love?

As with many biological explanations, the answer starts with evolution. At the face of it, love seems like a very silly emotion to evolve. In the struggle for survival, being irrationally attached to something only seems to weigh a creature down. Envision the case of an early hominid that might have escaped a sabre-tooth tiger attack, but instead returned to save his infant daughter and mate. Surely his chances of survival would have been higher had he escaped as quickly as possible instead of returning to his loved ones. If a creature subject to Darwinian evolution had a behavioral Achilles heel, love is surely it.

One way to begin to address this issue is to note that the commonly held conception of “survival of the fittest” requires a certain degree of nuance to be fully accurate. Evolution doesn’t actually select for the fittest animal, but rather for the fittest offspring of an animal. It doesn’t take much thought to demonstrate why this must be the case. A particular animal, for instance an alpha-male gorilla, may be by leaps and bounds the strongest of his fellow gorillas. In the case of natural calamity, starvation, or disease, he is most likely to survive due to his strength and vigor. However, if this individual happens to be infertile, his physical fitness would count for nothing in the eyes of natural selection. He would age much like any other animal and his death would result in him fading into irrelevance from an evolutionary standpoint. However, if he had more kids than his competitors, who in turn had more kids than their competitors, his genes would carry on through posterity and be embraced by natural selection. Of course, if there were a selective pressure that killed animals before they could reproduce, “survival of the fittest” would come into play. But given that a particular animal will reproduce, it’s not precisely “survival of the fittest” that is the concern of evolution. Rather, it’s the less pithy “survival of the genes of the individual most successful at having viable and fertile offspring”.

Over the years, organisms have developed different strategies for maximizing their number of healthy offspring. Trees, for example, produce a tremendous number of offspring (seeds) so that even if an almost negligibe proportion of them survive to produce offspring of their own, the tree’s genes will endure. These organisms invest a relatively small proportion of their valuable energy resources caring for their offspring and instead focus on producing as many offspring as possible. Their offspring tend to become functionally independent earlier on in life, so they are not vulnerable in the absence of child care.

On the other hand, some organisms choose the opposite path. Their strategy is to create only a relatively small number of offspring, but ensure that a larger proportion of them reach viable adulthood. These organisms invest a large proportion of their resources into caring for their offspring. Humans fall into this category. This method of reproduction could begin to explain some aspects of human love.

Humans have big brains. Big brains are the plus sized SUV’s of the evolutionary world: expensive, energy sapping, and difficult to maintain. Developing such a brain is difficult, and takes time. Rather than grow this massive brain in the womb (which would lead to a more difficult birthing process), humans undergo brain development outside of the womb to a greater extent than other organisms and primates. During this development period, humans are largely dependent on their mothers for safety and sustenance. Much of the mother’s time and resources go towards caring for her child for a relatively long period of time. If one is an adult male, developing a strong attachment to the mother may ensure lasting resources and the long-term safety of the child. Likewise, female attachment to the male may be explained by a desire to provide the child with resources that only the male can offer.
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Could it be that the fundamentally human emotion of love can be explained by this very practical quirk in evolution? We will continue to explore and analyze the neurobiological considerations in future installments.