What is Love?


Recently, a fellow bio-anth friend quizzed me about my definition of love. It’s that ever-present force, both bonding together and wreaking havoc on the lives of us mere humans. Love can be the death of us, yet it’s something we can’t live without.

Ironically, I shall start by stripping love of its emotional value. According to Hamilton’s rule (1964), an action benefits an individual when its reproductive benefit (multiplied by the degree of relatedness) is greater than the reproductive cost to the actor. Take, for example, self-sacrifice as a proxy for love. When asked if he would sacrifice himself to save his drowning brother, JBS Haldane famously quipped, “No, but I would to save two brothers or eight cousins.” Given the degrees of relatedness, this approach mathematically measures familial love. Is it harsh and desensitised? Quite. Nonetheless, it provides a useful starting point when considering the origins of this potent emotion.

While love might be adaptive between family members, it far from kin-exclusive. (On this note, I’ve always found it strange how the English language hasn’t more words for love. We don’t distinguish love for chocolate from love for one’s cat – or, indeed, love for one’s girlfriend from love for one’s sister!) One might argue romantic love is pair-bonding glue, cementing lovers together to produce offspring. Once again, this feeds into the idea of a biological tool ensuring reproductive success. It implies a sub-conscious, ‘selfish’ mechanism by which one maximises the prevalence of their genes. Those who love each other (and their dependants) are more likely to raise surviving children carrying their same genes.

However, this concept can be easily misconstrued. Some interpret that, if love is just an evolutionary adaptation, it can’t truly be love. This is fallacious. The evolution of opposability (to grasp objects) does not render the thumb any less real. Likewise, the evolution of love to increase fitness does not invalidate it. If human emotions have – even partly – arisen as a consequence of adaptation, they are still felt. No matter its evolutionary origins, love is as real as any sentiment.

Naturally, this begs the question: what does love feel like? I’ve no doubt it is different for everyone. After all, emotions are intrinsically subjective. Some people test love against its favourable effects – think butterflies, warmth, frequency of thought, or the strength of feeling. I find these overly symptomatic and subject to confirmation bias. It is simply too easy to falsely identify love based on feelings of affection and positivity. Fairweather love, I call it.

Instead, consider how adversity might change your perspective. If someone were troubled, how much would it affect you? Would it plague the back of your mind and keep you up at night? Would you feel completely right within yourself if this other person were not? I’m partial to the definition that, when you love someone, you cannot be fully happy in yourself if they aren’t. This covers all bases of relational love, from familial to romantic.

Some have critiqued this view because it implies dependency. However, I do not deny people are the agents of their own fulfilment and joy. I posit that your fundamental contentedness is bound to those you love. You may be happy as can be in your own endeavours, but if those you love are suffering, you share their pain. It is not a matter of being dependent on someone; it is a matter of empathy.

Of course, I could never claim to be any sort of expert. I’m comfortable with my naivety and I recognise my perception of love may be idiosyncratic. We might attempt to explain it mathematically, quantifying its value. We might attempt to diagnose it, identifying its effects and consequences. Be that as it may, love differs between individuals and even changes throughout one’s life. Love is an enduring enigma.



Hamilton, W., 1964. The genetical evolution of social behaviour. II. Journal of Theoretical Biology, 7(1): 17-52. DOI: 10.1016/0022-5193(64)90039-6
McElreath, R., and Boyd, R., 2007. Mathematical models of social evolution: A guide for the perplexed. Chicago (IL): University of Chicago Press




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