Love Drugs
The Chemical Future of Relationships
Brian D. Earp and Julian Savulescu




AMONG THE YUSUFZAI PUKHTUN, a tribe in northern Pakistan, it is rumored that the most powerful love potion you can get is water that’s been used to wash the body of a dead leatherworker. In Swedish folklore, to capture your crush’s attention, you should carry an apple in your armpit for a day—and then present it, bathed in your own special scent, at an opportune romantic moment. Since Roman times, at least, a long list of weird tinctures and funny foodstuffs have been thought to stimulate lust, love, and good relationships. Sometimes love doesn’t just happen. Sometimes you have to help it along.

Anti-love remedies have a fabled past as well. According to one ancient tradition, a little bit of bloodletting would cool your passions. So would drinking plenty of water, getting lots of exercise, and avoiding rich food and wine. The Roman poet Ovid, in his Remedia amoris (The cure for love), recommends taking on multiple lovers to redirect your erotic desires, distracting yourself with friends or fighting in a war (if you can find one), and avoiding sappy poetry. He also warned against turning to “harmful herbs” and the “magic arts.” Such potions, he counseled, were a sham.

And they were a sham—or wishful thinking, to put it less harshly. But today, such fantastical visions are becoming technological reality. Thanks to recent advances, not in witchcraft or wizardry but in neuroscience and related fields, the biological underpinnings of romantic love are being revealed. Some scientists think that the more we understand this biology, the more we will be able to influence or even manipulate those factors directly, through biochemical intervention. In other words, the prospect of real-life love drugs (and anti-love drugs) is now upon us.

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It is difficult to talk about love—romantic love, anyway, which is the kind we have in mind for this book—without immediately stumbling into clichés. Love is discussed so much that it can seem as though there is nothing new to say about it. Even when it is groan-inducing, being neck-deep in love can be one of the best experiences of life, and being bereft of love can be one of the worst. This is why love, the hope of love, or the loss of love tends to inspire dramatic movie plots, emotional songwriting, and poetry (even by those who would never be caught dead scribbling rhyming couplets otherwise).

Love also has its share of downsides. Friendships are often thrown under the bus in the race for romance. When we’re in love, we want to stay in love, and this can sometimes feel like a high-stakes battle for survival. It can make us overly protective, jealous, and anxious. When we lose love, this tends to be among our most profound losses, and we may obsess about what we could have done differently. Unrequited love can be torture. And missed opportunities for romance that are only fully recognized later may fuel deep regret.

The two of us have thought a lot about love. We’ve each been in love (more than once; not with each other). We’ve experienced heartbreak. We’ve written our share of bad poetry. But as philosophers and bioethicists, we have also tried to get a grasp on different ways of understanding what love is—and on the practical and ethical significance of intervening, literally, in the “chemistry” between romantic partners.

Love and other drugs

Enter love drugs, two words that don’t normally go together, and each one meaning something different to different people. Before diving into the science and ethics of love-enhancing biotechnology, then, we need to say what we mean by these terms.

We’ll start with “drugs” because the concept is more straightforward. Drugs are just chemicals. That is essentially the entire definition. In practice drugs are usually thought of as specific chemicals that can be relatively easily taken into the body, whether by swallowing, snorting, inhaling, or absorbing them through the skin, which have some kind of physiological or psychological effect.

The kind of effect usually matters for how we regard these chemicals, though how this matters is not straightforward. When the intended effect is to cure or reduce the symptoms of a disease, drugs are usually called medicine. When the intended effect is recreation, spiritual development, or the exploration of alternative states of consciousness, drugs are usually not called medicine and just keep the generic label “drugs.” In fact, one and the same chemical substance might be considered “medicine” in one context, if used in a particular way or toward a particular end, and just a regular old “drug” in another context, if used in a different way or toward a different end. Even within the category of medicine, a single drug might produce the intended effect or a side effect depending on why it was prescribed. A popular textbook on pharmacology makes the point like this:

Amphetamine-like drugs produce alertness and insomnia, increased heart rate, and decreased appetite. Drugs in this class reduce the occurrence of spontaneous sleep episodes characteristic of the disorder called narcolepsy, but they produce anorexia (loss of appetite) as the primary side effect. In contrast, the same drug may be used as a prescription diet control in weight-reduction programs. In such cases, insomnia and hyperactivity are frequently disturbing side effects. Thus therapeutic and side effects can change, depending on the desired outcome.

We will say more about drugs later on, focusing on this issue of classification. As we will see, the decision to call a chemical substance a “drug” or “medicine” has important social and ethical implications. But before we get into that issue, we have a much more difficult task before us, which is to clarify what we mean by “love.”

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In the previous chapter, we explained that we will often use the word “love” informally, especially when quoting people or referring to their experiences as they understand them. In those situations, what we mean by love is whatever makes sense in the context, and this will usually be pretty clear. In other situations, we will bring up core features of love that tend to appear in a range of formal definitions, usually to give an account of how love in that sense could be affected by a chemical agent. But we don’t come down in favor of a single definition to use throughout the book. Mainly, this is because we don’t want our analysis of particular cases to depend on which theory of love you happen to agree with.

That being said, we do think that any plausible theory of love would recognize that it has, at minimum, a dual nature: two fundamental aspects that go together to make love what it is, neither of which can be ignored. In this respect we agree with the philosopher Carrie Jenkins, who has recently defended a “dual nature” account in her excellent book What Love Is. As Jenkins argues, the concept we are after cannot simply pick out a biological phenomenon, as in theories that reduce love to some kind of animalistic drive; but nor can it simply refer to a social or psychological construct or something that exists in a disembodied soul. Although you may have heard that romantic love was invented in the West in the last few hundred years, it wasn’t. It has been around (in one manifestation or another) since the dawn of our species, ingrained in our very nature. But the particular forms it has taken—as a result of the diverse ways people have understood it, reacted to it, molded it, and tried to control it or set it free—have indeed been different in different places and throughout different periods of history.

The idea is simple. Love would not exist as we know it if we did not have certain built-in biological drives related to attachment and mating. Moreover, the underlying function and makeup of our biology puts certain constraints on how we experience and even think about love at a higher level. At the same time, beliefs, norms, and expectations about love vary from culture to culture and may change over time; these higher-level factors can also affect our experiences and conceptions of love. They can even alter certain aspects of our neurochemistry. (If you don’t see how something like beliefs could affect neurochemistry, just imagine you are Oedipus Rex and you’ve recently learned that your lover Jocasta is your mother. You can bet this belief will put a damper on your sex drive.)

In contemporary Western society, three main clusters of beliefs about love tend to show up on the psychosocial side. These are the concepts and representations of love that appear in art, literature, pop culture, and everyday discussions. In no special order, we have (1) the idea that lovers should be a “good match” or “made for each other” (as in the notion of soul mates); (2) the idea that lovers should value each other for who they are in particular, for what makes them distinctive and irreplaceable; and (3) the idea that lovers should have a steadfast commitment to each other—usually a sexually monogamous one. We will weave in and out of this psychosocial dimension as we go along. First, though, we’ll give a quick overview of the biological dimension of romantic love.

In rough outline, the science goes like this. Underlying love is a set of overlapping but functionally distinct brain systems that evolved to suit the reproductive needs of our ancestors. These have been described differently by different theorists, but the most prominent account breaks things down into three systems: the lust system, the attraction system, and the attachment system. The role of lust or libido—as assigned by natural selection—is to inspire interest in a range of potential mating partners. The attraction system then narrows our focus down to a smaller number of partners, often one in particular. And the attachment system supports the formation of a long-term pair bond, which would have been important for successful childrearing in our ancestral environment.

Different brain chemicals, including testosterone, oxytocin, and dopamine, regulate these partially independent systems; the actions and reactions of these chemicals are largely responsible for our interpersonal drives and emotions. According to some theorists, these chemicals and the neural pathways along which they travel form the universal building blocks of romantic love. These building blocks are then reflected in, as well as shaped by, the sociocultural factors that bear on love across time and geography.

So, although there is wide variation in both subjective experiences and conceptions of love from person to person, between cultures, and over time, the thought is that—biologically speaking—the same basic “machinery” is under the hood. And by tinkering with this machinery through the application of certain biotechnologies, we are suggesting that it should be possible to influence those aspects of love that manifest “above the hood.”

Car analogies should be used sparingly. But let’s ride with this one a little longer. Obviously, the way a car runs, including how and where it moves through space, is not just a matter of internal mechanical aspects (corresponding to brains and biology in this analogy), like the rate at which pistons fire or how fuel is moved through the engine. It’s also shaped by external factors, like the beliefs and decisions of the driver (individual psychology), as well as the presence or absence of pedestrians, the commands of traffic signals, and arbitrary, which-side-of-the-road conventions (sociocultural norms and physical environment). In the same way, the course and character of love is not just a matter of neurochemicals, genes, and so on. Instead, what love is in a given context is constrained and informed by a complex set of outside forces that derive from history and society and interact with individual minds and behavior.

These forces range from prevailing cultural norms and assumptions about love—the stuff of books, films, poems, pop songs, and TV shows—to the explicit categories and language people use to describe love, to how people make sense of their experiences of love in terms of those categories and norms. These outside forces, too, are subject to change.

Tinkering with biology, then, is not the only way to modify love: its psychosocial aspects can be tinkered with as well. At a societal level, people might try to challenge existing narratives about love, including dominant norms for how love should manifest in different relationships. Should love require sex and passion, for example, to count as truly romantic? Or is romantic love more about loyalty and working through difficult problems? Different societies, or the same society over time, might emphasize different factors.

As these norms and narratives change, so too will the psychosocial side of love, including what counts as love in a given social context. At a more personal level, too, it may be possible to change how one experiences and even conceives of love by adopting different attitudes, changing one’s behavior or circumstances, or committing to an alternative lifestyle with its own set of values for conducting intimate relationships. (We will look at some examples of these kinds of changes in the pages to come.)

The important point for now is that social, psychological, and wider historical factors cannot be discounted. As the American psychologist and feminist Lisa Diamond argues: “Calling attention to the biological substrates of love and desire [does not] imply that biological factors are more important than cultural factors in shaping these experiences. On the contrary, research across many disciplines has shown that human experiences of sexual arousal and romantic love are always mediated by social, cultural, and interpersonal contexts, and ignoring these contexts produces a distorted account of human experience.”

At the same time, she continues, ignoring the biological underpinnings of human psychology and romantic behavior produces an equally distorted account: “human sexual and affectional experiences are neither ‘mainly cultural’ nor ‘mainly biological’ but must always be understood as products of powerful interactions between biological and social factors.”

In short, love has a dual nature. It is both biological and psychosocial, and it can be modified along either dimension.