The Molecule of More: How a Single Chemical in Your Brain Drives Love, Sex, and Creativity―and Will Determine the Fate of the Human Race

by Daniel Z. Lieberman

Yet sometimes when we get the things we want, it’s not as pleasant as we expect. Dopaminergic excitement (that is, the thrill of anticipation) doesn’t last forever, because eventually the future becomes the present. The thrilling mystery of the unknown becomes the boring familiarity of the everyday,

When things become part of the daily routine, there is no more reward prediction error, and dopamine is no longer triggered to give you those feelings of excitement.

Passion rises when we dream of a world of possibility, and fades when we are confronted by reality.

Dopamine has a very specific job: maximizing resources that will be available to us in the future; the pursuit of better things.

The novelty that triggers dopamine doesn’t go on forever. When it comes to love, the loss of passionate romance will always happen eventually, and then comes a choice. We can transition to a love that’s fed by a day-to-day appreciation of that other person in the here and now, or we can end the relationship and go in search of another roller coaster ride. Choosing the dopaminergic kick takes little effort, but it ends fast, like the pleasure of eating a Twinkie.

According to anthropologist Helen Fisher, early or “passionate” love lasts only twelve to eighteen months. After that, for a couple to remain attached to one another, they need to develop a different sort of love called companionate love. Companionate love is mediated by the H&Ns because it involves experiences that are happening right here, right now—you’re with the one you love, so enjoy it.

Most couples have sex less frequently as obsessive dopaminergic love evolves into companionate H&N love. This makes sense, since oxytocin and vasopressin suppress the release of testosterone. In a similar way, testosterone suppresses the release of oxytocin and vasopressin, which helps explain why men with naturally high quantities of testosterone in their blood are less likely to marry. Similarly, single men have more testosterone than married men. And if a man’s marriage becomes unstable, his vasopressin falls, and his testosterone goes up.

On average, women have the highest levels of testosterone on days thirteen and fourteen of their menstrual cycle. That’s when the egg is released from the ovary, and they are most likely to get pregnant. There are also random variations from day to day and even within a day. Some women produce more testosterone in the morning, others later in the day.