Lust and Love: Who We Desire and Why We Stray

How the Love Doctor Finally Met Her Match

            I first met Helen Fisher at a conference where we were both speaking about sex, love, and relationships. My book Looking for Love in All the Wrong Places: Overcoming Romantic and Sexual Addictions had just been published and her book, Anatomy of Love: A Natural History of Mating, Marriage, and Why We Stray was just coming out. By background is in evolutionary psychology. She is one of America’s most prominent anthropologists and the author of six internationally best-selling books on the science of romantic love, attachment, adultery, divorce, and the evolution and future of human family life.

            She is from New York and was coming to California where I live to offer a workshop at the Esalen Institute in Big Sur. I had taught workshops there and she invited me to join her. I had read her earlier book, The Sex Contract: The Evolution of Human Behavior and I told her it had helped me better understand my marriage. She surprised me when she said, “I don’t think I’ll ever get married.” A surprising statement indeed from Chief Science Advisor to the Internet dating site

            I’ve continued to follow her work over the years and was pleased to learn that she recently fell in love and married science writer John Tierney. Though they had known each other for more than twenty years, they both had been in other relationships until they were both free at the same time and the sparks flew. It’s a wonderful love story for a woman who had been studying the anatomy of love for more than forty years and was now putting all the pieces together.  

The Evolution of Love and the Three Challenges All Creatures Must Face

            Whether you are a chimpanzee, a horse, or a human being, there are three things you must do: First, you have to seek a potential mating partner. Second, you must find one who is willing to mate with you. Third, you must ensure that the offspring live long enough to repeat the process. Do those three things and your species survives and thrives. Failing any one and your species dwindles and dies.

            All humans today evolved from ancestors who never broke the chain of success. Each of us had parents who had at least one child. Our parent’s parents had at least one child, all the way back through time.

            More than anyone I know, Helen Fisher has studied the intricacies of dating and mating, explains the process, and is living it. She not only draws on her experience and expertise as an evolutionary anthropologist, but also has teamed up with neuroscientists who are able to examine the biochemistry and brain systems that are involved with the various stages of love.

            Here is a great summary from Harvard University written by Katherine Wu with figures by Tito Adhikary. According to a team of scientists led by Dr. Helen Fisher at Rutgers, romantic love can be broken down into three basic categories: lust, attraction, and attachment. Each category is characterized by its own set of hormones stemming from the brain (Table 1).

Table 1: Love can be distilled into three categories: lust, attraction, and attachment. Though there are overlaps and subtleties to each, each type is characterized by its own set of hormones. Testosterone and estrogen drive lust; dopamine, norepinephrine, and serotonin create attraction; and oxytocin and vasopressin mediate attachment.

Each of these three categories correspond to the evolutionary necessities that must be met for our species to survive. Lust gets us interested in sex. Attraction focuses our attention on one specific person. Attachment keeps us together long enough to nurture and raise children so they can repeat the cycle. Of course, not everyone has children, but enough do so that our species survives and thrives. (Before the recent arrival of various forms of effective birth control, everyone who had sex was likely to produce children).


All creatures need to be motivated to action. Lust gives us the energy to get going.

“The sex drive evolved to motivate individuals to seek sexual union with any appropriate partner,”

says Dr. Fisher.

            The hypothalamus of the brain plays a big role in this, stimulating the production of the sex hormones testosterone and estrogen from the testes and ovaries (See Figure 1 below). While these chemicals are often stereotyped as being “male” and “female,” respectively, both play a role in men and women. As it turns out, testosterone increases libido in just about everyone. The effects are less pronounced with estrogen, but some women report being more sexually motivated around the time they ovulate, when estrogen levels are highest.

Figure 1: A: The testes and ovaries secrete the sex hormones testosterone and estrogen, driving sexual desire. B and C: Dopamine, oxytocin, and vasopressin are all made in the hypothalamus, a region of the brain that controls many vital functions as well as emotion. D: Several of the regions of the brain that affect love. Lust and attraction shut off the prefrontal cortex of the brain, which includes rational behavior.


            Meanwhile, attraction seems to be a distinct, though closely related, phenomenon, Dr. Fisher has found. While we can certainly lust for someone we are attracted to, and vice versa, one can happen without the other. Attraction involves the brain pathways that control “reward” behavior (Figure 1), which partly explains why the first few weeks or months of a relationship can be so exhilarating and even all-consuming.

            Dopamine, produced by the hypothalamus, is a key player in the brain’s reward pathway – it’s released when we do things that feel good to us. Dopamine can get us what we want or it can cause great pain and suffering. I’ll have more to say about dopamine in future articles. In their book, The Molecule of More, Daniel Z. Lieberman, MD and Michael E. Long say,

“Dopamine motivates you to pursue, to control, and to possess the world beyond your immediate grasp…It is the fuel for the motor of our dreams; it is the source of our despair when we fail. It is why we seek and succeed; it is why we discover and prosper. It is also why we are never happy for very long.


            Attachment is all about connection. From an evolutionary point of view, it’s the glue that holds a couple together long enough to deal with the stresses of childbirth and raising children until they can survive and thrive on their own.

            “Termed ‘companionate love’ in humans,” says Dr. Fisher. “Attachment is characterized in birds and mammals by behavior that may include defense of a mutual territory, mutual nest building, mutual feeding and grooming, separation anxiety, and shared parental chores. In humans, attachment is also characterized by feelings of calm, security, social comfort, and emotional union.”

            While lust and attraction are pretty much exclusive to romantic entanglements, attachment mediates friendships, parent-infant bonding, social cordiality, and many other intimacies as well. The two primary hormones here appear to be oxytocin and vasopressin (Figure 1 above).

            This simplified model helps us understand a good deal about love, but we also know it can become complicated very quickly and the complications can be exciting and painful.

“For each system, the neural circuits can be expected to vary among individuals within a species, and over the life of an individual,”

says Dr. Fisher.

“Men and women can express deep attachment for a long-term spouse or mate at the same time they express attraction for someone else, and also while they feel the sex drive in reaction to situations unrelated to either partner. We are physiologically capable of ‘loving’ more than one person at a time.”

            I followed the pattern of many men and women. I married young, had children, got divorced and tried again. I describe a bit of my own journey in my chapter, “Confessions of a Twice-Divorced Marriage Counselor,” in my book, The Enlightened Marriage: The 5 Transformational Stages of Relationships and Why the Best is Still to Come. My third wife, Carlin, and I have been married now for 42 years.

            Helen Fisher took a different path, studying the art of love, but waiting until she was 75 to marry for the first time. Love is strange and wonderful and we all have a lot to learn. I look forward to your comments and questions. Let me know if this article was helpful.

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