Today I’d like to talk about: The Yin and Yang of Desire — Dopamine, Prolactin and Testosterone.
Let’s talk about love, lust and desire. But instead of looking at these things as social phenomena, let’s look at the chemical reactions going on inside our bodies that make us feel and behave the way we do.
There are clear links between certain chemicals and our most basic drives, which explains, for example, why we feel horny one moment and utterly disinterested the next. Or why our sex drive peaks after exercise. At the core of our sexual and affectional interests and behaviors lie the two chemicals — dopamine and prolactin. In many ways they are complimentary to one another; dopamine turns on desire and prolactin turns it off.
Dopamine is a neurotransmitter. This is basically your body’s pleasure and reward system. Our brains releases dopamine, to one degree or another, when we see, read or think about something sexy, taste something sweet, puff a cigarette, or come into skin-to-skin contact with another person. When dopamine levels are high, our libido goes into overdrive. Sometimes levels can be so dramatic that a person will neglect other essential bodily functions like eating and sleeping. Some “street” drugs —meth and coke among them — can mimic the body into thinking it’s dealing with dopamine.
Dopamine is critical to the way the brain controls our movements. If there’s not enough dopamine, we can’t move, or control our movements. If there’s too much dopamine, we are plagued with repetitive moments like jerking, tapping and twitching.
Get this; novel situations can increase dopamine releases. For example, hooking up with someone for the first time triggers especially high levels of dopamine. Curiously enough, these same high levels will not occur again during subsequent hookups with that same person. This is called the one-night-stand phenomenon; it’s why you can be attracted to someone at first encounter but not afterward.
However, falling in love with someone can sustain high dopamine levels for a longer period of time. This explains why physical infatuation is at its peak in the beginning months of a relationship. Also dopamine floods the brain when we get drunk or take certain drugs, which is why drinking alcohol can make a potential partner look more attractive.
Prolactin is dopamine’s foil. It causes dopamine levels to plummet. Prolactin is a hormone, as opposed to a neurotransmitter, like dopamine. It floods the body during orgasm, virtually shutting down the sex drive, which is nature’s way of allowing us to attend to other essential bodily functions like eating and sleeping. Prolactin release in men will temporarily disable our ability to have an erection. This is called the refractory or recovery phase of our sexual response cycle. And prolactin is at least partially responsible for that happy, relaxed state after we cum. This is precisely the release women get while breastfeeding; in fact, the word “pro-lactin” directly indicates its role in milk production.
Prolactin primes the mind for long-term attachment — a role that helps the mother bond with her suckling child as well as lovers to each other. This means that if you stick around cuddling with your partner right after sex, you may actually start to like him/her more and more. This is called the pair-bonding effect. But prolactin’s dopamine-reducing action has a darker side. It cancels the tolerance you may have for your partner’s flaws.
While dopamine and prolactin are good indicators of the immediate workings of sexual pursuit, it is testosterone that best explains long-term changes in courtship. Testosterone is responsible for the masculinization of the adolescent male body during puberty. And it increases the dopamine levels that regulate our sex drive. But testosterone leaves its fingerprint on the body as much as the brain. It’s the catalyst for changes in skin tone, fat distribution, musculature and demeanor, which are signals to others that this individual male is sexually mature and in good health.
However, if you get a fever or become depressed, your testosterone levels can drop significantly. Malnutrition or high levels of anxiety or stress will also interfere with testosterone levels. The most immediate effect of this is a decrease in libido, and a noticeable drop-off in energy levels as well as confidence. There’s no doubt about it; testosterone levels will signal to potential mates that you are in the throws of depression, stress, anxiety or malnutrition. You will appear a little less attractive to people subconsciously. That’s why a confident, dominant male with high-testosterone levels generally enjoy more mating success.
Testosterone levels are highest in the morning, then wanes throughout the day. It’s also much higher in men in autumn and lowest in the spring.
However, sexual desire is still more complicated than is known to science, and there may be multiple archetypes of partners we’re drawn to — there is evidence that aggressive high-testosterone men appear sexier to women and gay men for a one-night stand. But softer, more sensitive balanced men are more likely to tug at our heartstrings in a relationship. Scientists reason that the bulkier mate is more likely to be physically powerful and carry good genes to create strong children. While the slimmer guy is a more loving, reliable partner likely to help raise the kids so they survive to adulthood. The effect of this strange contradiction seems to be a biological predisposition against monogamy and sexual exclusivity.
But none of this is carved in stone. A man’s hormone’s levels increase when he is in a competitive environment or carries out acts of aggression, which can explain how guys seem to bulk up quickly when they go to prison or join sports teams. These levels decrease when he feels intimidated or humiliated, which might explain why those who get picked on at school stay skinny and mild-mannered compared to their peers. This in turn made them easier targets and only increased the likelihood of them being bullied.
This is not uncommon behavior among primate colonies that have huge alpha males looming over a population of smaller, submissive males and females. While this is not a perfect parallel to human social groups, it does go a long way in explaining how a social environment can be a precursor to physical body changes. And just so you know, our testosterone levels also drop during long-term relationships, giving the male brain a sense of stability and mellowness, easing off the drive to forage for new sexual partners.
Science alone lacks a moral element, and fails to explain, in a modern context, why we should desire to be masculine, aggressive, potent or dominant in the first place. In nature, the alpha-male is the most likely to enjoy reproductive success, but that isn’t what gives our lives value today. We might have more success being an average male that falls in love and becomes a good provider. And in the modern world it’s probably the more stable and sensitive man who is most likely to sire children.
Still, science gives important clues to what’s going on in our minds and bodies and that of our potential partners. A lot of our basic inclinations are out of our control, but when we know what causes them or what to expect, we can work with them for the best outcome.