What Do Women Want

unmistakably what she craved. This went on and on and on.
    As we watched, Pfaus mentioned the anatomical oversights that had squelched our understanding of the clitoris—rat and human—until a decade before. The organ has sizeable extensions, lying internally in the shape of bulbs and wings. These are positioned, in part, just behind the front wall of the vagina. Yet these nerve-rich formations had gone mostly unnoted by modern anatomists, who either left them undrawn or gave them no import. Science seemed almost to have willfully diminished the organ, cutting it metaphorically away. It was another lesson in the minimizing of women’s desire. Then, beginning in the late nineties, Helen O’Connell, an Australian urologist, detailed the organ’s sprawl, its many inches in reach. And she championed its sensitivity to pressure through the vaginal sheath—sensitivity perhaps responsible for vaginal climaxes and possibly the explanation for the fabled and debated G-spot. O’Connell was blunt about the averted eyes of her scientific predecessors. “It boils down,” she said, “to the idea that one sex is sexual and the other is reproductive.”
    Now Pfaus pulled apart his plastic model of a human brain, his fingers in the folds. He spoke about the neurotransmitters that define eros for women as well as men. The libido is, in a sense, two-tiered. There’s the lower realm, in which hormones rise up from the ovaries and adrenal glands, float along the bloodstream to the brain, and fuel the production of the brain’s neurotransmitters. How exactly this fueling happens is still a mystery; so is the quantity of fuel needed to keep the production line running well. The higher realm is the brain itself, the domain of the neurotransmitters. These biochemicals, not the lowly hormones, form the essence of lust.
    Dopamine—its atoms arranged like an antennaed head with a spikey tail—is, in a way, the molecular embodiment of desire, its main chemical carrier. It isn’t only that; it speeds through a multitude of the brain’s subregions and exists in infinite relationships with other neurotransmitters and has all sorts of effects, from motor control (the trembling and sluggishness of Parkinson’s patients stem from a shortage of dopamine) to memory. But dopamine is the substance of lust. And by way of his mini deli slicer, Pfaus had narrowed his sights on two tiny territories at the brain’s primal core, the medial preoptic area and the ventral tegmental area. These were the heart of dopamine’s sexual system, he said, “the ground zero of desire.”
    From this primitive epicenter, dopamine radiates outward. “A dopamine rush is a lust-pleasure,” Pfaus continued. “It’s a heightening of everything. It’s smelling a lover up close—a woman inhaling that T-shirt. It’s starting to screw; it’s wanting to have; it’s wanting more.”
    Yet for the excitement of dopamine to fix on an object, for it to be felt as desire rather than as a splintering into attentional chaos, it has to work in balance with other neurotransmitters. Serotonin plays an indispensable part. Unlike dopamine’s keen drive, he said, serotonin dampens. Unlike dopamine’s lust, serotonin instills satiation. Flood female rats with antidepressants—like the selective serotonin reuptake inhibitors, the SSRIs—that bolster serotonin, and the females will spend less time courting males. They will also bend their spines less fully, raising their butts less completely, to accommodate the males they do mate with.
    It was important, Pfaus emphasized, to understand serotonin’s virtues. They go beyond keeping depression at bay. The neurotransmitter also allows the brain’s frontal lobe, more precisely the prefrontal cortex, the region of planning and self-control, to communicate effectively within the organ, to exert what’s known as executive function. Serotonin reduces urgent need and impulse; it facilitates sensible thoughts and orderly actions. The problem, though, is that if serotonin is too strong in relation to dopamine, a woman making love is likely to find herself thinking about the next day’s schedule rather than feeling overtaken by sensation and craving. But with serotonin and dopamine in the right balance, erotic energy will be neither displaced by tomorrow’s to-do list nor permitted to fracture into chaos. With the frontal lobe and the libidinous core in harmony, desire can have both form and force.
    For all the agility of his