Interesting piece in the Times today about sex drive in relationships, even though it’s geared toward women:

A drop in partnered sex among cohabitating or married partners is a fact of life – advice on how to maintain or rekindle desire has been around since the beginning of written history. Almost universally, humans seem to struggle against the notion that sex is just for reproduction.

Professor Laumann’s study indicates that by age 30, three-quarters of Americans are either married or living with someone, but they are starting to have “partnered sex” less often than people in their 20’s. In their 30’s, more people are having sex with a partner a few times a month, and fewer are having sex a few times a week. By their 40’s, this disparity more than doubles for both men and women.

… Helen Fisher, an anthropologist and the author of, most recently, “Why We Love,” has long studied the human brain and love. She theorizes that the brain has evolved three mating drives: lust, the craving for sexual gratification; romantic love, a focused attention on another, often compared to an opiate-like state; and attachment, the feelings of calm, security and union with a long-term partner. Each drive travels along a different pathway in the brain, Dr. Fisher and colleagues say, each associated with different neurochemicals.

“Lust is associated primarily with testosterone in both men and women,” she said. “Romantic love is linked with the natural stimulant dopamine and perhaps norepinephrine and serotonin. And feelings of attachment are produced primarily by the hormones oxytocin and vasopressin, which at elevated levels can actually suppress the circuits for lust.” …

Dr. Nachtigall of New York University makes a further point: “We’re the only mammal that outlives its reproductive functions. Technology helps us live longer and longer. We aren’t supposed to go into menopause; we were only supposed to live about 50 years.”