Galen of Pergamum, the great physician and medical researcher of antiquity, was one of many learned men of his time who believed that women had to have an orgasm during sexual intercourse for conception to occur. For 1,500 years this was the scientific consensus. How could we have continued to believe in the necessity of female orgasm when there must have been all kinds of evidence to the contrary? No one is sure, according to Daniel Bergner. When it comes to the study of female sexuality, scientists have tended to see what they expect, or want, to see, and there are fewer established facts than you would think. “Despite all the powers of contemporary science,” Bergner writes, “the seemingly straightforward anatomical question, is there a G spot? remains unanswered.”

So what are scientists seeing now? Bergner’s previous book, “The Other Side of Desire,” is a thoughtful study of unusual sexual inclinations — fetishism, sadism, attraction to children or amputees. In his new book, “What Do Women Want?,” which appears to have grown out of his earlier research, Bergner turns to what you might say is the largest group of sexual deviants: women, whose strange sexual parts and desires never seem quite as mainstream as men’s. Squeezed into these 200 pages are interviews with psychologists, psychiatrists and primatologists who have been “puzzling out the ways of eros in women”; a capsule history of ideas about female sexuality from biblical times to the present; the story of the so-far elusive hunt for a Viagra-type aphrodisiac for women; a discussion of the different types of female orgasm; and the personal accounts of a dozen or so ordinary women who talk about their sex lives and fantasies. The experiments and data Bergner writes about vary widely and don’t all point in the same direction, but he sets this tour of contemporary sex research against one particular shibboleth: the notion that women are naturally less libidinous than men, “hard-wired” to want babies and emotional connection but not necessarily sex itself. Bergner, a contributing writer for The New York Times Magazine, blames evolutionary psychologists for spreading a contemporary version of this old idea. He assembles a group of scientists from different fields who talk about how earlier sexist bias has obscured the existence, strength and significance of female sex drive in animal reproduction.

Here is one example, with monkeys: In the 1970s, a psychologist and neuro­endocrinologist named Kim Wallen noticed that the sexual behavior of rhesus monkeys was affected by the size of their cages. In close quarters the monkeys went at it like mad, and the male seemed to initiate sexual activity, which in turn seemed to confirm the prevailing idea that female monkeys were entirely sexually passive. But in larger cages, as in the wild, the females were the ones who chose their partners and initiated sex by following the males around and touching them demonstratively. The small cages, with their forced proximity, reduced monkey sex life to intercourse, obviating all the mating rituals in which female lust was the essential factor that set sex in motion. After Wallen’s observations, primatologists started seeing evidence that many kinds of female primates initiated sex, while their male counterparts pretty much sat around waiting for the ladies to take an interest in their erections.