Orgasm lasts for a few seconds (normally not over ten); continued stimulation can produce additional orgasms in females. In brief, after one orgasm a male becomes unresponsive to sexual stimulation and cannot begin to build up another excitement phase until some period of time has elapsed, but females are physically capable of repeated orgasms without the intervening "rest period" required by males.

Female Orgasm: Why?

Female orgasm has remained a mystery compared with the more frequent and easily achieved male orgasm. In terms of evolution and adaptation, women do not need to experience orgasm in order to reproduce. So what is the function of orgasm in females?

Darwinian theorists who made early attempts to address female orgasm proposed that orgasm keeps a woman lying down after sex, passively retaining sperm and increasing her probability of conception. Others suggested that it evolved to create a stronger pair bond between lovers, inspiring in women feelings of intimacy and trust toward mates. Some reasoned that orgasm communicates a woman's sexual satisfaction and devotion to a lover.

Evolutionary psychologists have been exploring the proposition that female orgasm is a sophisticated adaptation that allows women to manipulate--even without their own awareness--which of their lovers will be allowed to fertilize their eggs (3).

It's no secret that some women have multiple orgasms--Masters and Johnson documented the phenomenon more than 20 years ago (6).

The female orgasm presents a paradox. While it is much more difficult to achieve than male orgasm, when achieved, it seems capable of repeated pleasure: the so-called multiple orgasm. Why, in any adaptational argument, should this be? Why should the female's pleasure not be as direct and as immediately rewarding as the male's?

Theories suggest that muscular contractions associated with orgasms pull sperm from the vagina to the cervix, where it's in better position to reach the egg. Reseachers discovered that when a woman climaxes until 45 minutes after her lover ejaculates, she retains significantly more sperm than she does after nonorgasmic sex (3).

Pills for Orgasm in Women

Researchers at University in New Brunswick, NJ, believe they have isolated a chemical that produces orgasms in women.

Through experiments with lab rats, the researchers determined that the brain can receive signals of sexual response through a pathway other than the spinal cord. They found an alternate pathway through the vagus nerve, which goes directly from the cervix, through the abdomen and chest cavity, into the neck and to the brain stem.

Women who were paralyzed and had no feeling below the breast area were, in fact, capable of having orgasm ((7)).

Those experiments helped lead to the isolation of the vasoactive intestinal peptide, which he believes is the neurotransmitter, or nervous system chemical messenger, in the body that causes the orgasm sensation in the brain.

That same chemical may also have strong pain-suppressing qualities rivaling morphine that one day may make it a natural source of pain relief (7).

The finding could lead to a pill that would give a person the same sensation as an orgasm and might be used in treating pain.

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Author: Dr. Silvia Helena Cardoso, PhD. Psychobiologist, master and doctor in Sciences by the University of São Paulo and post doctoral fellowship by the University of California, Los Angeles. Invited Professor and Associate Researcher of the Center for Biomedical Informatics, State University of Campinas (Unicamp), Brazil.