Well yes in most cases it is, besides it reproductive goals and recreational fun value.

Improved sense of smell: After sex, production of the hormone prolactin surges. This in turn causes stem cells in the brain to develop new neurons in the brain’s olfactory bulb, its smell centre.

Reduced risk of heart disease: In a 2001 follow-on to the Queens University study mentioned above, researchers focused on cardiovascular health. By having sex three or more times a week, men reduced their risk of heart attack or stroke by half.

Weight loss, overall fitness: Sex, if nothing else, is exercise. A vigorous bout burns some 200 calories–about the same as running 15 minutes on a treadmill or playing a spirited game of squash. The pulse rate, in a person aroused, rises from about 70 beats per minute to 150, the same as that of an athlete putting forth maximum effort. Muscular contractions during intercourse work the pelvis, thighs, buttocks, arms, neck and thorax. Sex also boosts production of testosterone, which leads to stronger bones and muscles.

Reduced depression: Sexually active women whose male partners did not use condoms were less subject to depression than those whose partners did. One theory of causality: Prostoglandin, a hormone found only in semen, may be absorbed in the female genital tract, thus modulating female hormones.

Pain-relief: Immediately before orgasm, levels of the hormone oxytocin surge to five times their normal level. This in turn releases endorphins, which alleviate the pain of everything from headache to arthritis to even migraine. In women, sex also prompts production of estrogen, which can reduce the pain of PMS.

Less-frequent colds and flu: Wilkes University in Pennsylvania says individuals who have sex once or twice a week show 30% higher levels of an antibody called immunoglobulin A, which is known to boost the immune system.

Better teeth: Seminal plasma contains zinc, calcium and other minerals shown to retard tooth decay. Generally this happens in women who regularly perform fellatio.

A happier prostate? Some urologists believe they see a relationship between infrequency of ejaculation and cancer of the prostate. The causal argument goes like this: To produce seminal fluid, the prostate and the seminal vesicles take such substances from the blood as zinc, citric acid and potassium, then concentrate them up to 600 times. Any carcinogens present in the blood likewise would be concentrated. Rather than have concentrated carcinogens hanging around causing trouble, it’s better to evict them. Regular old sex could do the job. But if the flushing of the prostate were your only objective, masturbation might be a better way to go, especially for the non-monogamous male. Having sex with multiple partners can, all by itself, raise a man’s risk of cancer by up to 40%. That’s because he runs an increased risk of contracting sexual infections. So, if you want the all the purported benefits of flushing with none of the attendant risk, go digital.