Hearing about all the troubles the Catholic Church has with celibacy has made me think a lot about my time as a Buddhist monk.

Shortly after I'd left robes the abbot came to visit me in my modest bungalow in Colombo. He patiently explained that there was little of any lasting importance in the secular world. Holding up his finger he said, "This is all sex is." Then he put the finger in his cup and stirred his tea.

At the time I half believed him, but the other half was solid American Dionysian, convinced there was no point to living without the frequent expression of holy union through erotic love.

While a monk, lying in my cot after a day of begging, meditation and study, I had vivid fantasies about my girlfriend off in Japan, and even the idea of suburban domesticity became attractive.

Now, a married middle-aged man with half the libido of my 20-year-old self, I can return to the question with a little more dispassion: As we begin to transcend the body and its clamouring demands and limitations, what of erotic love and sex?

I'm quite certain that transcending cancer and the 70-year lifespan does not threaten anything I value about Humanity 1.0. I also look forward to a world in which every child can ace the calculus class I dropped out of, and I think we could do without any schizophrenia and depression.

But a world in which no one every felt the urge to woo, exchange back massages and then mix body fluids in a furious acrobatic display? Is it possible that many people would choose to stop stirring their tea with their finger and seek subtler rewards? What aspects of sex and romantic love will we inevitably transcend as we become posthuman, and which are intrinsic to the liberated self-aware mind?

Transcending vagaries of erotic desire

Our culture assumes that happiness requires a healthy sex drive. Certainly depressed and sick people tend to lose their libido, and many people who want a sex life are made miserable when their body or circumstances make one unavailable.

Fortunately, in the past few decades we have made enormous progress in overcoming the physical and psychological barriers to active, guilt-free sexuality. We now assume that sexual activity is normal for everybody from children (at least masturbation) to seniors, and we openly discuss sexual dysfunctions.

We now have booming use of Viagra, joined now by several more drugs that give men erections. Research is progressing on the use of testosterone patches to increase libido in women and drugs that directly increase vaginal lubrication and sensitivity. Medical therapies that suppress libido, such as Prozac for depression or castration for prostate cancer, are being replaced by alternatives which maintain sexual function.

In the long term, as we learn to control the brain chemically, genetically and mechanically with nanotechnology, it seems certain that everyone who wants sexual desire will be able to turn such desire on.

Conversely, we will be increasingly able to turn sexual desire off. In nine US states, and in a growing number of countries, rapists and sex criminals are given the option of reducing their sentences and being released into the community if they undergo chemical or surgical castration. Eliminating testosterone production by removing testicles or giving regular injections of testosterone-suppressing drugs eliminates sexual fantasies and urges for almost all violent sex offenders. One German study found that while 43% of untreated sex criminals were repeat offenders after release, only 3% of those who had been surgically or chemically castrated committed another sex crime.

With further, more detailed, mapping of brain function and more sensitive tools, we will be able to reroute sexual desire from inappropriate or unattainable targets. That kind of therapy will allow us not only to rehabilitate sex criminals, but redirect our unrequited passions for coworkers, students, priests and ex-boyfriends, not to mention for their feet, underwear and whips. Genetic predispositions for homosexual or heterosexual desire will be "fixable" before birth or after birth. (Fortunately, the religious fundamentalists most likely to use gene tweaks to make their kids straighter are probably going to be opposed to gene tweaking their kids at all.)

Not just lust, but the amorphous ball of feeling called "love" itself is a biochemical phenomenon, amenable to manipulation. In Anatomy of Love, anthropologist Helen Fisher summarizes research arguing that love is composed of three biochemical process. The first process, driven by testosterone, is lust. The second process, infatuation, is controlled by dopamine, norepinephrine and phenylethylamine -- amphetamine-like chemicals that produce feelings of euphoria. The lust and infatuation chemicals peak after a year, and for the lucky few relationships that survive their decline a new biochemical response emerges based on oxytocin, vasopression and endorphins, which produce feelings of intimacy, trust and affection.

With better control of our brain chemistries we will not only be able to maintain or suppress lust, but also modulate the neurochemical bases of the subtler emotions we associate with love. We might be able to take pills to sustain feelings of romantic love and induce feelings of intimacy, or suppress them when they are directed at the unattainable.

As always, the question with these new technologies is not whether they are good or bad in themselves, but whether they will be used by free individuals in a free society, or when necessary on sex criminals. Testosterone to overcome sexual dysfunction in women is great, for example, until it become obligatory for women who don't want to have sex with their husbands.

In general I have faith in the utilitarian dictum that more knowledge and power over the conditions of our lives will lead to greater happiness. If that means some people suppress desires in situations we find exciting, such as convents, while others jack up desires in situations we find disturbing, such as shoe stores, that's the price to pay for knowledge, freedom and happiness.

Transcending romantic love

According to some accounts, the idea of romantic love was only invented 900 years ago by French poets, who bamboozled the rest of the world with their mythology of eternal, monogamous love.

This may be a little facile as psycho-history, but it is clearly true that modern ideas and expectations about love and monogamy place far more weight on the heterosexual dyad than in the past.

The majority of all human societies have been polygamous. And in most monogamous cultures men, at least, have been expected to pursue extramarital relationships of varying degrees of openness.

A mounting body of ethological and sociobiological research suggests that both human males and females, like our primate and mammal cousins, are genetically inclined to have multiple partners. Based on all this evidence Helen Fisher writes in Anatomy of Love that the primordial human "blueprint" is for a serial set of pair bonds lasting about four years -- long enough to raise a child to toddlerhood -- with clandestine adultery on the side.

The modern victory of monogamy can be seen as a very unnatural suppression of our non-monogamous biological natures. That the divorce rate is relatively low and only one American woman in eight and one American man in five have at some point sought carnal comfort outside of their marriage shows the power of culture over nature.

Why not return to some modern version of polygamy, some form of open, acknowledged sexual sharing, as advocated by the sexual revolution and the polyamory movement?

In 1990, after a dozen years of failed experiments in non-monogamy, I wrote an essay called "Monogamy as a Prisoners Dilemma: Non-Monogamy as a Collective Action Problem" that attempted to answer the question of why all of the late 20th century sexual revolutionary experiments with non-monogamy or plural marriage, my own included, had failed.

One obvious difference between a liberal college campus in the 1980s and a troop of polygamous orangutans or a polygamous village in the Amazon or a 16th century Puritan village is women's freedom. Until their 20th century emancipation, most women were not able to choose who they would marry, or when they would leave a marriage.

For instance, one theory links the rise of monogamy to the rise of patriarchal democracy; monogamy spreads women around so that there is one woman per man. My essay proposed that, when both women and men were able to freely choose the relationships that maximized their happiness, most participants in non-monogamous triads would defect to maximize their pay-offs with undistracted partners, unraveling even the most determined non-monogamous subcultures.

I suspect that the attractions of polyamory will grow in the future, however. After my essay went up on the Web I began to receive email from the growing polyamory movement, each missive adamant that I was wrong about the structural inevitability of monogamy.

One reason they offered for the growing success of polyamorous triads is that some people's lives are so busy and complicated that partial, non-exclusive relationships are all they want. And if there is any futurological certainty it is that our lives will grow in complexity and compartmentalization.

Another factor certain to challenge the myth of eternal love and increase the incidence of serial monogamy and polyamory is the radical extension of human lifespan. The commitment to love only one person unto death seems a lot less plausible if you have 200 years ahead instead of 50.

As we continue to tease apart church and state, and increase the sphere of personal liberty, it seems inevitable that we will also eliminate the heterosexist and dyadist assumptions of current marriage law.

The spread of legal gay marriage in Europe, and its slower adoption in the US, has started to rationalize marriage as a social contract. Constitutionally laws against polygamy will also eventually fall, since they are clearly based in religious discrimination.

Eventually, I foresee co-housing and co-parenting contracts replacing civil marriage, contracts which recognize the bonds between small groups of people who have made commitments of some duration. I'm sure many people will still say vows in front of priests and rabbis for centuries to come, pledging their eternal love. But hopefully the democratic state will stop treating these dyads as the only legitimate lifestyle option.

Transcending body gender

Another thing we are already transcending is biological gender.

For those who feel they were born in the wrong gender we can give or take away breasts, construct new genitals and add appropriate hormones. Using gene therapies we will be able to ramp up testosterone or estrogen production, and selectively suppress sex-linked genetic traits, making hormone treatments unnecessary. Once we have perfected tissue cloning and genetic engineering, say in 50 years, we will be able to craft new, fully functional sexual and reproductive organs for transsexuals.

But the transgender movement has quickly moved beyond simple female-to-male and male-to-female transsexualism, in which the "gender dysphoric" was expected to adopt a stereotypical gender role and sexual preference.

Today's transgender movement is a roiling, radical critique of the limits of gender roles, with folks living in totally new categories, such as non-op transsexual, TG butch, femme queen, gender-queer, cross-dresser, third gender, drag king or queen and transboy. A person with breasts and a penis may dress and identify as a woman and have a sexual preference for women. In the 21st century all the aspects of sexual dimorphism are up for mix and match to suit our psychological needs and aesthetic preferences.

By the 22nd century, when we are facing indefinite life spans, tweaks to biological gender will become increasingly common, to stay in fashion, to improve your chances in life and love, or just out of curiosity.

We already have men getting penile implants, and women having cosmetic surgery on their genitalia. Why stop with just a cosmetic enhancement, or swapping your genitals for those of another sex, when you could have a penis with the responsiveness of a clitoris, or some entirely new sexual organ? The possibilities will be endless.

Transcending body sex

Body sex itself is likely to become a minor and infrequent aspect of our erotic experience. There are some short-term reasons and some long-term reasons for the declining use of the meat-puppet in romantic play.

In the short-term, while we struggle to conquer infectious diseases, the threat of AIDS and future sexually transmitted plagues will keep body fluid contact a hazardous pastime. Also in the short-term, until we have therapies that make seniors as healthy and horny as young adults, the growing senior population will reduce the average number of sex acts per head. As reproduction becomes divorced from sex, through contraception, in-vitro fertilization and artificial wombs, those who want children can have them without messing around with body sex.

The growth of electronically mediated sex will also presumably reduce the number of flesh-to-flesh sex acts. There are millions of people in the industrialized world who spend significant amounts of time and money on Internet porn, sex chat, voyeur cams and interacting with sexual partners through Web cams and audio interfaces.

These media will soon be joined by "haptic" and "teledildonic" equipment that will communicate a partner's caresses and allow you to feel them. Extrapolating to the latter 21st century, when full nanotechnology-based virtual reality is in use, we will be able to have as high-bandwidth a sexual relationship electronically as in the flesh. That will probably mean a lot more casual e-sex and more commercial e-sex. But for those special someones it will also mean more profound sex.

Doing the nasty in nano-neuro VR will be far more intimate than in the flesh. We will be able to morph our genders, species, ages and numbers in VR, and open ourselves up to forms of tactile and emotional sharing that are impossible in the flesh-to-flesh.

We can hold an orgy on the moons of Jupiter, on lambskin rugs, with cherubim as an attentive audience. When we are fully wired into one another's brains, body sex may seem no more intimate than a handshake, something one does for exercise with casual acquaintances. We will reserve fully immersive mind-melds for only those special half-dozen folks in our plural marriages.

Direct control of our brains will also mean that masturbation will be a lot more direct than the current manual methods. We will be able to directly stimulate our sexual pleasure centers pretty much invisibly, and as often as we like. Luckily we won't have to drive our cars manually anymore, or things could be very dangerous on the road.

But faced with the uncertainty and security risk of letting some new person into your head, versus just thumbing your own button, more people may opt for a life of single self-stimulation.

So does sex have a future?

I think the abbot was probably right about body sex, which will be about as exciting as stirring tepid tea with your finger. But that's because we will be reaching out and stirring our own and our partners' brains with our fingers, and this is sure to be very exciting indeed.