PROSTITUTION MAY BE the oldest profession on Earth, but the oldest science on Earth is no doubt the study of longevity. The earliest stirrings of rational inquiry in civilizations like ancient Egypt's were bound up with the quest for immortality. And while the Egyptians may not have had National Institutes of Health grants, or immortal mummies, they certainly managed to come up with some groovy chemical compounds that preserve dead bodies for a really long time.

In San Francisco two of the oldest pursuits in the world are thriving within blocks of each other: sex workers sell their services along Sixth Street, while a biology laboratory devoted to life extension, the Kenyon Lab, was one of the first to move into UC San Francisco's new Mission Bay digs off Seventh Street. Directed by the notoriously quirky Cynthia Kenyon, the lab has been making headlines for the past couple of years with a string of discoveries involving the genetic basis for aging. While many researchers have argued that the key to extending life span is caloric restriction – essentially, starving oneself – Kenyon has proved that aging can be slowed significantly simply by interfering with the way our genomes control the processing of certain hormones.

In a recent interview in New Scientist, Kenyon said, "Longevity is evolvable. The common precursor to worms, flies, mice and humans was a very simple, short-lived animal. And to get from a worm to a human you have increased life span a thousandfold. This happened by changes in genes." Her argument is as commonsensical as it gets: given that certain animals have evolved long life spans, it follows logically that longevity is something that is controlled by genetics.

Another implication of Kenyon's work is that we don't grow old and die just because we run down like machines do. We do it because our genes tell our bodies to at a certain point – much the same way they tell us to go through puberty or to get taller as we age.

Kenyon, along with other antiaging geeks like Lenny Guarente at the Massachusetts Institute of Technology, are convinced we can invent drugs that mess around with the genes that kick off the aging cycle – in the case of humans, we're talking mostly about genes that help create parts of our cells that interact with insulin and another hormone called insulin-like growth factor. Kenyon Lab experiments reveal that if you mutate equivalent genes in C. elegans, every biologist's favorite little worm, the nematodes live as much as four times longer than their nonmutant peers.

This is exciting but dangerous news. Sure, it's cool in a nerdy way to discover that aging is controlled by genes. But more than that, it's lucrative. With a handful of other prominent scientists in the field, Kenyon is a cofounder of Cambridge, Mass.-based bio-com Elixir Pharmaceuticals, where researchers are trying to produce drugs that would extend human life the way Kenyon extended the lives of her C. elegans research subjects. If Elixir can discover such a drug, the market would literally be infinite. Everybody wants to live longer. That's the whole basis for practically every religion on our dumb, dirty planet: eternal afterlife, eternal reincarnation, etc. It's all about getting more time to be our fabulous selves.

So why does the idea of a life-extending drug repulse me? Partly it's the obvious problem that this will be an amenity for the wealthier members of our species, which is patently unfair. Why should Bill Gates get to live longer than Jim Munroe or Seth Schoen? Munroe and Schoen have done far more good in the world on shoestring budgets than Gates has done with his global corporate domination scam.

Also, I think extending certain people's lives might be nice for a few select individuals but would be extremely destructive for us as a species. Given that the human population is expanding far beyond our ability to maintain a decent quality of life for most people, doesn't the pursuit of longevity seem, well, selfish? Although the idea of taking pills to stay alive an extra 100 years is tempting, the idea of popping one makes me feel profoundly guilty.

Life is good, but only if everybody has equal access to it. Maybe someday we'll have solved enough problems in our respective societies that I can suck up the world's resources for an extra 100 years without repercussions. But we're not there yet.