When I was in the tenth grade I fell in love with Wendy and Laurie Chessler. For a few weeks, I loved both of them. They were identical twins--almost nobody could tell them apart. This made it harder for me to decide. I heard from Laura Bracco (who heard it from Barbara Shabbat) that both Wendy and Laurie had crushes on me. So I had to make up my mind. It took me a while to figure out which one I loved more.

Wendy and Laurie went to the public high school and I went to the Catholic high school. They had only recently started hanging out with our gang. So I didn''t know them very well. They were both very cute, in almost exactly the same way. Even in their voices, gaits and mannerisms, they were like echoes of one another. Almost.

Ultimately I came to feel strongly that Wendy was the one for me. I learned that Laurie was a bit demure and Wendy just slightly bolder. Laurie was sweet but judgmental, where Wendy tended to shrug her shoulders--yet she had an edge to her that her twin sister did not. The more I got to know them, the more I realized that the twins were subtly but deeply different.

I learned some important things about love and friendship during my brief affair with the Chessler twins. I think I may also have experienced something about the mystery of genetics.

The almost-matched set of genes that hard-wired these girls as duplicates was only off by a beat. In trying hard to isolate that beat, I had to ignore their apparent similarities. And I did it. With the limited tools of a 16-year-old, I had homed in on something about Wendy''s nature that I preferred.

Genetically, all humans are 99.9 percent identical. Of the 30,000 bits of data that make up our DNA, only a few hundred are ours and ours alone. With twins like Wendy and Laurie, only a couple of genetic traits are unique. But apparently that was enough for me.

Of course, this analysis only applies if you abandon romantic notions of True Love (guided by Cupid and the other gods and goddesses), not to mention modern ideas about social dynamics, in favor of a blind belief in the power of the DNA code. But to many of the world''s leading scientists, this millionth-of-an-inch-long strand of protein determines an awful lot of who we are and even what we do.

One Small Molecule

The human DNA molecule--four chemicals paired variously in a spiraling "double-helix" patterned protein molecule--is more than the recipe for our living organism, it is also the cook and the kitchen. It is a map of the body, but in this case the map creates the territory. The human genome tells the body how to produce a liver and a hand and a brain, and then orders the way those organs function--even, according to a controversial theory, down to determining human behavior. DNA is also the engine of evolution--the journey from nematode to ape to molecular biologist occurred according to changes inside DNA molecules.

Scientists working in the field of DNA research believe, in the words of science writer John Catalano, "that a chicken is simply an egg''s way of creating another egg, a human being a gene''s way of replicating itself."

Scientist, author and cyber-Renaissance man Stewart Brand likes to think big and way outside the box. Schooled as an ecologist, he is nevertheless most well known as the editor and publisher of the 1,200-page Whole Earth Catalogue, which won him a Pulitzer Prize in 1972. That project, and the subsequent CoEvolution Quarterly and Whole Earth Review, brought together radical ideas from disparate fields including biology, computer science and organic gardening. Brand has since expanded his work to include plans to build a 10,000-year clock and to inventory all of the species in the world, as well as a global business network.

Big-thinker Brand will be in Monterey this weekend to participate in "The Future of Life" a three-day colloquium on DNA and genetics hosted by Time magazine. He will be joined by 47 cutting-edge fellow big thinkers, including James Watson who, along with Francis Crick, discovered the structure of DNA 50 years ago, and Craig Vetter, who, just 18 months ago, helped complete the mapping of the human genome--the molecular code that may determine everything from our eye color to our taste in art.

Brand believes the conference''s title is appropriate. Because of Watson''s discovery and Vetter''s work, a new branch of science and medicine has emerged that Brand (and practically everyone else) believes will revolutionize the world.

Time magazine proclaimed, in this week''s issue, that "cracking the DNA code has changed how we live, heal eat and imagine the future." To prove this claim, Time has assembled the leading experts in many fields of study, including scientists working in stem cell research, gene therapy, cloning, and various other bio-technologies--professors of evolutionary theory, ethics, ecology, economics and politics, and researchers of bioterrorism, information science, agriculture, education and the growing science of genomics--people who have moved human understanding of biology, and the capacity to manipulate it, onto an entirely new plane.

The most controversial of the issues they deal with--genetically-modified foods, stem cell research and cloning--have dominated media coverage of this biological revolution, and with good reason. Genetic bio-tech''s invasion of agriculture, which began a decade ago, has already produced some alarming results and is a cause of global concern. And the mere idea of stem-cell farming and human cloning has launched a cottage industry of science ethicists.

Brand recognizes the merit of the debate, but feels that the bigger picture is being overlooked. Even cloning, to him, is nothing to fear.

"I know people who are twins," he says. "Clones are just twins. Your clone isn''t another you. Your clone would be no more fully like you than your twin brother."

Instead of focusing on the dangers, Brand points to the stunning benefits that could be had from this new technology.

He has his own pet project--he believes DNA technology will enable researchers to discover and catalogue all the species in the world.

"We don''t know even close to every species in the world; we don''t know how many species there are, and we don''t know how many we know, because they''ve never all been catalogued in one place," he says, describing the mission of his All Species Project to complete the work begun by the first modern botanist in 1735. "[Biologists] have discovered maybe 1.6 million species since Linnaeus. There are probably somewhere between 10 million and 100 million species on the planet. The best biological knowledge is still biological ignorance."

The unlocking of the DNA code gives ecologists the tools to "speciate" the living world, Brand says. Beyond this, he also points to changes in human medicine wrought by the science of genetics.

"There have been very serious biological breakthroughs," Brand says. "Imagine having a spare liver." He reports that stem-cell research and cloning technology make this fantasy a virtual inevitability.

"We are going to see the beginning of life extension," he says. "Not just life extension, but, more importantly, quality-of-life extension. Nobody is going to get too excited about living to be 150 years old if they''re going to feel the way Ronald Reagan feels right now. But what if you could be 95 and feel like someone in their 40s?

"Astounding things have already happened, and the curve of astoundingness is steepening. Strange as it all is, it''s gonna get stranger."

One Big Theory

A panel that Brand is moderating Thursday afternoon called "And What About the Other 9,999,999 Species?" features two leading lights of evolutionary theory.

Richard Dawkins, author of The Selfish Gene, is the chief exponent of the egg-then-chicken theory cited above (and also, Weekly readers take note, a squid expert). Since the death of his nemesis, Steven Jay Gould, Dawkins is the heir apparent to the legacy of Charles Darwin. His most recent book, Unweaving the Rainbow, argues not only for acceptance of the role of the gene in determining the fate of the individual and humankind, but also for a hardcore belief in scientific understanding.

"There has been a tendency among some poetic spirits to feel that mysteries lose their poetry when solved," he told writer John Catalano. His book''s title, he said, "comes from Keats, who was talking about Newton unweaving the rainbow and thereby spoiling the poetry, which I think is nonsense.

"When you explain something, you usually uncover still greater mysteries, which are even more beautiful. The unweaving of the rainbow led to spectroscopy, and spectroscopy is how we know what stars are made of."

On the panel with Watkins and Brand will be Edward O. Wilson, whom Time labeled as one of the 25 most influential scientists of the 20th century.

Wilson is the inventor of two growth sectors of contemporary study--sociobiology (which studies the roots of psychology) and conservation biology (which links ecological science and political activism). He is the man who coined the term "biodiversity," and is the prophet of its doom.

In addition to being a front-line-researcher, he is an acclaimed author--he has won two Pulitzer prizes, one for the broadly-ranging On Human Nature, and one for the tightly-focused The Ants (Wilson is the world''s leading expert on ants).

Studying insects, Wilson noted two biological forces at work: one operating within the individual organisms; the other seeming to control the swarm, or the hive, which he calls the "superorganism." He discovered the means that social insects use to communicate the needs of the group to each other. Wilson sees this information as hard-wired into all living creatures, including humans.

From his work on ants, Wilson has extrapolated far in two directions. On one hand, he paints a picture of nature as a machine in which a few natural laws account for everything--all encoded into variations on one molecule. At the same time, at the core of his mechanistic worldview lies an Organizing Principle--something like what the primitives call god (Wilson might dispute the comparison). In Wilson''s dictionary, there is no need for the word "spirit," because the sacred is woven into the physical fabric of life.

As he postulates a nature powered by one force, Wilson envisions a collaboration of scientists, activists and culture-workers teaming up to bring all that is knowable by science and the humanities together into one megadicipline. Time''s convocation this week may be a step in that direction.

"The Future of Life" conference continues today and Friday at the Monterey Conference Center, but is sold out. Even if it wasn''t, the registration fee is $1,950.