|BUSINESSWEEK ONLINE : AUGUST 30, 1999 ISSUE|
During the next 10 years, scientists may discover startling information about the origin of life on our planet and the possibility of life elsewhere
In 1966, Russian and British scientists made a most improbable discovery: They found a huge fresh-water lake entombed under the two-mile-thick east Antarctic ice sheet. It was the size of Lake Ontario but much deeper, reaching depths of 1,650 feet. Pressure from the weight of the ice sheet above it kept it liquid even though its temperature was a few degrees below freezing. Geologists and seismologists delighted in the discovery, but it was biologists who saw the unique opportunity the lake presented. Lake Vostok, as it was named, has been isolated from the earth's surface for eons. The water in it is probably a million years old. Biologists quickly recognized that the lake could harbor creatures unknown anywhere else on earth. No sunlight reaches the lake, but microbes can live independently of the sun. And if the lake sits on a volcanic rift, the energy from underground heat vents could give rise to a thriving community.
COAL BLACK. ''The lake could really replicate conditions you might see during the evolution of life on earth, on Mars, or on Europa, one of the moons of Jupiter, where we know there's an ice sheet with water underneath it,'' says John Priscu, a microbial ecologist at Montana State University. A project to drill into the lake was abruptly halted until a global consortium of scientists can decide how to penetrate the lake without contaminating it.
Lake Vostok provides a unique opportunity to study life in extreme environments. Only a decade or two ago, many biologists would have guessed that life could not exist in the coal-black currents of a sub-freezing underground pool like Vostok. But recent discoveries of life in boiling geothermal cauldrons, natural sulfuric acid pools, and other extreme environments have changed expectations dramatically.
''I've done a 180,'' says Priscu. ''I was a skeptic all the way.'' That changed when Priscu went to Antarctica and found ancient microbes living in ice layers in the McMurdo dry valleys, a region only a little warmer than the surface of Mars. ''In the next 10 years, we're going to see more information turning up about extraterrestrial life, and about the origins of life on our planet,'' he says. Many of the microbes found contain exotic enzymes of great practical value in, say, high-temperature industrial processes.
Studies of these life forms are also changing scientists' conception of life. The eruption of life on earth was once thought to be a wondrous consequence of earth's unique position in the solar system--close enough to the sun to draw warmth and energy, without becoming a crisp briquette like Mercury or a boiling Venusian hothouse.
Now, it seems, living organisms do not require such singular circumstances. Many biologists now think it likely that some sort of life--most likely, microbes--will be found on other planets, and even on moons and asteroids.
Thomas Gold of Cornell University, for example, has put forth the controversial notion that rock strata deep underground, at high temperatures and pressures, are teeming with microbial life. ''The total amount of the microbiology at that depth may well be more, in volume, than the total amount we have on the surface,'' Gold says. Underground life might be common throughout the solar system--it is humans, scraping out a living on the cool, desiccating surface, who are living in extreme conditions, he says.
Many biologists dispute Gold's arguments. They say microbes cannot survive at excessively high temperatures and pressures. Gold says he has found microbes at extreme depths, but critics say the deep-earth samples could have been contaminated with organisms from the surface or shallower depths. There is no question, however, that the discovery of life on the fringe, in various extreme environments, is transforming biology, and lending urgency to the search for life on other planets.
Many of these organisms are part of a newly discovered branch on the tree of life. Called archaea, they share properties of bacteria and higher organisms--and they have some characteristics all their own. Studies of some of these organisms have revealed an unexpected role for certain cellular proteins that are also present in human beings, says Jonathan Trent, a biologist at NASA's Ames Research Center in Mountain View, Calif. ''It's a source of inspiration, of reveries about what life is capable of,'' Trent says.
When the drill in the Antarctic ice reaches and penetrates Lake Vostok, some time during the next few years, it will be part of the beginning of a new voyage of discovery, reminiscent of the exploratory sea voyages of centuries past. No one can say what the new voyagers will find until they return to tell us.
By PAUL RAEBURN
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