EVIDENCE SUPPORTS ORIGIN-OF-LIFE THEORY : UNDERWATER VOLCANOES FOCUS OF NEW FINDING.

Byline: Nicholas Wade The New York Times

The theory that life on Earth began around a volcano, perhaps at the deep-sea vents where molten lava boils through the ocean floor, has been bolstered by the chemical reconstruction of an essential step in the metabolism of living cells.

If the new finding is correct, it means that the recipe for creating life on a new-born planet consists of mostly lethal ingredients and would read something like this: Drop a handful of fool's gold (the mineral iron pyrites) and a sprinkle of nickel into water, stir in a strong whiff of rotten eggs (caused by the gas hydrogen sulfide) and carbon monoxide, heat mixture near the crackle and hiss of a volcano and let simmer for an eon.

Some kind of natural chemical reactions presumably preceded the emergence of the first living cells some time before 3.5 billion years ago. But the nature of these reactions, a subject known as prebiotic chemistry, has become a matter of dispute as the textbook theory, developed by Stanley Miller of the University of California, San Diego, has come under challenge.

The latest effort to reconstruct prebiotic chemistry has been made by Claudia Huber of the Technical University of Munich and Guenter Waechtershaeuser, also of Munich. Waechtershaeuser is a Ph.D. chemist who works as a patent lawyer but is respected among chemists who study the origin of life. Their article appears in Friday's issue of the journal Science.

Christian de Duve, a biochemist and Nobel Prize winner who has written on the origin of life, said Waechtershaeuser's new work was ``an extremely interesting finding which fits with the idea that life may have originated in a volcanic setting.''

``It stresses the importance of sulfur and iron, which again fits with what we know from biochemistry,'' he said.

Robert Crabtree, an expert on metals and chemical change at Yale University, said it was tough to imagine that anyone would discover exactly how life started ``but nevertheless this is an important contribution'' and one that ``could come to be seen as comparable'' with Miller's if it should prove correct.

There is a growing belief among some microbiologists that the locale for the origin of life was not tidal pools and lightning strikes, as implied in Miller's view, but in deep vents or other geothermal sources. ``We are seeing a miniparadigm shift,'' said Norman Pace, a microbiologist at the University of California at Berkeley. ``It's a fieldwide split and Waechtershaeuser has certainly been a driver.''

The classic experiment performed by Miller when he was a graduate student in 1953 seemed to solve the scientific problem of how life began, at least in broad outline. He took some water to represent the ocean, the gases methane, ammonia and hydrogen to represent the early Earth's atmosphere and sent electric sparks through the mixture to simulate lightning strikes. After several days he found that many organic chemicals typical of living cells, including amino acids, the building blocks of proteins, had formed within the concoction.

It seemed only a matter of time for chemists to figure out how the building blocks might have combined naturally into the complex molecules of life.

But taking the next steps beyond Miller's brilliant beginning proved much harder than expected. One reason is that geologists changed their minds about the composition of the Earth's early atmosphere. They now think it consisted largely of carbon dioxide and nitrogen, a far less reactive mixture than Miller used.

``I would call the conventional origin-of-life chemistry as being at a dead end,'' said Carl Woese, a microbiologist at the University of Illinois.

It was Woese who discovered that all living creatures belong to three very ancient lineages, known as bacteria, eukarya and archaea.

Eukarya is the kingdom to which all plants and animals belong. The archaea, single-celled organisms confused with bacteria until Woese's discovery, are of interest to biologists studying the origin of life because they have certain primitive features and a liking for extreme environments, like the boiling springs of Yellowstone National Park and the superheated waters that swirl from deep-sea volcanoes.

Deep-sea vents, first directly observed only 20 years ago, have become of increasing interest as a possible origin of the planet's life. These underwater volcanoes, known as black smokers, are home to a strange array of creatures found nowhere else, as well as to many species of archaea. The vents spew out superheated water laden with a black cloud of chemicals, including carbon monoxide, hydrogen sulfide and various metal sulfides.