Saturday, November 3, 2001

Lecture series kicks off with
discussion on planetary life

By Helen Altonn

The co-author of a controversial science book that dispels the notion of complex life on other planets will kick off the University of Hawaii's Distinguished Lecture Series on Monday.

Peter Ward, University of Washington geologist and paleontologist, will discuss "The Rare Earth Hypothesis -- How Common are Habitable Worlds in the Universe?" at 7:30 p.m. in Room 155, Spalding Hall, 2540 Maile Way.

He also will lecture on "Mass Extinctions: Past, Present and ... Future?" at 3:30 p.m. Wednesday in the Pacific Ocean Science & Technology building, Room 723.

Both talks are open to the public.

The "Rare Earth Hypothesis," written by Ward and astronomer Don Brownlee, also at the University of Washington, has fueled an ongoing debate about whether Earth's life forms exist elsewhere in the universe.

They lay out scientific evidence, using results of geology, evolutionary biology, solar system history and cosmology, to counter an argument by astronomers Frank Drake and Carl Sagan in the 1970s that complex extraterrestrial life is common. Sagan estimated a million advanced civilizations might exist just in the Milky Way galaxy.

In "Rare Earth," Ward and Brownlee describe special conditions needed for development of higher levels of life, which they say are unlikely on other planets.

UH geologist John Mahoney said, "For many years now ... the standard model has been this hypothesis by Frank Drake and Carl Sagan who concluded, 'Yes, intelligent life, complex life, probably is extremely common in the universe.'

"Ward and his colleague made the opposite argument. They basically say, if you look at the Earth and what it has taken for life to reach the level of complexity we have here today, there's a whole chain of circumstances that have to be met for it to happen.

"There are a lot of sort of lucky chances you might say that have to be met, or it won't happen. They conclude that the probability of complex life is probably very, very low."

But they also say the probability of simple life such as bacteria, single-cell organisms, probably is high, Mahoney added.

"Conditions for that kind of life probably are common in the universe, but probably few places got beyond that, and even if they did, chances for it to survive are slim for lots of reasons."

Mahoney said Ward's big interest over the years has been mass extinction -- the topic of his Wednesday lecture. He has studied the last three of five known mass extinctions on Earth and has a NASA astrobiology grant to look for more clues to a sudden mass extinction 200 million years ago.

"Something suddenly killed off more than 50 percent of all species on Earth, and that led to the age of dinosaurs," he wrote in a paper in the May 11 journal Science.

He plans to take a research team to the Queen Charlotte Islands, off Canada's British Columbia Coast, where they found evidence from the extinction.

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