Every hour, 3,000 acres of tropical rain forests are destroyed in order to provide the world with the things it can't live without: chopsticks and teak coffee tables and grazing space to raise crops and hamburgers for the insatiable human race.

At this rate, says University of Utah biology professor Diane Davidson, in five generations there will be no rain forests left. And when they go, they will take with them half of all the plants and creatures on the planet.Davidson, who has become an expert on rain forests, has done most of her research in the tropics of Central and South America, Southeast Asia and Australia. The rain forest is for biologists like Davidson what outer space is for astronauts: the ultimate experience and the ultimate laboratory.

The rain forests are so rich with life that in an area the size of downtown Salt Lake City you might find 750 kinds of trees, 15,000 types of flowering plants, 400 kinds of birds and 125 different mammals. But all this as well as the climate of the world is threatened by massive deforestation at the rate of 27 million acres a year.

Davidson will present an overview of this phenomenon Wednesday at 7:30 p.m. in a lecture in the University of Utah's Arts and Architecture auditorium. "Tropical rain forests: Devastation and Hope" is sponsored by the Sierra Club and the U.'s Lowell Bennion Community Service Center. The lecture is free, although the sponsors note that "any donations will gratefully be accepted and will go directly toward conserving our richest heritage."

According to Davidson, biologists estimate that about 40 percent of the world's rain forests have already been destroyed, and that within the next dozen years, only the forests of western Brazil and the Congo will remain.

It's not hard to envision a time when all that will remain will be a few rain forest "parks" tiny islands of our ecological past surrounded by business parks and condos tropical versions of Salt Lake's Wheeler Farm.

That will mean the end of a couple million species of plants and animals. "It's a problem of enormous scale," Davidson notes. The life that will die with the rain forests "is not replaceable, and it's slipping through our fingers."

In fact, the rain forests may harbor many million more species than is presently assumed, she says. "We know very little about species diversity." She points out that only recently, on the island of Madagascar, a new type of primate was discovered. The forests of South America, much larger in size and largely unexplored, are an even likelier biological treasure chest.

And if we don't even know the names of millions of species of plants in tropical rain forests, Davision adds, "you can bet we know nothing about their chemistry."

According to the World Resources's Institute, the chemicals present in at least 1,400 known rain forest plants are believed to offer cures for cancer. A drug made from the periwinkle plant found in tropical forests is being used to treat childhood leukemia and Hodgkin's disease. According to the institute, one out of four pharmaceuticals used by Western chemists comes from tropical plants. These chemicals can be harvested without cutting down the forests.

"There's an enormous potential here. We're just beginning to tap it," Davidson said.

So far, however, the world's desire for teak, mahogany and other raw materials has been a bigger priority. In Borneo, she says, the rain forests are nearly gone, felled mostly by the Japanese. "A hundred million years of evolution down the drain for chopsticks," she says with a sigh.

But logging is only one small reason why the forests are disappearing, she says. The rapid population growth of developing countries and the shortsighted means used to both feed them and keep them warm account for the real problem.

Poor populations clear the forests to farm the land but because the soils in rain forests are only rich very near the surface, within a few years the land no longer is fertile enough to support crops. In addition, once the tropical vegetation is gone, the rainfall diminishes.

Ninety-five percent of the food eaten in the world comes from just 17 plants, notes Davidson. But there are 75,000 known edible plants in the world, many of them in the very same forests being felled for farmland, she adds.

There is some hope though, says Davidson. "People are getting jazzed about this topic now," she says. News stories about the continued destruction of the forests are putting pressure on organizations like the World Bank to hire ecological biologists to help solve the problem of how to feed the world's hungry. This will not diminish the need for population control, however, she notes.

Davidson, who received her doctorate in the U. of U.'s biology department, travels to the world's rain forests to study the degree to which plants and ants have developed a co-dependency on each other.

As for the human species, it seems to be taking much more than it gives. "We are a selfish species," Davidson says, "and we treat our resources in a selfish way.

"We need to use our intellectual capacity to become the human beings we've never been before. We need to overcome our evolutionary history."