When asked to recount his closest brush with death, Douchan Gersi hesitates only to decide which one. "In Borneo, I'm out in the middle of nowhere," he says in a whisper. His broad face framed with stringy long hair and a stubby beard, he leans close to heighten the suspense.

"We fall into a deep waterfall. We are lost ... In the night I buried myself in the mud because it was too cold ... I was eating leaves, the same leaves as those eaten by the monkeys ... Sometimes I was waiting for a holy vision to come and take me out."

Gersi had set out in search for the primitive tribes in a restricted and thick Borneo jungle in the late 1970s. Instead, he found himself -- for the umpteenth time -- fighting to stay alive against all odds after being abandoned by his native porters and separated from his two companions by wilderness mishaps. The 40-year-old Czechoslovakian-born explorer and filmmaker stumbled alone into a Dayak tribal campsite, dazed by eight days of naked and famished wandering.

"I smelled the smell of burning meat," Gersi recalls. "And I'm standing in front of a batch of warriors ... with machetes and weapons like blow guns that can be used as spears. And I just flashed, 'Boy, oh boy, all this for nothing.' I got on my knees and started to cry."

The five long-haired Dayak warriors, covered with tattoos and wearing red loincloths, were a muscle twinge from killing Gersi. One of them left the group to circle around the nearby jungle to make sure Gersi was alone. The others stood tensed and motionless. Gersi knew that killing him was neither immoral nor forbidden to them. By the rules of the jungle, it was only a matter of protecting themselves and their tribe.

"I tried to show that I was hungry," he says. "One guy was so close to me I could see that he was scared ... We were all scared of each other. They generally have betel in the mouth and chewing, but they were not moving their mouths. If a single leaf would fall behind me, it would be my end. We were there for minutes, minutes, minutes. Finally the other guy came back. The one nearby me spit some red saliva and I knew they would not kill me. They {motioned} me to come over and eat."

There is evidence that suggests some people are biologically keyed toward sensation seeking. They can't help their desire to take physical and even death-defying risks. Scientists have shown increased interest recently in that mentality; in part, because, while the number of people who unexplicably choose to participate in hair-raising adventure is still small, it is growing.

Whether that growth is the product of a society that fields too many of its thrills vicariously, or of a generation of office dwellers aching for some honest-to-goodness goose bumps, the search for dangerous excitement that surpasses common sense has been documented.

A survey conducted last year by the President's Commission on Americans Outdoors determined that more Americans are taking up "risk-adventure" activities -- from skydiving and mountain climbing to white-water rafting and deep-sea diving. It counted 16 percent of U.S. adults as "excitement-seeking competitives."

Another 1986 survey, by the advertising firm D'Arcy Masius Benton & Bowles Inc., found that while more than two-thirds of the 1,500 Americans who were questioned satisfy their basic needs for adventure by watching television, most still fantasize about themselves as being trailblazers and devil-may-care travelers. In terms of taking risks, whether we act on our daring impulses or turn on the tube, most of us at least like to think of ourselves as keeping up with the Indiana Joneses. The top adventure fantasies rated in the survey: going on a safari and traveling to mainland China.

But for Douchan Gersi, life-threatening risk is more than a heart-palpitating distraction from ordinary life. He doesn't fantasize about adventure; he practices it. For scientists investigating the willing embrace of danger, Gersi falls into a category of adventurer who acts because of risk -- not despite it.

Flirting with the final heartbeat, says Gersi, is a means of self-affirmation. He believes that pumping adrenaline is to the spirit what pumping iron is to muscle: To risk and survive is to strengthen one's self. Unlike weekend hang-gliders and hot-air balloonists, Gersi says destiny, and not choice, led him to seek the adventurous life.

"Destiny put me when I was very very young into the mood of adventurer," says Gersi on a recent visit here to promote his book, Explorer (Tarcher, $18.95). The multi-city tour had to be rescheduled more than once because Gersi was being held hostage by an irate hotel owner in Morocco. A primary investor had backed out of Gersi's latest project -- an action-adventure movie about Afghanistan -- leaving unpaid almost three months of bills by his entire production crew. True to form, Gersi escaped an imminent stay in a Moroccan jail when the sympathetic hotel manager helped to get him out of the country.

Gersi's life, in fact, practically began fleeing a country. His parents were wealthy Czechs who in 1947 decided to leave their home in Bratislava before the Soviets closed the borders. They packed up their infant boy with the belongings they could carry and dodged around Eastern Europe until they landed on a boat headed for what was then the Belgian Congo.

By Gersi's account, his father had had enough of civilization and decided to settle the family on an African farm in the middle of present-day Zaire. Childhood for Gersi was jungle life. Beds had to be checked nightly for snakes, shoes for scorpions. The birds and animals of the jungle were his playmates, until he was 12 years old.

Then, in 1959, his father became seriously ill and the family moved to Belgium. That same year, the fight for independence broke out in the Belgian Congo and the Gersis lost all their possessions. They became refugees of the United Nations. At age 18, Douchan Gersi was hired as an assistant to a documentary filmmaker and learned the trade. Later, he traveled with another filmmaker to the Philippines and stayed after the film was shot to seek out the Apayao, a tribe of headhunters on North Luzon Island. That discovery (he became blood brothers with one headhunter) lent him credibility as an explorer back in Europe. At 23, Gersi left Brussels, creditors in hot pursuit, to make his own documentary on the Tuareg, the "Blue Men of the Sahara." Ever since, he has lived from one film to another, each exploration -- from New Guinea to the Amazon to Timbuktu -- paying for the next.

Once, while visiting with the Masai tribe of East Africa, Gersi was asked by the chieftain to prove his courage by stopping a charging elephant. "I thought he was joking," recalls Gersi. But to refuse would be to jeopardize the relationship he had developed with the Masai. Gersi didn't know how to stop an elephant.

"I was just walking and an old Masai came over and said, 'Everybody is talking you are going to stop an elephant tomorrow ... How do people in your country stop an elephant?' I said I wouldn't tell him, and I asked, 'How do you do it?' And he told me."

The next day, when Gersi and the Masai tribesmen came upon an angered elephant, he did what the old man had told him. "Their way is to make yourself small while the elephant is attacking, because elephants can't see very well," he says. "And when the elephant is 15 feet away, you jump, scream and thrash your arms. He stops, errrrrk, like in a cartoon." Afterward Gersi found out the strategy works only when the elephant is attacking head up and ears wide open. An elephant charging head and ears down doesn't stop.

Why does Gersi do such things? "I need to fulfil my need for adventure," he replies simply. His broken English turns out occasionally odd phrases describing always extraordinary circumstances and making him sound like a poet. Some of the dramatic accounts are so bizarre as to be suspect, but his steely eyes convince that one shouldn't quibble over facts when examining primordial truth.

"To do what I do when I go away," Gersi says, trying to explain his risk impulse, "I'm getting rid of my skin. My skin is my identity, my feeling, my religion, my education, my everything. It is a filter ... you build a kind of envelope to protect yourself.

"The problem keeping in this envelope is the references that you are taking with you -- references on faith, on beauty, on what is dangerous and what is not -- these are safe references. I get rid of them. I will not have judgment. I will not have disgust. I will not have rejection ... I try to get the most primitive of myself.

"Then you don't need words anymore to communicate, because these people can smell you and you can smell them. You reach a point where because you don't have this protection of culture, they can smell if you are good or bad. And you just can scream silently the right to be alive there with them, the right to exist, the right to be accepted."

The first and last time Gersi failed to shed "his skin" was during his youthful expedition in the Philippines. "I see the dog {cooking} in this iron pot ... and I was vomiting," he says. "That almost was my life there, because they stopped smiling. I started to insult them. I was not chomping on the food and they didn't like that. So now I reached the point where whatever {the food} is, I don't think. Usually I don't try to know what it is before I eat it."

When he's back in Los Angeles -- now the base for his explorations, book writing and latest adventures in making feature movies -- Gersi says he is in constant culture shock. "When you live with people where the first message of life is to live every day as if tomorrow will never exist," he says, "you take your time. Taking time to live is taking time to appreciate simple silence as better than any kind of talk, or watching a flower, or watching a guy wash the windows on a skyscraper and wondering what he is thinking.

"Strange thing is, when I come back here, I need the other extreme of adventure -- from nothing to good wine, good beer ... and I want to enjoy everything I am doing. So I am now playing myself into Hollywood as I would go into a jungle of headhunters. Their rules. The rules of the system. Now I would like to have a credit card, I would like to have a lawyer, I want to have an agent."

Since Gersi lives the life that other people fantasize, what are his fantasies? "I have one big dream," he says. "Jungles and rain forests are in danger in New Guinea, Africa, Asia, South America, everywhere. But who cares about the people living there? Nobody cares. It's time for man to save man."

Gersi believes that if Jacques Cousteau can raise millions of dollars to save underwater life, he could raise money to save the primitive tribes -- people of tradition, he calls them -- from industries that sentence them to death by ravaging their jungles.

"By living tradition repetitiously since the beginning of humanity, they have kept answers to many of our questions," says Gersi, who wants to lease or buy parts of jungles as tribal sanctuaries. He says it would be the greatest of his adventures: "I have not dreamed about it, I have lived it. I can't stop it now."