Rio De Janeiro: Dramatic photographs of previously unfound Amazon Indians have highlighted the precariousness of the few remaining "lost' tribes and the dangers they face from contact with outsiders. The bow-and-arrow wielding Indians in the pictures released last week are likely the remnants of a larger tribe who were forced deeper into the forest by encroaching settlement, experts said. Rather than being "lost', they have likely had plenty of contact with other indigenous groups over the years, said Thomas Lovejoy, an Amazon expert who is president of The Heinz Center in Washington. "I think there is an ethical question whether you can in the end keep them from any contact and I think the answer to that is no,' Lovejoy said. "The right answer is to have the kind of contact and change that the tribes themselves manage the pace of it.' The Brazil-Peru border area is one of the world's last refuges for such groups, with more than 50 uncontacted tribes thought to live there out of the estimated 100 worldwide. They are increasingly at risk from development, especially on the Peruvian side which has been slower than Brazil to recognize protected areas for indigenous people. Jose Carlos Meirelles, an official with Brazil's Indian protection agency who was on the helicopter that overflew the tribe, said they should be left alone as much as possible. "While we are getting arrows in the face, it's fine,' he told Brazil's Globo newspaper. "The day that they are well-behaved, they are finished.' Contact with outsiders has historically been disastrous for Brazil's Indians, who now number about 350,000 compared to up to 5 million when the first Europeans arrived. "In 508 years of history, out of the thousands of tribes that exist none have adapted well to society in Brazil,' said Sydney Possuelo, a former official with Brazil's Indian protection. More than half of the Murunahua tribe in Peru died of colds and other illness after they were contacted as a result of development for the first time in 1996, said David Hill of the Survival International group. REUTERS NEW WORLD: Members of a recently discovered indigenous tribe stare at the aircraft from which the pictures were taken, in Brazil's Amazon region