RIO DE JANEIRO — The lone survivor of an isolated tribe in the Brazilian Amazon, monitored and assisted from afar by the government for decades, looks healthy in a rare new video released this week, which shows him swinging an ax at a tree.

Anthropologists say the man, who is believed to be in his 50s, has lived on his own in the jungle in Rondônia State since other members of his tribe died in the 1990s, probably killed by ranchers.

He has become a symbol of the resilience of the more than 100 isolated communities estimated to survive in remote parts of Brazil, under pressure as farmers, miners and loggers push further into the Amazon jungle.

The National Indian Foundation, or Funai, a government agency that supports indigenous communities, tried to establish contact with the man a few times, starting in 1996. But he has responded to outsiders with hostility. In 2005, he wounded a Funai official by firing an arrow.