Tropical rainforests may cover only two percent of the planet's surface but they're home to half of all its species, including humans. Nevertheless, surviving in this hostile environment demands both skill and an intimate understanding of the jungle ecology. In the last 50 years alone, half the planet's tropical forest has been cleared with as many as 100 species becoming extinct every day, often before they have even been discovered by science. Unless something is done to stop it, much of the world's tribal knowledge and customs will inevitably go the same way.

注
• ecology 生態系（生物と環境との関係）
• tribal 部族の; 種族の