The Amazon basin region is home to about 2. 5 million insect species, tens of thousands of plants, and some 2, 000 birds and mammals. To date, at least 40, 000 plant species, 3, 000 fish, 1, 294 birds, 427 mammals, 428 amphibians, and 378 reptiles have been scientifically classified in the region. One in five of all the birds in the world live in the Amazon rainforest.
The warm and wet forest has been in existence for at least 55 million years, and thrived even during glacial periods, allowing for the evolution of an unbelievable diversity of species. Radiocarbon dating (放射性碳定年法) has revealed trees of 10 centimeter in diameter to be more than 300 years old, and some trees over 1, 000 years old, indicating that untouched forests can experience unbelievable longevity.
The first human inhabitants are thought to have settled in the Amazon region about 11, 200 years ago. European explorers arrived in the 16th century, bringing diseases which traveled faster than the explorers themselves, killing perhaps as many as 90% of the indigenous inhabitants (土著居民). By the late 17th century the Amazon basin was controlled by Portuguese and Spanish explorers.
The Amazon rainforest has been described as the lungs of our planet because of its important role in recycling carbon dioxide into oxygen. But due to deforestation (滥伐森林), rainforests now cover less than 5% of the Earth's land surface, and experts believe that this is a big contributor to global climate change. Severe deforestation began in the 20th century, with 587, 000 square kilometers lost up to the year 2000. Most deforested land is used for grassland to raise farm animals and agriculture. The addition of transport routes has led to increased settlement and deforestation, and at the present rate, scientists estimate that the Amazon rainforest will be reduced by 40% in two decades.
