Rainforests are divided into different strata, or layers, with vegetation organized into a vertical pattern. Only the emergent layer is unique to tropical rainforests.
Tropical rainforests have existed on Earth for hundreds of millions of years. Most tropical rainforests today are on fragments of the Mesozoic era supercontinent of Gondwana. The separation of the landmass resulted in a great loss of amphibian diversity while at the same time the drier climate spurred the diversification of reptiles. The division left tropical rainforests located in five major regions of the world: tropical America, Africa, Southeast Asia, Madagascar, and New Guinea, with smaller outliers in Australia.
Rainforests are divided into different strata, or layers, with vegetation organized into a vertical pattern from the top of the soil to the canopy Each layer is a unique biotic community containing different plants and animals adapted for life in that particular strata. Only the emergent layer is unique to tropical rainforests, while the others are also found in temperate rainforests.
Tropical rainforests have harboured human life for many millennia, with many Indian tribes in South- and Central America, who belong to the Indigenous peoples of the Americas, the Congo Pygmies in Central Africa, and several tribes in South-East Asia, like the Dayak people and the Penan people in Borneo. Food resources within the forest are extremely dispersed due to the high biological diversity and what food does exist is largely restricted to the canopy and requires considerable energy to obtain.
Some groups of hunter-gatherers have exploited rainforest on a seasonal basis but dwelt primarily in adjacent savanna and open forest environments where food is much more abundant. Other peoples described as rainforest dwellers are hunter-gatherers who subsist in large part by trading high value forest products such as hides, feathers, and honey with agricultural people living outside the forest.
Cultivated foods and spices
Yam, coffee, chocolate, banana, mango, papaya, macadamia, avocado, and sugarcane all originally came from tropical rainforest and are still mostly grown on plantations in regions that were formerly primary forest. In the mid-1980s and 90s, 40 million tons of bananas were consumed worldwide each year, along with 13 million tons of mango. Central American coffee exports were worth US$3 billion in 1970. Much of the genetic variation used in evading the damage caused by new pests is still derived from resistant wild stock. Tropical forests have supplied 250 cultivated kinds of fruit, compared to only 20 for temperate forests. Forests in New Guinea alone contain 251 tree species with edible fruits, of which only 43 had been established as cultivated crops by 1985