'Jungle' is a word used to describe the densest part of a rainforest, the part that contains the most animal and plant life. The word 'jungle' comes from Sanskrit jangala, meaning 'uncultivated land'. Only 6% of the Earth is jungle but more than half of all species live there.
The most diverse habitat on earth is the jungle canopy, formed by a belt of interconnected treetops 40m above the ground. It is a completely separate ecosystem from the rest of the jungle and one we know very little about: serious exploration of the canopy only began in the 1980s. The animals that live there never need to leave it: they get their water from 'epiphytes', plants that grow on other plants and trap water in their fronds. Some parts of the canopy are so dense that it takes rainwater ten minutes to reach the ground. It is estimated that 90% of all jungle animals and plants live among its leaves.
The rainforest soil, on the other hand, is surprisingly poor in nutrients. This is because so many of the plant species are evergreen and so tend not to lose leaves, but also because the forest floor is a seething mat of insects who are unbelievably efficient at hoovering up anything that falls or dies. In terms of biomass, the ants alone weigh four times more than all the jungle mammals: there are an average of 800 to every square metre. Some species have even turned farmer, creating fungi gardens, which they tend, and prune, fertilising them with their dung and fumigating them with bacteria to keep the food crop parasite-free.
Of all the 'Jubious' theories we’ve researched, this one seems to have the strongest claim to respectability: it appears that a substantial part of the Amazon rainforest may have been created by human activity, as a giant orchard.
Amazonian soil was once thought too poor to support agriculture, but it’s now known that at least 10% of it is miraculous stuff called Terra Preta (‘black earth’ in Portuguese) that contains charcoal, bone, manure and fragments of pottery. Up to 2 metres deep in places, and accepted as human in origin, it was created deliberately over a period of 1,500 years between 450 bc and 950 ad. Rich in nutrients that last thousands of years, it has remarkable regenerative properties - so much so that it’s been suggested as a solution to the infertile land of Africa. Brazilian farmers search it out and sell it as valuable compost - but always leave some in the ground, where it retains its power. There is enough of it to cover the whole of France, or twice the area of Great Britain.
Clearing forest to make fields with stone tools is hard, so the first Amazonians opted instead to manage its immense variety, culling the trees they had no use for but retaining the fruits, nuts and palms, which brought better productivity than crops. Today, tourists are amazed at how you can just wander through the rainforest and pick fruit. Where the forest was to be cleared, they used fire, which produced soil-enriching charcoal.
Most Amazonian land can’t be seen under the jungle. When cleared, precise geometric figures called geoglyphs emerge, 2,000 - 750 years old and the size of football fields. Google Earth was used to look for more: in two weeks they found 100. To build these would have taken vast numbers of people. BBC Four’s documentary series Unnatural Histories (2011) argued that an advanced civilisation of five to six million people flourished along the Amazon in the 1540s.
Diseases brought by the Spanish, such as smallpox and flu, wiped out 90-95% of the population – by the 18th century the rainforest was empty. They left no buildings – but the soil and the geoglyphs are still there.
There are, on average, 2.4 billion ants to the square mile in the jungle.
A single acre of the Malaysian rainforest may contain as many as 100 different species of tree.
Do not call the forest that shelters you a jungle.
About a quarter of all medicines we take are made with plants that grow in the rainforest.
Scientists studying the rainforest sometimes use hot air balloons to reach the very top of the canopy.