When I decided to become a soil microbiologist, I knew that the soil could be the most diverse environment in the world, but there was minimal information regarding how extremely diverse Amazonian soils are. Today we know Amazonian soils contain more than 700 different insects and arachnids, including around 180 different species of ants and more than 80 different species of termites, five different families of earthworms and around 40% of the world’s diversity of a group of beneficial fungi denominated arbuscular mycorrhizal fungi. Most Amazonian soils are acidic with low fertility. For many years researchers, colonists and explorers believed that human populations in the Amazon region were limited to small groups with simple social organizations that live in a simple manner with little or no technological developments. However, the Amazon region has been inhabited by many ancestral indigenous communities (an approximated 10 million people before the discovery of America by Europeans) who lived in complex and populated settlements with thousands of people. They needed to produce (through hunting, fishing and cultivation) enough food to sustain these settlements, much like the indigenous communities of today. But a common denominator between ancient and contemporary indigenous communities is that they do not perceive low-fertility Amazonian soils as a constraint for food production. Most productive soils are rich in minerals that are nutrients for plants, and these minerals come from parental rocks that were also rich in these minerals. The parental material from which Amazonian soils originate are rich in kaolinite, which is a clay poor in nutrients, so the mineral portion of Amazonian soils does not supply nutrients to plants. Most of the phosphorus, which is essential for plants to elaborate proteins and energy, comes from organic matter and not from the mineral portion of soils. The acidity of Amazonian soils also...