We set out in the small motorboat after dark to take a look at the animals in and around the river. It's very cool and still, and in the moonlight, eerie blue reflections of the trees are cast on the water. Our torch catches the twin red glows of caiman eyes, looking our way before quietly slipping under the surface. A family of capybara clusters near the bank, ears twitching and their long, square heads breaking the water like a collection of floating, furry shoe boxes. A herd of white brahmin cattle on the bank peers curiously at the boat, gleaming like pale ghosts. Everything is different in the dark.

Then the guide says he's heard a jaguar, cuts the engine and turns out the torch. What a weight of silence! No cars, no aeroplanes, no human voices. Just the tiny night sounds of animals moving, breathing and hiding, and our own blood buzzing in our ears. History peels away: we are just Homo sapiens listening in the dark, not breathing, listening for the cat.