The truck drops us off on a dirt road, then we hike for a mile through the rainforest to reach our field camp. We carry everything with us—food, clothes, research equipment. The camp is primitive—just some corrugated roofing over wooden frames to provide shelters.

In the camp, everybody sleeps in hammocks. It’s hard at first, but before long we all sleep like babies. We bathe in a stream, and wash our clothes there, too. The food is a little monotonous in camp—we always have rice and beans, often supplemented with chicken or fish.

At dawn, we are woken by the deep, unearthly roar of howler monkeys. I don’t know how to describe the eerie sound they make, but it makes the hair on the back of your neck stand on end. It’s almost like something from another planet.

You won’t be surprised to hear that the weather is hot in the Amazon. Some days it’s so hot and muggy that I sweat just sitting down, doing nothing. We have to be careful to take a lot of water with us when we go hiking, because we can easily lose five or six pounds of water a day just by sweating.