The Little Inventors of the Forest

In a Ugandan rainforest, where cicadas hum and fig trees knot the sky, a small chimpanzee spots a patch of moss after rain. Instead of moving on, she plucks it up, squeezes it in her tiny palm, and presses it into a hollow in the bark to soak up water. She lifts the soggy mass to her mouth, drinks, and repeats.

The adults nearby do none of this. They don…