The Cleanup Crew

High above the plain the next day, Polly slid into a slow spiral of vultures and rode the warm rising air with them. Her small green body looked almost silly among those huge brown wings, but the vultures made room. Going up cost none of them a single wingbeat. The plain turned gently below, and her round black-rim glasses flashed in the sun.

Vultures run the fastest news service in the Serengeti. Each bird can spot a meal from kilometres away, but the real trick is that they also watch each other. When one drops, its neighbours see it and drop too, and their neighbours follow, until birds are arriving from places so far away they could not possibly have seen the food itself. News travels across the whole plain without a single sound.

The smallest workers are down in the grass. Dung beetles roll balls of dung many times their own weight, food and nursery in one package. When a beetle needs to roll in a straight line at night, it climbs on top of its ball, turns a small dance, and checks the bright stripe of the Milky Way across the sky. Scientists proved this, and it remains one of the best facts anywhere: a beetle that steers by a galaxy.

By evening Polly understood the system. Nothing on this plain is wasted, and nothing is without a job. The grass feeds the herds, the herds feed the hunters, and everything left behind feeds someone smaller. She flew home across an orange sky, taking the long way, in no hurry at all.