Sometimes what looks like friendly behavior is really an attempt to get one's neighbor eaten by a wolf before oneself. Sheep, for instance, seem cozy enough in their flocks. What's a better way to travel than surrounded by 100 percent merino? But the real reason they stick close to their neighbors is to save their own woolly rear ends.
The question of what motivates seemingly community-minded animals is a classic one in biology. Do the birds in a flock, or the fish in a shoal, just enjoy each other's company? Do they rely on each other's eyes to spot a predator before it gets too close? In an often-cited 1971 paper, British evolutionary biologist W. D. Hamilton suggested that the answer was simple geometry.
An animal never wants to be the nearest potential prey to a predator, Hamilton said. To increase its odds of survival against a lion, a wildebeest ...
