Cleaner fish remove parasites from other fish. Why do males punish females who eat the wrong food from their host? A clue to the evolution of cooperation?

The struggle between predator and prey never ends. Bats invented sonar, and now some moths are fighting back. Check out the Why Files acoustic-organic warfare, airborne edition.

We explore the sad saga of pet primates. Are these pets psychologically good for us? For them? Are humans and other primates trading diseases at home, and in the wild?

You can’t hold your eyes completely still, but what is the purpose of those tiny movements? A new study could explain why we make them — and why we seldom notice them.

Locusts live a solitary life — until their bodies suddenly change, and they swarm into clouds of destructive insects. A new study fingers the trigger for this transformation.

How does momma croc know when to dig up the young? How do the embryos know when to start hatching? The secret’s in the song…

Mice can tell the sex, mating status and identity of another mouse — all from sniffing urine. A new study of how mice read pheromones also gives insight into the human sensory apparatus…

Migration of songbirds, butterflies, turtles and seals. Where does the natural urge to move originate?

A toddler suddenly begins to learn 10 words a day. Does this reflect some innate genius for language, or could it have a less dramatic explanation? New research de-glamorizes the vocab explosion.

Are humans the only animals that will help another animal without any expectation of reward? Not according to a recent study, which shows they’re willing to help unrelated apes.