Horseradish, onions and caffeine all activate a group of chemical receptors that can trigger a pain signal. Turns out the same receptors exist in fruitflies, mussels, corals and mule deer. Why has this receptor survived a half-billion years? Because it protects against toxic chemicals – even if they taste good in small doses!

Changes in the junctions between nerve cells determine how well a bird will learn to sing. Regular change in these junctions helps the bird remember the song of its species, which it needs to learn to reproduce that song. Study could explain why older people have such trouble learning a new language.

Do new species arise because so many niches are available in a new habitat? Or do they arise because newcomers have multiple talents for survival? A new study points to traits that enable success in the new location.

To hide from hungry fish, this animal houses luminous bacteria. But what prevents the bacteria from reproducing and killing the squid? At last, a genetic a balancing mechanism is revealed.

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?

Why do women have better sense of touch? It’s all in the size, and big isn’t better…

Turkeys got help for 75 years from conservation agencies. Coyotes spread across half the country all on their own. Why have these animals succeeded? How have they changed the environment?

Ultralight aircraft are guiding crane chicks toward Florida wintering grounds. Dangers remain, but it’s a step ahead for Americas’ largest flying bird, once reduced to 21 animals.

Imitation is a social glue in human society. We like people who imitate us. We call them friend. We will even tip them better! A new study finds similar responses in monkeys…

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.