Pig

Pigs consistently surprise researchers. They outperform dogs and chimps on certain cognitive tasks, dream, feel empathy, and appear to experience something close to excitement when they learn new things. Their reputation for being dirty is a product of confinement conditions, not their own preferences — given space, pigs are fastidiously clean.

Facts you didn't know

• 1

  Pigs have outperformed chimpanzees on video game tasks requiring joystick control and cause-and-effect reasoning — despite having hooves and no evolutionary reason to understand screens. The research revealed that pigs understand abstract feedback loops.

• 2

  Pigs dream. Research has confirmed REM sleep in pigs with irregular breathing and rapid eye movements consistent with dreaming. Pigs stressed during the day show more disturbed REM patterns, suggesting they process emotional experiences during sleep.

• 3

  Pigs experience emotional contagion — they feel what nearby individuals feel. Pigs near distressed companions become anxious without experiencing distress themselves; pigs near happy companions become more optimistic. This empathic response is similar to what humans experience.

• 4

  A pig's nose is sensitive enough to detect truffles buried a meter underground. Dogs are now preferred as truffle hunters only because pigs like to eat the truffles and are harder to redirect once they've found them.

• 5

  Pigs can't sweat — they have no functional sweat glands. Mud-bathing is thermoregulation, not preference for filth. Given a clean environment with space, pigs will not defecate near their sleeping or eating areas. The dirty reputation comes from the conditions of confinement, not the animal.