In many parts of the world, pigs are used to locate truffles. Dogs can be trained to find truffles, but pigs find them with no training at all. Why are pigs so good at finding them?
Truffles spread their spores when animals eat the truffle. When the spores are ready, the truffle releases chemicals that smell like a chemical found in the saliva of male pigs. This smell is very attractive to female pigs, leading them straight to the ripe truffles. Unripe truffles have very little taste and very little smell, so the pigs ignore them until they ripen. The pigs also learn quickly that truffles are very tasty treats, which is why more and more truffle hunters are switching to dogs, since dogs will gladly trade a truffle for a doggie treat.