All animals can taste, and almost all animals have the same receptors for taste, those for sweet, sour, bitter, salty, and umami (also called savory). The interaction of these receptors help guide an animal to foods that are beneficial to them and away from foods that may be dangerous. Humans are a bit different in that we have learned to appreciate some flavors that animals would avoid, like some mild bitterness and sour foods. It's a good thing that we had brave taste-testers, and later scientists, to let us know what foods might kill us.
Some animals have lost a taste sense they didn't need, like cats that cannot taste sweetness, but they still have the genes that mean they once could, back in their evolutionary line. Scientists are looking into the genetic records to find out how these tastes developed and why. It turns out that no vertebrates have ever lost the ability to taste sourness. It appears that the ability to detect sourness was useful even before animals began judging the quality of potential foods they encountered. What's really interesting is the reason why humans are attracted to sour flavors when other animals aren't. -via Damn Interesting