What made scientists think animals could be made to work for us one day? When does the trainer usually give the animal a piece of candy or fruit? What may many different animals be trained to do if they know they will get a reward? What kind of animal can be used to guard a house? What will the pigeon do when it sees a ball which looks different from others? How long does it take to train a pigeon to inspect a steel ball? How many balls can one pigeon inspect an hour? What may apes do one day in the future?