Mammal: A mammal is a warm-blooded animal that has a backbone. This makes a vertebrate. Female mammals feed their young milk. Mammals can live in both cold and warm climates. All mammals are the only animals that have hair. mammals have a larger brain than other animals. Some mammals live a long time while others live a short time. Humans live more than eighty years and the shrew lives less than a year. Examples of mammals are humans, dogs , and whales.