Take a look at the heads of the animals on these two pages. Are they all the same? Yes and no. Yes, each animal has ears, eyes, a mouth, and a nose. But no, they don't have the same kind of mouth and nose. Why? Because, through many thousands of years, the animals' bodies slowly changed. The giraffe is a good example of evolution. With its long neck, it reaches food at the top of trees. Then it pulls the branches to its mouth. Finally, with special teeth like a comb, it can quickly strip the leaves off the branches. The chimpanzee uses facial expressions for communication. For example, a mouth with closed lips can mean "I am not very happy". An open mouth showing top and bottom teeth can mean "I am frightened". Dogs and rabbits have highly developed senses of smell and touch. They communicate with each other by using pheromones (scent from their bodies). And the sensitive hairs on their faces help the animals to find their way in the dark. The hippopotamus also uses its mouth for communication. Here, with mouth wide open, it is warning another hippo and saying "Go away!". Whose mouths are these? Can you guess? They all belong to carnivores (meat-eaters). A long time ago the "king of beasts" lived in northern India, the Middle East, and even in Europe. Today, the lion lives only in Africa, and in one nature reserve in north-west India. In fact, there are very few lions left in the world. In the past, hunters killed them and kept their heads and skins as trophies. Nowadays, lion hunting is strictly controlled. This dog's mouth contains sharp teeth like the lion's. The teeth tell a story about the dog's evolution. His ancestors needed these teeth for killing and eating prey. The frog is an amphibian, which means it can live on land and in water. It is a carnivore, but it doesn't have any teeth. This is because frogs catch mainly soft animals like worms and snails. So why is a frog's mouth