In this chapter, we're introduced to a number of different kinds of animals, including dogs, cats, and rabbits. We're also introduced to the concept of "animal sex" , which is a fancy way of saying that animals have evolved from one type of animal to another. For example, a cat might be capricious, while a dog might be sociable, but there are many other traits that make a cat or a dog different from a mouse or a bird. So, for example, cats are capricious and dogs are sociable. We also learn that a person who has evolved from a blood type to an animal sex can be classified as a "blood type" or an "estrus" . In other words, they're different from other animals in that they have different blood types and different animal sex. The narrator introduces us to some of the animals that we'll meet in this chapter. First, we get a description of blood types, then we get an explanation of estrus, and finally we get some information about the different animal traits that are characteristic of each animal . For instance, a mouse might be a capricious animal, but a cat may be a sociable animal. We learn that cats and dogs have different temperaments, but they all have the same traits, so it's up to each animal to figure out what makes them different from the other animals.