Pronouns are the same as nouns because they both change for number (singular & plural), case (subject, object, possessive, etc.), and gender (male, female, animate, inanimate, etc.) Nouns and pronouns can be used in almost all the same places in sentences, and they name the same kinds of things: people, objects, etc. Even though they can not normally come after determiners, or adjectives, neither can proper nouns.