It is appropriate, here, to distinguish between folk taxonomies and scientific taxonomy inasmuch as our current scientific classifications are the result of broad consensus amongst current practitioners of the art of naming (not without controversy, of course). But what is interesting is that, independent of this formal body of knowledge, we automatically and naturally make associations and categorize things around us.
We all agree, scientist and non-scientist, that a raccoon is a mammal. Everyone on Earth, it turns out, makes the mammalian distinction, just as we all agree that if it has fins and swims in the sea, it's a fish (in most cases).
Cecil Brown, a linguistic anthropologist at Northern Illinois University, and expert in lexical acculturation, language universals, and the comparative study of Mayan languages, has researched folk taxonomies in 188 languages, and concluded that there are nine universal classifications for living things.
Wugs (aka worms and insects)
Carol Yoon recently published a fascinating account of the history of taxonomy titled, Naming Nature: The Clash Between Science and Instinct, (W.W. Norton & Co., 2009).