For most of history, biologists used the visible appearance of plants or animals to classify them. They grouped plants or animals with similar-looking features into families. Starting in the 1990s, biologists have extracted DNA and RNA from cells as a guide to how plants or animals should be grouped. Like visual structures, these reveal the underlying design or creation.
The newest book in our Exploring series, Exploring the World of Biology is a fascinating look at life - from the smallest proteins and spores, to the complex life systems of humans and animals.