It's a simple question, but not so simple an answer to explain especially to young children. Charles Darwin's theory of common descent no longer needs to be a scientific mystery to inquisitive young readers. Meet Grandmother Fish. Told in an engaging call and response text where a child can wiggle like a fish or hoot like an ape and brought to life by vibrant artwork, Grandmother Fish takes children and adults through the history of life on our planet and explains how we are all connected. The book also includes comprehensive backmatter, including: An elaborate illustration of the evolutionary tree of life. Helpful science notes for parents. How to explain natural selection to a child.