I hope this book has convinced you of five ideas. First, evolution is ubiquitous. Second, people have shaped evolution of populations of human and non-human species. Third, anthropogenic evolution has shaped human as well as natural history. Fourth, human and non-human populations have coevolved, or repeatedly changed in response to each other. And fifth, uniting the insights of history and biology in evolutionary history enables us to understand the past more fully than either discipline does alone.

I like to think that these ideas can help resolve puzzles that we all encounter in our daily lives. Why do our relatives die of infections despite treatment with antibiotics? Why do we catch so many small fish? Why do mounted heads of game animals killed two hundred years ago sport bigger horns than we see today? Why do some of us have light skin and others dark skin? Why do insects in my garden survive insecticides? Why do adults in some countries avoid drinking milk? Why do I wear cotton clothes? Evolution supplies part of the answer to all these questions, and human history supplies another part. We all live in a world shaped by evolutionary history.