Written in each person’s DNA is an unbroken record of our shared ancestry as human beings—where we arose and how we moved and mingled to create the tapestry of cultures we now see around the world. In Episode I of this three-part series, we will look at our closest living animal relative. Why is it that chimpanzees from different parts of Africa look the same (even to experts), while humans from different parts of the world look different? To help answer this question, we will compare the genetic diversity of humans and chimps to see what it tells us about how the two groups evolved. We will learn practical methods to collect DNA samples and to amplify and sequence a bit of DNA from the cell’s energy factory, the mitochondria. We will introduce bioinformatics tools to compare DNA from different individuals and to make a simple tree of their relatedness to each other.