Transcript: Similarity or dissimilarity in DNA can be used to trace human origins. The oldest human civilizations date back only ten thousand years, the oldest human artifacts about thirty or forty thousand years. Yet changes in the structure of DNA can be used to trace human origins back hundreds of thousands of years, even millions of years. The first human ancestor dates back to two or three million years ago. By watching the change in DNA as artifacts are found in different parts of the planet, it’s possible to show how human pre-ancestors moved across our planet. The earliest humans lived in Africa. They subsequently migrated to Europe and Asia and then across the land bridge to North and South America. These genetic differences are traced in present day humans. For example, this activity called forming phylogenetic trees can be used to show that racial differences, the superficial differences between people of African, or Asian, or European descent, are utterly trivial when considered in terms of DNA. The typical variation in the DNA between two people, any two people, from one race is as large as the typical differences in DNA between the races. Thus, the races and their differences are truly superficial. At the level of DNA we are all the same.