A human living in Africa 50,000 years ago wouldn't look out of place groomed and dressed up in a business suit, sipping coffee at a Starbucks in Manhattan. Yet while fully modern humans evolved in Southern Africa, a glance around a Manhattan Starbucks is enough to show you that human evolution has continued since we migrated out of Africa and settled the rest of the world: our stature, skin color, hair, eye color, and other facial features clearly show where in the world at least some of our ancestors lived. Modern humans began branching out into the Near East, Asia, Europe, and Australia by about 40,000 years ago, finally arriving in South America by 12,000 years ago. As our species colonized new environments around the world, we confronted new foods, new pathogens, and other new challenges posed by differences in sunlight, temperature, and altitude. Different populations around the world evolved in response to their unique environmental challenges; as a result, we differ from each other not only in our outward appearance, but also in the inner workings of our bodies. The effects of different evolved adaptations among humans in different parts of world can be seen today in the strong influence our ancestry can have on our health.
To get a better understanding of the changes in our recent evolutionary past, scientists have been looking under the hood at the genetic workings of those evolutionary changes. They're using large genetic inventories of different world populations, such as the Human Genome Diversity Project, to look for mutations that show signs of being actively promoted by evolution.