According to science, people of the earth began in Africa, and the more people migrated around the world, the more physical changes would develop because of adaptations to certain areas. People who evolved in the same spot for a long time did not change much.
Having dreadlocks can actually exclude you from certain trials! Occasionally, we need to do an EEG test as part of a trial, which requires you to wear a tight-fitting cap which monitors brain activity. The cap can't go over dreads!