Genetic drift happens when chance events cause alleles to spike or decline from one generation to the next. Sometimes a segment of a population gets isolated and continues to grow and mutate on it's own. Sometimes populations change as a result of natural disasters or human intervention. https://youtu.be/mFvmY9JASO4 | CrashCourse

For most of history, human progress was slow and life was more or less the same from generation to generation. But over the last thousand years, we’ve seen giant shifts in basically everything! Study Hall’s new Modern World History series will explore the catalyst events, from imperialism to iPhones, that led to the global society we are today. New episodes every Thursday on the @GoStudyHall channel! | CrashCourse