Final answer:
The African Replacement Model, or Out of Africa model, posits that modern humans originated in Africa and then spread out, replacing other human species globally.
Step-by-step explanation:
The African Replacement Model, also known as the Out of Africa model, is a theory that suggests modern humans originated in Africa about 200,000 years ago. According to this model, these early humans then migrated outwards from Africa around 100,000 years ago, leading to the replacement of other human species around the world. This model is the most widely accepted explanation for the origin of modern humans and is supported by various forms of evidence, including genetic data that shows a closer relation of humans outside Africa to those within Africa. The genetic variance found within Africa and not replicated elsewhere supports the idea that Africa is the cradle of human genetic diversity.