Who were the first humans? Scientists agree that our early ancestors, Homo erectus, first appeared in Africa 1–2 million years ago. They spread throughout the world and evolved into ancient humans. Most believe that modern humans evolved in Africa, and gradually replaced all the other ancient humans (the 'Out-of-Africa' theory). Some scientists believe that ancient humans may have evolved into modern humans all over the world at around the same time (the 'multiregional' theory). Either way, by about 30,000 years ago, we – Homo sapiens – were the only humans left on the planet.