The Genera
Australopiths, 4.2 to 1.2 mya
The term Australopiths is used to refer to two contemporary and related, but separate genera of human ancesors: Australopithecus and Paranthropus. Their diversity and wide geographical distribution — across the entire African continent — allowed them to exist for 3 million years, about a million years longer than our genus, Homo, has existed.
Homo, 2.2 mya to present
What it was that gave Homo their bigger brains to set them apart from Australopiths isn’t certain, but one theory posits that it was due to a rapid 1000-year cycling of wet and arid conditions, forcing our ancestors to adapt quickly or die.
