I was thinking about the Australian Aborigines as I typed my post. I don’t recall how they were categorized in my anthropology course, but I don’t think they were considered a fourth race. I remember several theories about their pattern of migration to Australia. Here is an interesting sentence or two from Wiki:
“In a genetic study in 2011, researchers found evidence, in DNA samples taken from strands of Aboriginal people’s hair, that the ancestors of the Aboriginal population split off from the ancestors of the European and Asian populations between 62,000 and 75,000 years ago—roughly 24,000 years before the European and Asian populations split off from each other.”
Their darker skin could be explained by tens of thousands of years in Australia.
Interesting, thanks for the info.