20,000 years ago, humans lived everywhere on Aurah. Land bridges allowed them to move virtually anywhere. Then a massive radiation burst from Theta Proxima merged their DNA with the animals they came into contact with, particularly those they ate as food or used for furs and bone tools.
At first the human reaction was hostile. Tribes either slaughtered their altered babies the moment they came into the world, or made them live as outcasts. Yet over three or four generations, with most babies emerging altered and the adults changing too, it was clear anthroes were there to stay.
New anthro clans emerged, orientated mostly by species. The carnivorous ones started hunting both herbivorous anthroes and humans. Faced with increasing persecution, nearly all humans died out. Some retreated far into the wilderness to live on, while a few escaped on simple boats to Brama or to the islands north of Borea. There were some anthroes here, but few enough to avoid.
Humans were nearly extinct by 10,000 years ago, while rising sea levels split up the various anthro clans. Anthroes are gradually rediscovering them and welcoming them back into society. Indeed, in some cultures they were judged to be gods or supreme beings; the fathers of races. However, years of ignorance and the machinations of fanatical groups such as the Brotherhood of the Fur have confounded these efforts.
Humans certainly did not fare well with the rise of anthroes. However, it is said that there were also fish, bird and reptilian races that emerged and fell at the same time. These anthroes were confounded by the problems of reproduction, or with having to adapt to activities their bodies were unsuitable to, such as flying or diving underwater. Whether there are any of these groups still around is not fully known.