If new, separate human species are not found, perhaps they can be argued into existence.
Start by insisting that absolutely everything is a big accident.
Darwinian theory, by its very nature, demands this zealous emphasis on isolated, randomly generated characteristics or events — warring trivia, basically.
The little we know of early religion was not predicted by naturalist theses — and has not confirmed any of them.
Naturalism commands us to believe that mud somehow produced mind. Therefore, our ancestors are not gods or heroes but half human or less.