A few years back, after a hunter was charged with shooting a polar bear/grizzly bear cross when he only had a grizzly bear hunting licence I started to think that humanoids may not have had an ancestor (or missing link) species in the way that people imagine it. Basically, imagine Africa as a continent being full of pre-human apes that have adapted to their environment as best as they could, and then (for some reason) these species start heavily inter-breeding; being that the mortality rate would be very high for a variety of reasons, the random mixing of traits would result in offspring that were both dramatically more successful and unusually unsuccessful. Within a very short period of time (a couple hundred years) all of the distinctive species could be virtually eliminated in favour of one dominant species.
