Ok, I am not supporting bestiality here. But, I just came to know about a Dogxim, a dog fox hybrid and I had known for a long time that horses and donkeys can breed (to produce a mule). So, I was just curious, can humans breed with any other animals closely related to us?
We’re talking way earlier than cavemen. The last interbreeding between our ancestors and chimps’ ancestors happened (using the most recent estimate I could find) a million years before the least recent evidence of the use of any stone tools. This is not a human that would be recognisable at all as a human.