Dog's are man's best friend , but primitive humans, particularly females, often used dogs as guards, 800 years ago. But there was an issue with the prehistoric dogs the alpha cavewomen used. These dogs were dubbed ''Dire Wolves'' and lived 800 years ago, but carried parasites such as cysts (sy-sits) and are a reason the caveman and cavewoman ( more specifically called Neanderthals) were extinct. The cave people used them as guards and fed them leftover meat from a mammoth hunt or something. More in-depth on these dogs, they lived 800 years ago and were fierce hunters , more technically wolves, and fossil record shows them working with ancient women, they have about 2 inch fangs and are about 6 feet tall. So even though parasitic, these wolves show that keeping dogs as pets has been a tradition since humans started existing.