Survival of the fittest...dogs

I find it interesting that certain dogs seem to have specific abilities hard wired into their brains without any training. For example, some dogs are classified as herding dogs. This means that they tend to run around animals and keep them going in a certain direction. I noticed that my dog does this at the dog park. We never trained her to do it. How did herding become important to survival? Was it simply because people wanted herding dogs, so they only bred herding dogs? That would seem to take a lot longer to make herding a part of a breed than people have been breeding dogs. Did we cause dogs to evolve more quickly than other animals? Or do we even know why things like herding are natural to some dogs?