I watched a re-run on PBS about dogs. I could watch dogs on my TV for hours. What a joy they are. Here's what the show was about:
15 thousand years ago in East Asia wolves TURNED THEMSELVES in dogs, and quickly. Here's the theory: When humans started the first settlements the wolves that were less skittish stayed the closest to the dumps and these more docile wolves bred with each other to become dogs. (The exact same thing happened with wild foxes in the 50s in Russia when they were bred to be better captives, for the fur trade - the Russians quickly ended up with tame foxes that physically changed, and acted like dogs).
Dogs allowed a brand new human activity to occur. Herding. Herd dogs do what people can't. Not only are people not good at running around like that, and fighting off predators, but people can't get the sheep down off of steep hillsides (not even today, still).
Dogs became required for hunting, guarded against attack, guarded goods, kept vermin away, and could sense other dangers for humans that humans couldn't do for themselves (our senses are dreadfully dim compared to a dog's).
Civilization had progressed from there, and dogs have been with us, every step of the way, ever since, doing all sorts of vital things for us.
Without dogs, we would certainly still be clumsy and slow hunter/gatherers.