Breeding began when dogs and humans first began cohabitating. To answer the question “How did breeding start?” you have to differentiate between simply breeding for more dogs and selective breeding for particular traits.
Early humans knew nothing about genetics, but they were observant. It was easy enough to figure out when one dog out performed another while hunting. This dog might have received extra food, which enabled it to pass its genes to the next generation. This was accidental selective breeding at its finest. The dogs that complemented that early way of life survived and thrived.
This early breeding was important in developing the domesticated dog. The survivors learned to look to people for food, security and affection. A dog will watch a person to learn what it should do, while a wolf will try to figure things out on its own. This is not something that a dog learns, but instead it is simply something that it does.
As the lives of humans changed so did the dogs. Farmers, shepherds and hunters all needed specific qualities in the dogs that they used to perform tasks. A hunting dog makes a poor substitute for a herding dog. At this stage, there were basic types of dogs, but no specific breeds. Looks was also of little importance. As long as the dog was good at its task, it was used to make more pups that would be as good, and maybe even better, than its parents were.
The oldest known breeds were all utility dogs such as hunting, herding and pack dogs. Over time, they began to develop similar looks and behaviors and the dog breed was born.
The Victorian era was a period of creativity. This included the breeding of dogs. The majority of the modern breeds were developed during this time. This is also when people began to develop an interest in pets. Prior to this period people did not keep dogs around for their cute and cuddly looks. Small, fluffy dogs came about as status symbols. Think of the Victorians as the first breeders of purse dogs and you will have a modern link to an old fad.
Breeding still goes on today and has created controversy in some cases. For instance the breeding of pitbulls to become more vicious has many of this breed being banned from cities throughout the world. Also some people are not happy with the breeding of exotic puppies such as the labradoodle. I would expect that this form of breeding will carry on for quite some time.
Today most dogs are pets. There are still working dogs out there but the majority of dogs are companions to people. They are versatile enough to carve out a niche in the lives of humans regardless of the society and period of time in which they live.