Breeding began when dogs and humans began to live together. To answer the question “How did breeding start?” you have to differentiate between simply breeding more dogs and selectively breeding for particular traits.
The first humans knew nothing about genetics, but they were observers. It was easy enough to find out when one dog performed better than another while hunting. This dog could have received additional food, which allowed him to pass his genes on to the next generation. This was accidental selective breeding at its finest. The dogs that complemented that first way of life survived and thrived.
This early reproduction was important in the development of the domesticated dog. Survivors learned to seek out people for food, safety, and affection. A dog will observe a person to find out what to do, while a wolf will try to figure things out on his own. This is not something a dog learns, but simply something it does.
As the lives of humans changed, so did the dogs. Farmers, shepherds, and hunters needed specific qualities in the dogs they used to perform their tasks. A hunting dog is not a good substitute for a sheepdog. At this stage, there were basic types of dogs, but no specific breeds. Appearance was also of little importance. As long as the dog was good at its task, it was used to make more puppies that would be just as good, and maybe even better, than their parents.
The oldest known breeds were all utility dogs, such as hunting, herding, and pack dogs. Over time, they began to develop similar appearances and behaviors and the dog breed was born.
The Victorian era was a period of creativity. This included the breeding of dogs. Most modern breeds developed during this time. It was also then that people became interested in pets. Before this period, people did not have dogs because of their cute and cuddly appearance. Small, fluffy dogs emerged as status symbols. Think of Victorians as the first bag dog breeders and you have a modern bond with an old fashion.
The breeding still continues today and has created controversy in some cases. For example, breeding pit bulls to become more vicious has many of this breed banned in cities around the world. Also, some people are not happy with raising exotic puppies like the labradoodle. I would expect this form of reproduction to go on for quite some time.
Today, most dogs are pets. There are still working dogs, but most dogs are companions of people. They are versatile enough to carve a niche for themselves in the lives of human beings regardless of society and the time period in which they live.