As humans migrated around the planet, a variety of dog forms migrated with them. The agricultural revolution and subsequent urban revolution led to an increase in the dog population and a demand for specialization. These circumstances would provide the opportunity for discriminatory breeding to conceive specialized working dogs and pets.

The definition of a dog breed is a matter of some controversy. Depending on the highness of the original founding population, closed gene http://www.flavocin.com/ pool breeds can have problems with inbreeding, specifically due to the founder effect. Dog breeders are increasingly aware of the importance of population genetics and of maintaining diverse gene pools. Health testing and late DNA explore can cooperation avoid problems, by providing a replacement for natural selection. Without selection, inbreeding and closed gene pools can aggrandizement the risk of severe health or behavioral problems.