How large are the DNA differences between different breeds of dogs?

In an issue of the journal Science, researchers wrote that the genetic differences between different breeds of dogs are unusually pronounced, so much so that they can determine a dog's breed based solely on its DNA. This phenomenon is related to humans controlling inbreeding in dogs over the past 300 years to obtain different dog characteristics. This shows that humans can indeed play an important role in the field of species evolution.

When researchers analyzed the DNA genetic code of dogs in an attempt to further understand the genetic factors of human diseases, they were surprised to find that, in just the past few hundred years, the genetic differences between different breeds of dogs have reached 30%. This is far greater than the differences between different human races.

Many dogs can be divided by genetic characteristics into 4 major categories and 85 breeds. These include: ancient breeds such as the Eskimo dog and the Pekingese, which may be the breeds closest to their wolf ancestors; hunting dogs such as the Labrador; mastiff-type dogs such as the Rottweiler; and herding dogs, guard dogs and other pastoral dogs.

The researchers said that most breeds bear traces of human artificial creation. Although all dogs belong to one species, different breeds of dogs nonetheless differ enormously in appearance and behavioral habits: for example, weight, size, head shape, fur, ear shape, behavior and diseases. Such numerous small differences existing among different breeds within a single species do not exist in other species. In fact, there are more than 400 breeds of dogs in the world in total, and each one is an independent breeding population.

Over the past 300 years, humans have concentrated and systematically made dogs inbreed to obtain the traits they wanted. Producing such a large number of small genetic differences in such a short time is entirely the result of human action.