The origin of domestic dogs

There exist two theories, concerning the origin of dogs.

The representatives of the first theory uphold the idea of a single ancestor and explain the diversity of dogs by the impact of culture and climate. At present the wolf is regarded the dogs' ancestor.

The second theory (one of the greatest representatives of which was Charles Darwin) is based on the idea that this diversity can be explained by the existence of various dogs' ancestors. The supporters of the theory give the following arguments:

1. Domestic dogs with clear signs of breed appeared long ago in the areas far from each other;

2. Dogs are similar to canines living in the same areas;

3. Diversity and heterogeneity of the domestic dogs group can not be explained only by artificial selection, made from the descendants of one ancestor.

Thus there are the following facts and hypotheses:

Facts

1. Domestic dogs have a broad range of breeds dissimilar to each other in comparison with other domestic pets.

2. The species composition of wild canine during the period of domestication was much broader than now, though, among the representatives of the blood line living now there are species, "claiming" to the title of the dog's ancestor.

3. In prehistoric times there existed many shaped breeds of dogs.

4. During the period of first civilizations dogs were already well represented by a broad spectrum of highly diverse groups of breeds, which centres of habitation were considerably remote from each other.

5. There are numerous cases of pairing dogs with wolves, coyotes and American red wolves. Pairing with ordinary jackal is also possible.

Hypotheses

1. Most supporters of a single ancestor theory consider the wolf to be the dog's ancestor; they argue that the domestication occurred in one place and then descendants spread across the Earth.

2. All breeds of dogs come from the wolf, but from different subspecies, and domestication took place in different areas separately.

3. Because the participation of the wolf is obvious in many breeds, then, if we assume the presence of another ancestor than the theory of a single ancestor becomes untenable.

5. The theory of various ancestors seems the most probable to the majority of scientists. Interspecific hybridization, combined with artificial selection is also possible.