Origins of Dogs:
Dogs are members of the order Carnivora, a group of mammals
that originated about 55 million years ago. The current members
of Carnivora include animals in the family Canidae.
Wolves, jackals, and our dogs, among others animals, make up the
The first of the Canidae, called Hesperocyon,
lived about 25 to 30 million years ago in North America.
Some Canidae migrated to South America where they evolved
into foxes. Other Canidae gradually evolved into animals
that began the genus Canis. These animals moved
westward over the Bering Strait and continued into Eurasia.
The oldest representative of the Canis is Canis cipio;
it was discovered in Concud, Spain. It lived about 6 million years
ago. The genus continued evolving, producing Canis lupus, or
wolf, about 300,000 years ago. The wolf is widely believed to be the
forerunner of modern day dogs.
Because humans domesticated dogs about 20,000 years ago, we have
no precise knowledge of how this was done. Presumably, young wolves
were caught and raised in captivity. Then, humans would breed those
animals that had the characteristics they wanted to keep. Over many
generations, different types of dogs were developed -- those specialized
for hunting, for guarding, and for sheep herding, among others.
Although most modern dog breeds were developed about 100 years ago
and a few in the 1700s, these general dog classes -- hunters, guard
dogs, and herders, have been known for thousands of years.
Source: The Reader's Digest Illustrated Book of Dogs,
2nd ed., The Reader's Digest Association, Inc., Pleasantville, New York,
1993, pp. 9-10.