What is the history of the dog? How has the modern dog evolved?
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The dog originated about 12,000 to 14,000 years ago in Europe and Asia and was domesticated about
10,000 years ago. Many of our modern dogs probably descended directly from the wolf. These animals
roamed in packs and probably gradually found their way into human encampments. Humans found that
they could depend on the dog to warn of danger, and the dog depended more on humans for food and
shelter. Modern dogs evolved as a result of selective breeding for specific purposes and as a result of the
environment in which they lived.
The ancestor of the entire dog family is believed to have been a civet-like animal, Miacis, that lived 40 or
50 million years ago. Miacis was a small animal with an elongated body and was probably arboreal, or at least
seemed to have spent considerable time in the lush forests of its era. Next was the appearance, about 35 million
years ago, of two apparently direct descendants of Miacis. These were Daphaenus, a large, heavy-boned animal
with a long tail, and Hesperocyon, a small, slender animal that was the forerunner of the long-bodied, coyotelike
"bear dogs" that eventually evolved into modern bears. Hesperocyon can be considered the "grandfather"
of the dog family. Hesperocyon retained the long body and short legs of the primitive carnivores, but unlike
Miacis, Hesperocyon spent little of its time in the trees and began to hunt on the ground. Its claws were
retractile, enabling it to walk on the ground and climb trees.
From Hesperocyon there evolved two distinct dog types. The first, Temnocyon, was an important link in
the evolutionary chain that led to the modern hunting dog of Africa, the Cape hunting dog. The second,
Cynodesmus, is regarded as the ancestor of a large and diversified group of dogs that includes the modern
Eurasian wolf and the American dogs, foxes, and wolves.
The animal considered to be the "father" of modern dogs, Tomarctus, was directly descended from
Hesperocyon. Tomarctus had a body built for speed and endurance as well as for leaping, and differed little in
appearance from the modern dog. This was a hunter, an animal geared for the chase, that brought down prey
by way of slashing teeth. The modern dog still retains much of Tomarctus's anatomical structure and is surpassed
in speed only by the cheetah.
As the evolutionary progress of the Canidae family continued, the progeny of Tomarctus developed into
the modern dogs, wolves, fox, coyotes, fennecs, and jackals. At the same time, descendants of Temnocyon
gradually emerged as the Cape hunting dog of today.
Descending in a direct line from Tomarctus are four major lines of dogs: the herd dogs, the hounds and
terriers, the Northern and toy dogs, and the guard dogs. It is from these four lines, or groups, that modern
dogs are descended. Today, there are seven major groups and more than 400 breeds that have been developed
in the past 100 to 250 years.
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