How Have Dogs Evolved Over the Years?

The closest relatives of domestic dogs are jackals, coyotes and wolves. Whether or not domestic dogs developed directly from wolves or from a prehistoric subspecies is unknown. What is known is how their relationship with humans has formed. The most likely theory is that wolves began scavenging along human settlements about 100,000 years ago, and began the process that would create the domestic dog.

Contact with human settlements benefited the wolves in natural selection. Those wolves that ventured close to humans were better fed, stronger and were thus able to pass on the genes that initially made them fearless. Essentially they began to domesticate themselves by passing along the genes that made them less wary of human presence. It is also possible that humans raised some wolf cubs and incorporated them into their daily lives.

This eventual relationship between humans and wolves was inevitable. Wolves are social pack animals. As a wolf cub grows it develops attachment behavior and begins to exhibit dominant and submissive postures. The wolves recognized a pack within the structure of human settlements and their social nature allowed them to adapt to belong. Soon these semi-domesticated animals served as guards and hunters and cleaned up the scraps around village sites.

The first domesticated dog is thought to have appeared between 10,000 and 15,000 years ago. Evidence exists that 13,000 years ago dogs crossed the Bering land bridge with a colony of early humans. Cave pictures depict that dogs and people lived together in 7,000 B.C. and the ancient Egyptians kept hunting dogs around 4,500 B.C. The Greeks and Romans began employing dogs both in war and as companions around 300 B.C. Some of today's companion dogs began appearing in 1000 B.C. in Asia. One of the most notable of these is the shih tzu, which was kept by the emperors of China.

Various cultures around the world have viewed dogs differently over the centuries. These views have affected how domesticated dogs have evolved within a community. Islamic cultures labeled the dog as "unclean," therefore seeing the evolution of semi-domesticated animals that live on the fringe of society. The Chinese, however, viewed the dog with respect and admiration. This led to the evolution of some the first dwarf and miniaturized breeds. Dog breed evolution has always been dependent upon the needs of the people in the region.

The start of the 21st century has seen a trend toward purebred breeding. Fewer new breeds are appearing, and more conservation efforts have been exerted for existing breeds. This trend has both its advantages and disadvantages. Purebred breeding leads to a consistent size, shape, color and temperament. It also increases the concentration of unwanted or dangerous genes in a small gene pool.