16 Dogs by Design-High

Dogs by Design FOCUS Question How and why have people created so many dog breeds?

Survival! of the Chosen Genes are a part of every cell in every living thing. They control how living things look and behave. In order to survive, wild animals must adapt to changes in their habitat. The ones that succeed are able to reproduce. Then they pass on their genes to the next generation. This process is known as natural selection, or "survival of the fittest." But sometimes people decide which animals get to pass on their genes. We might want pigs that gain weight faster. We may want chickens that lay more eggs. Over the years, people have bred many kinds of animals to be tame or to serve a special purpose. These are domesticated animals. They are different from wild animals. They are part of an artificial process.

Taming Wolves The dog was the first domesticated animal. About fifteen thousand years ago, humans formed relationships with wolves for the first time. Perhaps people found abandoned wolf pups and raised them. Or maybe tamer wolves spent time near humans, hoping for easy food. People liked wolves that showed certain traits, or qualities. They wanted wolves to help them hunt or protect them from danger. The most important trait people wanted in wolves was tameness. Tamer wolves were friendlier. So people bred the wolves that were the tamest. Over many generations, these tame wolves became what we now call dogs.

Why We Breed Dogs Since the first dogs were designed, people have created more than four hundred dog breeds, or types of dogs. They selected dogs with certain traits and bred them. Those desired traits were passed along to the offspring. Dog breeds come in many shapes and sizes. They also behave in very different ways. But all dog breeds are part of the same species, Canis lupus familiaris. Some breeds are great at hunting. Some breeds herd animals or carry loads. Other breeds are simply our companions. The American Kennel Club divides dog breeds into seven groups— sporting, hound, working, herding, terrier, toy, and non-sporting. One of the tallest dogs ever was a Great Dane named Zeus. He was 112 centimeters (44 in.) tall. The smallest dog alive is a pocket-sized pooch named Miracle Milly. This Chihuahua measures only 9.5 centimeters (3.8 in.) tall. Now, that's small!

Hunting Dogs The sporting and hound groups are considered hunting dogs. Retrievers, setters, spaniels, and pointers are examples of sporting dogs. They were bred to help locate and retrieve game birds, such as pheasants on land or ducks in the water. Hounds were bred to hunt for game on land, such as rabbits, raccoons, or deer. They hunt with their strong sense of sight or scent. This group includes greyhounds, dachshunds, bassets, and beagles.

Working Dogs Three dog groups are considered working dogs. One of the groups is actually called the working dog group. Its members include huskies, Saint Bernards, and Doberman pinschers. They may pull sleds, perform search and rescue operations, or act as guards. Herding dogs such as collies, German shepherds, and English sheepdogs help ranchers or shepherds. These breeds round up livestock, such as sheep or cattle, into pastures or pens. Terriers, including Airedales and Scottish terriers, are bred to control pests. These dogs kill rats and other vermin. The dogs chase the pests or dig them up from underground dens. Wowser! Huskies in the Iditarod race pull a sled for 1,688 kilometers (1,049 mi.) over nine days.