Known to humans as man’s best friend, dogs have evolved from wild wolves into more than 400 distinct breeds. Through the rudimentary art of genetic selection, people have bred dogs to accentuate instincts that serve distinct societal needs. Domesticated dogs are able to perform a remarkable variety of tasks. Some assist search and rescue teams following natural disasters or reports of missing persons; others sniff out bombs, drugs, and contraband atop Mt. Everest or miles under the sea in a military submarine; and yet others work at customs ports to expose forest insect pests hiding in shipments of wood from abroad.
These four-legged canines, who walk on their toes instead of their heels, are extremely intelligent and quick learners with a superior sense of smell and sight. They are also homeothermic, meaning they regulate their body temperature by adjusting how much or little they sweat. Dogs communicate with their owners via the positioning of their tails, which serves as an emotional meter: A vertical tail signals confidence and trust; a lowered tail suggests fear or submission.
While dogs are held in high esteem in Western society, in some parts of the world they are more often considered beasts of burden or living weapons than friends. In either case, their loyalty and companionship make them a great addition to any story, especially for children.