For reasons both practical and whimsical, man's best friend has been artificially evolved into the most diverse animal on the planet -- a staggering achievement, given that most of the 350 to 400 dog breeds in existence have been around for only a couple hundred years.
The breeders fast-forwarded the normal pace of evolution by combining traits from disparate dogs and accentuating them by breeding those offspring with the largest hints of the desired attributes.
To create a dog well suited for cornering badgers, for instance, it is thought that German hunters in the 18th and 19th centuries brought together some combination of hounds—the basset, a native of France, being the likely suspect -- and terriers, producing a new variation on the theme of dog with stubby legs and a rounded body that enabled it to chase its prey into the mouth of a burrow: hence the dachshund, or "badger dog" in German. (A rival, flimsier history of the breed has it dating back, in some form, to ancient Egypt.)
Pliable skin served as a defense mechanism, allowing the dog to endure sharp-toothed bites without significant damage. A long and sturdy tail helped hunters to retrieve it from an animal's lair, badger in its mouth.
All of the dogs below are from the 2011 Westminster Dog Show. For several of the dogs, the American Kennel Club 2010 popularity ranking is listed after the name of the breed. Images and captions courtesy of Robert Clark and National Geographic. All images are from the February 2012 issue of National Geographic magazine.