Happiness is a dog, because most people who belong to dogs shoot bitter first and then sweet, and their fortune is auspicious, happy and prosperous. Dogs belong to Chordata, Vertebrate, Mammalia, Orthoptera, Carnivora, Schipoda and Canidae. Dogs, also called dogs in Chinese, are distributed all over the world. Dogs, horses, cows, sheep, pigs and chickens are also called six animals.

Dogs are domesticated by wolves. As early as the era of hunting and gathering, people have domesticated dogs as hunting assistants. So dogs are the earliest domesticated domestic animals. Dog bones have been found in Cishan, Wu 'an, Hebei, Peiligang, Xinzheng, Henan, Hemudu, Yuyao, Zhejiang, which proves that it has a long history of domestication. The dog shape unearthed from Sanlihe River in Jiaoxian County, Shandong Province is lifelike, which makes us see the morphological characteristics of domestic dogs in Neolithic Age.

The dog bones unearthed from Anbanpo site in Xi 'an, Shaanxi, have small skulls, protruding frontal bones, small cracked teeth and curved horizontal edge of mandible, which is quite different from that of North China wolves, indicating that the history of human domestication of dogs is indeed very early.