The domestic dog (Canis lupus familiaris)[2][3] is a subspecies of the gray wolf (Canis lupus), a member of the Canidae family of the mammal...
The domestic dog (Canis lupus familiaris)[2][3] is a subspecies of the gray wolf (Canis lupus), a member of the Canidae family of the mammalian order Carnivora. The term "domestic dog" is generally used for both domesticated and feral varieties. The dog was the first domesticated animal[4] and has been the most widely kept working, hunting, and pet animal in human history. The word "dog" can also refer to the male of a canine species,[5] as opposed to the word "bitch" which refers to the female of the species.nnMtDNA evidence shows an evolutionary split between the modern dog's lineage and the modern wolf's lineage around 100,000 years ago but, as of 2013, the oldest fossil specimens genetically linked to the modern dog's lineage date to approximately 33,000--36,000 years ago.[4][6] Dogs' value to early human hunter-gatherers led to them quickly becoming ubiquitous across world cultures. Dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals. This impact on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogs are also a source of meat.[7][8] In 2001, there were estimated to be 400 million dogs in the world.[9]nnMost breeds of dogs are at most a few hundred years old, having been artificially selected for particular morphologies and behaviors by people for specific functional roles. Through this selective breeding, the dog has developed into hundreds of varied breeds, and shows more behavioral and morphological variation than any other land mammal.[10] For example, height measured to the withers ranges from 15.2 centimetres (6.0 in) in the Chihuahua to about 76 cm (30 in) in the Irish Wolfhound; color varies from white through grays (usually called "blue") to black, and browns from light (tan) to dark ("red" or "chocolate") in a wide variation of patterns; coats can be short or long, coarse-haired to wool-like, straight, curly, or smooth.[11] It is common for most breeds to shed this coat.nThe domestic cat[1][2] (Felis catus[2] or Felis silvestris catus[4]) is a small, usually furry, domesticated, and carnivorous mammal. It is often called the housecat when kept as an indoor pet,[6] or simply the cat when there is no need to distinguish it from other felids and felines. Cats are often valued by humans for companionship and their ability to hunt vermin and household pests.nnCats are similar in anatomy to the other felids, with strong, flexible bodies, quick reflexes, sharp retractable claws, and teeth adapted to killing small prey. Cat senses fit a crepuscular and predatory ecological niche. Cats can hear sounds too faint or too high in frequency for human ears, such as those made by mice and other small game. They can see in near darkness. Like most other mammals, cats have poorer color vision and a better sense of smell than humans.nnDespite being solitary hunters, cats are a social species, and cat communication includes the use of a variety of vocalizations (meowing, purring, trilling, hissing, growling and grunting) as well as cat pheromones and types of cat-specific body language.[7]nnCats have a rapid breeding rate. Under controlled breeding, they can be bred and shown as registered pedigree pets, a hobby known as cat fancy. Failure to control the breeding of pet cats by spaying and neutering, and the abandonment of former household pets, has resulted in large numbers of feral cats worldwide, requiring population control.[8]nnSince cats were cult animals in ancient Egypt, they were commonly believed to have been domesticated there,[9] but there may have been instances of domestication as early as the Neolithic.[10]nnA genetic study in 2007 revealed that domestic cats are descended from African wildcats (Felis silvestris lybica) c. 8000 BCE, in the Middle East.[9][11] According to Scientific American, cats are the most popular pet in the world, and are now found almost every place where people live.[12] Less
