Usefulness of animals and human affairs
As food
The human population exploits a large number of animal species for food, both of domesticated livestock species in animal husbandry and, mainly at sea, by hunting wild species. Marine fish of many species, such as herring, cod, tuna, mackerel and anchovy, are caught commercially, forming an important part of the diet, including protein and fatty acids, of much of the world’s population. A smaller number of species are farmed commercially, including salmon and carp.
Invertebrates including cephalopods like squid and octopus; crustaceans such as prawns, crabs, and lobsters; and bivalve or gastropod molluscs such as clams, oysters, cockles, and whelks are all hunted or farmed for food. Mammals form a large part of the livestock raised for meat across the world. They include (2011) around 1.4 billion cattle, 1.2 billion sheep, 1 billion domestic pigs, and (1985) over 700 million rabbits.
For clothing and textiles
Textiles from the most utilitarian to the most luxurious are made from animal fibres such as wool, camel hair, angora, cashmere, and mohair. Hunter-gatherers have used animal sinews as lashings and bindings. Leather from cattle, pigs and other species is widely used to make shoes, handbags, belts and many other items. Animals have been hunted and farmed for their fur, to make items such as coats and hats, again ranging from simply warm and practical to the most elegant and expensive.
Dyestuffs including carmine (cochineal), shellac, and kermes have been made from the bodies of insects. In classical times, Tyrian purple was extracted from sea snails such as Stramonita haemastoma (Muricidae) for the clothing of royalty, as recorded by Aristotle and Pliny the Elder.
For work and transport
Working domestic animals including cattle, horses, yaks, camels, and elephants have been used for work and transport from the origins of agriculture, their numbers declining with the arrival of mechanised transport and agricultural machinery. In 2004 they still provided some 80% of the power for the mainly small farms in the third world, and some 20% of the world’s transport, again mainly in rural areas. In mountainous regions unsuitable for wheeled vehicles, pack animals continue to transport goods.
In science
Animals such as the fruit fly Drosophila melanogaster, the zebrafish, the chicken and the house mouse, serve a major role in science as experimental models, both in fundamental biological research, such as in genetics, and in the development of new medicines, which must be tested exhaustively to demonstrate their safety. Millions of mammals, especially mice and rats, are used in experiments each year. A knockout mouse is a genetically modified mouse with an inactivated gene, replaced or disrupted with an artificial piece of DNA. They enable the study of sequenced genes whose functions are unknown.
In medicine
Vaccines have been made using animals since their discovery by Edward Jenner in the 18th century. He noted that inoculation with live cowpox afforded protection against the more dangerous smallpox. In the 19th century, Louis Pasteur developed an attenuated (weakened) vaccine for rabies. In the 20th century, vaccines for the viral diseases mumps and polio were developed using animal cells grown in vitro. An increasing variety of drugs are based on toxins and other molecules of animal origin. The cancer drug Yondelis was isolated from the tunicate Ecteinascidia turbinata. One of dozens of toxins made by the deadly cone snail Conus geographus is used as Prialt in pain relief.
In hunting
Animals, and products made from them, are used to assist in hunting. People have used hunting dogs to help chase down animals such as deer, wolves, and foxes; birds of prey from eagles to small falcons are used in falconry, hunting birds or mammals; and tethered cormorants have been used to catch fish. Dendrobatid poison dart frogs, especially those in the genus Phyllobates, secrete toxins such as Pumiliotoxin 251D and Allopumiliotoxin 267A powerful enough to be used to poison the tips of blowpipe darts.
As pets
A wide variety of animals are kept as pets, from invertebrates such as tarantulas and octopuses, insects including praying mantises, reptiles such as snakes and chameleons, and birds including canaries, parakeets and parrots all finding a place. Anthropomorphism is the innate tendency to attribute human traits, emotions, and intentions to animals, and it is an important aspect of the way that people relate to animals such as pets. However, mammals are the most popular pets in the Western world, with the most kept species being dogs, cats, and rabbits. For example, in America in 2012 there were some 78 million dogs, 86 million cats, and 3.5 million rabbits. There is a tension between the role of animals as companions to humans, and their existence as individuals with rights of their own.
For sport
A wide variety of both terrestrial and aquatic animals are hunted for sport. The aquatic animals most often hunted for sport are fish, including many species from large marine predators such as sharks and tuna, to freshwater fish such as trout and carp. Birds such as partridges, pheasants and ducks, and mammals such as deer and wild boar, are among the terrestrial game animals most often hunted for sport and for food.
In literature and film
Animals as varied as bees, beetles, mice, foxes, crocodiles and elephants play a wide variety of roles in literature and film, from Aesop’s Fables of the classical era to Rudyard Kipling’s Just So Stories and Beatrix Potter’s “little books” starting with the 1901 Tale of Peter Rabbit. A genre of films has been based on oversized insects, including the pioneering 1954 Them!, featuring giant ants mutated by radiation, and the 1957 The Deadly Mantis. Birds have occasionally featured in film, as in Alfred Hitchcock’s 1963 The Birds, loosely based on Daphne du Maurier’s story of the same name, which tells the tale of sudden attacks on people by violent flocks of birds. Ken Loach’s admired 1969 Kes, based on Barry Hines’s 1968 novel A Kestrel for a Knave, tells a story of a boy coming of age by training a kestrel.