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