Camels are even-toed ungulates within the genus Camelus, bearing distinctive fat deposits known as humps on their backs. There are two species: the dromedary or Arabian camel has a single hump, and the Bactrian camel has two humps. They are native to the dry desert areas of West, Central and East Asia, respectively. Both species are domesticated to provide milk and meat, and as beasts of burden.

The term camel is also used more broadly to describe any of the six camel like creatures in the family Camelidae: the two true camels, and the four South American camelids, the llama, alpaca, guanaco, and vicuña.

The average life expectancy of a camel is 40 to 50 years. A fully grown adult camel stands at the shoulder and at the hump. The hump rises about out of its body. Camels can run at up to in short bursts and sustain speeds of up to .

Fossil evidence indicates that the ancestors of modern camels evolved in North America during the Palaeogene period, and later spread to most parts of Asia. Humans first domesticated camels before 2000 BC.

Distribution and numbers

The almost 14 million dromedaries alive today are domesticated animals (mostly living in Somalia, the Sahel, Maghreb, Middle East and Indian subcontinent). An estimated quarter of the world's camel population is found in Somalia and in the Somali Region of Ethiopia, where the camel is an important part of nomadic Somali life. They provide the Somali people with milk, food and transportation. The Bactrian camel is now reduced to an estimated 1.4 million animals, mostly domesticated. It is thought that there are about 1000 wild Bactrian camels in the Gobi Desert in China and Mongolia.

There is a substantial feral population of dromedaries estimated at up to 1,000,000 in central parts of Australia, descended from individuals introduced as transport animals in the 19th century and early 20th century. This population is growing at approximately 18% per year. The government of South Australia has decided to cull the animals using aerial marksmen, because the camels use too much of the limited resources needed by sheep farmers. For more information, see Australian feral camel.

A small population of introduced camels, dromedaries and Bactrians survived in the Southwest United States until the 1900s. These animals, imported from Turkey, were part of the U.S. Camel Corps experiment and used as draft animals in mines and escaped or were released after the project was terminated. A descendant of one of these was seen by a backpacker in Los Padres National Forest in 1972. Twenty-three Bactrian camels were brought to Canada during the Cariboo Gold Rush.

Eco-behavioural adaptations

Camels do not store water in their humps as is commonly believed. The humps are actually a reservoir of fatty tissue. Concentrating body fat in their humps minimizes heat-trapping insulation throughout the rest of their body, which may be an adaptation to living in hot climates. When this tissue is metabolized, it acts as a source of energy, and yields more than 1 g of water for each 1 g of fat converted through reaction with oxygen from air. This process of fat metabolization generates a net loss of water through respiration for the oxygen required to convert the fat. Their ability to withstand long periods without water is due to a series of physiological adaptations. Their red blood cells have an oval shape, unlike those of other mammals, which are circular. This is to facilitate their flow in a dehydrated state. These cells are also more stable in order to withstand high osmotic variation without rupturing when drinking large amounts of water ( to in one drink). Oval red corpuscles are not found in any other mammal, but are present in reptiles, birds, and fish.

Camels are able to withstand changes in body temperature and water content that would kill most other animals. Their temperature ranges from at night up to during the day, and only above this threshold will they begin to sweat. The upper body temperature range is often not reached during the day in milder climatic conditions, and therefore, the camel may not sweat at all during the day. Evaporation of their sweat takes place at the skin level, not at the surface of their coat, thereby being very efficient at cooling the body compared to the amount of water lost through sweating.

A feature of their nostrils is that a large amount of water vapor in their exhalations is trapped and returned to their body fluids, thereby reducing the amount of water lost through respiration.

They can withstand at least 20-25% weight loss due to sweating (most mammals can only withstand about 15% dehydration before cardiac failure results from circulatory disturbance). A camel's blood remains hydrated, even though the body fluids are lost, until this 25% limit is reached.

Camels eating green herbage can ingest sufficient moisture in milder conditions to maintain their bodies' hydrated state without the need for drinking.

A camel's thick coat reflects sunlight, and also insulates it from the intense heat radiated from desert sand. A shorn camel has to sweat 50% more to avoid overheating. Their long legs help by keeping them further from the hot ground. Camels have been known to swim.

Their mouth is very sturdy, able to chew thorny desert plants. Long eyelashes and ear hairs, together with sealable nostrils, form a barrier against sand. Their gait and their widened feet help them move without sinking into the sand.

The kidneys and intestines of a camel are very efficient at retaining water. Urine comes out as a thick syrup, and their feces are so dry that they can fuel fires.

All camelids have an unusual immune system. In all mammals, the Y-shaped antibody molecules consist of two heavy (or long) chains along the length of the Y, and two light (or short) chains at each tip of the Y. Camels also have antibody molecules that have only two heavy chains, which makes them smaller and more durable. These heavy chain-only antibodies, which were discovered in 1993, probably developed 50 million years ago, after camelids split from ruminants and pigs, according to biochemist Serge Muyldermans.

The camel is the only animal to have replaced the wheel (mainly in North Africa) where the wheel had already been established. The camel did not lose that distinction until the wheel was combined with the internal combustion engine in the 20th century.

Military uses

Attempts have been made to employ camels as cavalry and dragoon mounts and as freight animals instead of horses and mules. In some places, such as Australia, some of the camels have become feral and are considered to be dangerous to travelers on camels. The camels were mostly used in combat because of their ability to scare off horses in close ranges, a quality famously employed by the Achaemenid Persians when fighting Lydia, although the Persians usually used camels as baggage trains for arrows and equipment. The horses detest the smell of camels , and therefore, the horses in the vicinity become harder to control. The United States Army had an active camel corps stationed in California in the 19th century, and the brick stables may still be seen at the Benicia Arsenal in Benicia, California, now converted to artists' and artisans' studio spaces. Camels have been used in wars throughout Africa, and also in the East Roman Empire as auxiliary forces known as Dromedarii recruited in desert provinces. During the American Civil War, camels were used at an experimental stage, but were not used any further, as they were unpopular with the men.

Cuisine

Dairy

Camel milk is a staple food of desert nomad tribes and is richer in fat and protein than cow milk. It is said to have many healthful properties. It is used as a medicinal product in India and as an aphrodisiac in Ethiopia. Bedouins believe that the curative powers of camel milk is enhanced if the camel's diet consists of certain plants. Camel milk can readily be made into yogurt, but can only be made into butter or cheese with difficulty. Butter or yogurt made from camel milk is said to have a very faint greenish tinge.

Camel milk cannot be made into butter by the traditional churning method. It can be made if it is soured first, churned, and a clarifying agent added, or if it is churned at , but times vary greatly in achieving results. Until recently, camel milk could not be made into cheese because rennet was unable to coagulate the milk proteins to allow the collection of curds. Under the commission of the FAO, Professor J.P. Ramet of the École Nationale Supérieure d'Agronomie et des Industries Alimentaires (ENSAIA) was able to produce curdling by the addition of calcium phosphate and vegetable rennet. The cheese produced from this process has low levels of cholesterol and lactose. The sale of camel cheese is limited owing to the low yield of cheese from milk and the uncertainty of pasteurization levels for camel milk which makes adherence to dairy import regulations difficult.

Meat

A camel carcass can provide a substantial amount of meat. The male dromedary carcass can weigh or more, while the carcass of a male Bactrian can weigh up to . The carcass of a female camel (or she-camel) weighs less than the male, ranging between , but can provide a substantial amount of meat. The brisket, ribs and loin are among the preferred parts, but the hump is considered a delicacy and is most favored. It is reported that camel meat tastes like coarse beef, but older camels can prove to be tough and less flavorful.

Camel meat has been eaten for centuries. It has been recorded by ancient Greek writers as an available dish in ancient Persia at banquets, usually roasted whole. The ancient Roman emperor Heliogabalus enjoyed camel's heel. Camel meat is still eaten in certain regions including Somalia, where it is called Hilib geyl, Saudi Arabia, Egypt, Libya, Sudan, Kazakhstan and other arid regions where alternative forms of protein may be limited or where camel meat has had a long cultural history. In the Middle East, camel meat is the rarest and most prized source of pastırma. Not just the meat, but also blood is a consumable item as is the case in northern Kenya, where camel blood is a source of iron, vitamin D, salts and minerals. Camel meat is also occasionally found in Australian cuisine, for example, a camel lasagne is available in Alice Springs.

Health issues

A 2005 report issued jointly by the Saudi Ministry of Health and the United States Center for Disease Control details cases of human bubonic plague resulting from the ingestion of raw camel liver.

Cultural prohibitions on consuming camel products

According to Jewish tradition, camel meat and milk are not kosher. Camels possess only one of the two Kosher criteria; although they chew their cuds, they do not possess cloven hooves. (See: Taboo food and drink)

See also

• Dromedary
• Bactrian camel
• Camel racing
• Camel troops
• Camel wrestling
• Camelops
• Australian feral camel
• Camel farming in Sudan

References

1. —Note that Bulliet has many more references to early use of camels
2. Wild Bactrian Camel, Animal Info
3. Edwards GP, Zeng B, Saalfeld WK, Vaarzon-Morel P and McGregor M (Eds). 2008. Managing the impacts of feral camels in Australia: a new way of doing business. DKCRC Report 47. Desert Knowledge Cooperative Research Centre, Alice Springs. Available at http://www.desertknowledgecrc.com.au/publications/contractresearch.html Retrieved November 25, 2009.
4. What secrets lie within the camel's hump?, Lund University, Sweden. Retrieved 7 January 2008.
5. Dromedary, Hannover Zoo. Retrieved 8 January 2008.
6. Examining your blood under a compound microscope, Kidsmicroscope.com. Accessed June 7, 2009.
7. FAO Camels, Camel information from The Food and Agriculture Organization of the U.N.
8. The Straight Dope, Answering the question Is the Camel the Only Animal that can't Swim?
9. Fresh from your local drome'dairy'? Food and Agriculture Organization, July 6, 2001

• Camels and Camel Milk. Report Issued by FAO, United Nations. (1982)
• The Technology of Making Cheese from Camel Milk (Camelus dromedarius) Animal Production and Health Paper Issued by FAO, United Nations. (2001)

External links

• Use of camels by South African police
• National Camel Research Centre, Bikaner (Rajasthan), India
• Camels: God's gift to the Bedouin
• Livius.org: Camels and dromedaries