Dromedary

• 1. Introduction

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  The dromedary, Camelus dromedarius, has not lived wild anywhere on Earth for nearly 2,000 years. The animals alive today are domesticated, or the feral descendants of domesticated ones. Even so, this one-humped camel is a working presence across the dry belts of Africa, the Arabian Peninsula and the Thar desert of Pakistan and India. People first brought it under their care roughly 4,000 years ago, probably in Arabia. How does a large mammal cope when water is days away? Where did it come from, and what kin does it keep? How did a desert animal end up on other continents, and what do people take from it? And what has it passed back to them in return?

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• 2. Desert Engineering

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  An adult male dromedary stands between 1.8 and 2.4 metres at the shoulder, which makes it the tallest of the three camel species. Males weigh from 400 to 690 kilograms. Females are a little smaller, at 1.7 to 1.9 metres tall and 300 to 540 kilograms.

  Every feature of that big frame seems aimed at saving water or shedding heat. Bushy eyebrows and a double row of eyelashes keep sand and glare out of the eyes during windstorms. The camel can also shut its nostrils at will, which helps it hold on to moisture.

  The dromedary lets its body temperature drift between 31 and 41.7 degrees Celsius over the course of a day, so it sweats far less. In temperatures from 30 to 40 degrees Celsius, it needs a drink only every 10 to 15 days. In the hottest weather the interval shrinks to four to seven days. Groups also press against one another to avoid absorbing extra heat from their surroundings.

  The animal can lose more than 30 percent of its water and carry on, which is generally impossible for other mammals. Its red blood cells are oval, a trait found in no other mammal, and this shape eases blood flow during dehydration. Its kidneys are tuned to waste as little water as possible. A network of arteries and veins called the rete mirabile uses countercurrent blood flow to cool the blood heading to the brain.

  When a thirsty camel finally reaches water, it can drink up to 114 litres in one sitting, at 10 to 20 litres every minute.

  The hump, at least 20 centimetres high, is fat held together by fibrous tissue. It can store up to 80 pounds of fat to be broken down when food runs short. Burning that fat makes water evaporate from the lungs, so the net result is a loss of water. A small hump can signal that the animal is starving.

  The feet are flat, leathery pads with two toes each, and like a giraffe, the camel moves both legs on one side together. The pads grip sand and rough ground well but are poorly suited to slippery mud.

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• 3. Herd and Rut

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  A typical dromedary herd numbers about 20 animals: several females led by one dominant male, though females sometimes take turns in front. The group roams and feeds through daylight and rests around noon. When a natural disaster forces a migration, herds can gather into associations of hundreds.

  The males stand or walk between the females and any bachelor males, and sometimes drive the bachelors off. Those bachelors form their own groups or wander alone. In Australia, feral herds cover 50 to 150 square kilometres in the short term, and over a year they may range across several thousand.

  Dromedaries show displeasure by stamping their feet, and they snap at one another without actually biting. They are generally non-aggressive, and females seem to remember the places where they first gave birth or nursed. In the wild, the species has faced wolves, lions and tigers.

  Between January and April, a 1980 study found, high androgen levels turn males difficult to manage. A rutting male vocalizes, throws urine over his back, and blows a soft palate out of his mouth. The palate is called the dulaa in Arabic. It is nearly 18 centimetres long, inflates into a deep pink sac, and is often mistaken for a tongue. Gurgling males cover their mouths in foam.

  Glands on either side of the neck midline secrete a pungent, coffee-coloured fluid during the rut and grow heavier, from 20 to 115 grams. Rival males try to stand taller than each other, lower and bend their heads, and bite at legs. Some try to take an opponent's head between their jaws.

  Mating happens once a year and peaks in the rainy season. The season runs three to five months, or longer in older animals.

  After a gestation of 15 months, a single calf is born, and it moves freely by the end of its first day. Nursing and maternal care last one to two years. Researchers once took two month-old male calves from their mothers and fed them a commercial milk substitute made for lambs. Both grew to normal weights after 30 days.

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• 4. Names and Kin

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  The word dromedary traces back to the Greek dromas, meaning runner, from the phrase dromas kamelos, or running camel. English speakers were using it by the 14th century. The word camel itself reaches English through Latin and Greek from a Semitic source akin to the Hebrew gamal and the Arabic jamal.

  Aristotle, in the fourth century BC, was the first to describe the genus. His History of Animals named two species, a one-humped Arabian camel and a two-humped Bactrian one. Carl Linnaeus gave the dromedary its present binomial name in his 1758 Systema Naturae.

  In 1927, the British veterinarian Arnold Leese sorted dromedaries by habitat. Hill camels were small, muscular pack animals. Larger plains camels split into a desert type, light-burdened and good for riding, and a slow riverine type that carried heavy loads.

  A 2007 study led by Peng Cui of the Chinese Academy of Sciences compared the two tribes of the camel family. Camels form one, and the alpaca, guanaco, llama and vicuña form the other. The tribes diverged 25 million years ago, in the early Miocene, which is earlier than North American fossils had suggested.

  Dromedaries and Bactrian camels breed together and produce fertile offspring. In northern Punjab, Persia and Afghanistan, where their ranges overlap, the two types look less and less different. Hybrids have been bred for about a thousand years, with either one lopsided hump or two humps of unequal size. These hybrids are bigger and stronger than their parents, though some other crosses come out bad-tempered or undersized.

  The fertility of the hybrids led some to propose merging the two species. A 1994 analysis of the mitochondrial cytochrome b gene found a 10.3 percent difference between them.

  The oldest and smallest known camel, Protylopus, lived in North America in the upper Eocene. Later, camels crossed the Bering Strait and spread into Asia, eastern Europe and Africa. The modern dromedary probably arose in the hotter, drier parts of western Asia. A jawbone from 8,200 BC turned up in Saudi Arabia, on the southern coast of the Red Sea.

  In 1975, Richard Bulliet of Columbia University noted a pattern. Dromedaries are abundant where Bactrian camels have vanished, and the reverse is also largely true.

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• 5. Road to Australia

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  In 525 BC, the Persian invasion of Egypt under Cambyses brought domesticated camels into the country. The Persian animals proved poor at trade and travel across the Sahara, and desert crossings were made in chariots pulled by horses. Camels gained popularity after the Islamic conquest of North Africa. The invasion itself was carried out largely on horseback, but new links with the Middle East let camels be imported in great numbers. Strong over long distances and able to carry large cargoes, they made substantial trans-Saharan trade possible for the first time.

  In 1020 AD, dromedaries reached Spain, and Sicily followed in 1059. In 1405, camels were taken to the Canary Islands during European colonisation. They still live there, especially on Lanzarote and in the south of Fuerteventura. Between the 17th and 19th centuries, people tried to establish them in the Caribbean, Colombia, Peru, Bolivia and Brazil. Some arrived in the western United States in the 1850s and in Namibia in the early 1900s. In all those places the animals are now scarce or gone.

  Australia was different. In 1840, about six camels were shipped from Tenerife to Adelaide, and only one survived. That animal, a male named Harry, landed on the 12th of October 1840. His owner was the explorer John Ainsworth Horrocks. Harry was ill-tempered, but he joined an expedition the next year because he could carry heavy loads.

  The next major shipment came in 1860, and between 1860 and 1907 some 10 to 12 thousand camels were imported, mainly for riding and transport. By 2005 the Australian population stood at 500,000, nearly 99 percent of it feral and growing about 10 percent a year. Most live in Western Australia, with smaller numbers in the Northern Territory, Western Queensland and northern South Australia.

  Elsewhere, more than 80 percent of the world's dromedaries live in Africa. The Horn of Africa holds nearly 35 percent, mostly in Somalia, followed by Sudan, Eritrea and Ethiopia. In Asia, nearly 70 percent of the population is in India and Pakistan, and India's largest share, 0.67 million, is in Rajasthan. Pakistan's herds fell from 1.1 million in 1994 to 0.8 million in 2005, a 29 percent decline. Around the Persian Gulf, breeds are named by coat colour, including Al-Majahem, Al-Hamrah, Al-Safrah, Al-Zarkah and Al-Shakha.

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• 6. Riders and Haulers

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  Records from the time of Alexander the Great suggest that dromedaries could cover up to 50 miles a day for a week. They could also go as long as a month without water. The animal has served in warfare since the 6th century BC, prized for outrunning horses in the desert. According to an account by Aurelian, Queen Zenobia used a dromedary to outrun her pursuers on her escape to the Euphrates after her defeat at Palmyra.

  Racing remains popular, especially in the Arab world. Riding camels are known locally as the Dilool in Arabia, the Hageen in Egypt and the Mehara in the Sahara. Several breeds sit within each group. Others include the camels of the Bejas of Sudan and the Anafi camel bred in Sudan.

  Leese described four gaits. The walk is about 4 kilometres an hour. The jog, the most common pace, is nearly 8 to 12 kilometres an hour on level ground. A fast run reaches 14 to 19. The canter, a kind of gallop, can exhaust both camel and rider, so it is kept for short bursts such as races.

  Training for riding ideally begins at three years of age, though the young camel can be stubborn and unruly. Trainers first control the head, then teach sitting and standing commands and acceptance of a rider. A camel at this stage often tries to escape when someone tries to mount. Reins come next. A rider should never strike the neck, but instead strike behind the right leg. Leese described two saddles, the Arabian markloofa for a single rider and the Indian pakra for two.

  A baggage camel should be robust and heavy, with a deep chest and a well-developed hump with room behind it for the saddle. Training for baggage work can start at five years, but no heavy load should be carried before six. The hawia is a typical baggage saddle from Sudan.

  For Bedouin tribes of northern Arabia such as the Ruwallah, the Rashaida, the Bani Sakhr and the Mutayr, one animal supplies transport, milk, meat, wool and leather. Draught camels plough, work oil mills and pull carts, sometimes alongside buffaloes or bullocks. A ploughing camel moves at around 2.5 kilometres an hour. It should work no more than six hours a day, split into four in the morning and two in the afternoon.

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• 7. Milk, Meat and Hair

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  Camel milk is a staple for nomadic desert tribes. It contains 3 percent protein, 3.6 percent fat and 4.4 percent lactose. Compared with cow milk, it holds more sodium, potassium, zinc, iron, copper, manganese, niacin and vitamin C. It holds less thiamin, riboflavin, vitamin B12 and vitamin A.

  Daily yields range from 3.5 to 35 kilograms, and at peak lactation a healthy female typically gives about 9 kilograms. Dromedaries in Somalia may be milked two to four times a day. In Afar, Ethiopia, the milking can happen as often as seven times a day.

  Butter from the milk is difficult to make, but nomads produce small amounts. Cheese is possible too, and a special factory in Nouakchott pasteurises camel milk and makes cheese. In Ethiopia, some people use the milk as an aphrodisiac. Camel milk and camel urine are also used as medicine.

  The meat of a five-year-old dromedary is 76 percent water and 22 percent protein, and its taste and texture resemble beef. Iranian dromedaries have high glycogen levels in their meat, which makes it taste sweet like horse meat. A five-year-old carcass weighs 141 to 310 kilograms, and about 57 percent of it is muscle. The meat is made into burgers, patties, sausages and shawarma. Slaughter is harder than for other livestock because of the animal's size. Most are slaughtered between four and ten years of age, because older animals have tougher, poorer meat. Among African camel herders, camel meat is eaten only in severe food scarcity or for rituals.

  Camel hair is light and conducts heat poorly, so it suits warm clothes, blankets, tents and rugs. The best hair comes from juvenile or feral camels. In India, spring clipping yields 1 to 1.5 kilograms, and in colder regions a single clipping can produce as much as 5.4 kilograms. A dromedary gives about 1 kilogram of wool a year, while a Bactrian camel produces nearly 5 to 12. Camel hides are usually of inferior quality and are less favoured for leather.

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• 8. Illness and Spillover

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  In 2013, a study in Egypt first suggested that the dromedary might host the Middle East respiratory syndrome coronavirus, known as MERS-CoV. A 2013-14 study in Saudi Arabia pointed the same way. The virus there showed unusual genetic stability, and its genome from dromedaries matched human clade B MERS-CoV at 99.9 percent. Another Saudi study found the virus in 90 percent of the camels it tested and suggested camels could be the animal source.

  Overall, the dromedary suffers fewer diseases than goats or cattle. One serious exception is trypanosomiasis, spread by the tsetse fly through a parasite. It brings recurring fever, anaemia and weakness, and it is typically fatal. Brucellosis is another prominent illness. Seroprevalence was low, 2 to 5 percent, among nomadic or moderately free animals, but 8 to 15 percent in denser populations.

  A 2000 study in Jordan found that 83 percent of 32 camels tested positive for sarcoptic mange. In an Egyptian study, the tick Hyalomma dromedarii made up 95.6 percent of the adult ticks taken from camels. This tick is well adapted to arid conditions and can complete much of its life cycle on a single host when stressed. Larvae of the camel nasal fly, Cephalopsis titillator, can cause possibly fatal brain compression.

  In 2005, a joint report from the Saudi Arabian Ministry of Health and the United States Centers for Disease Control and Prevention described five human cases of bubonic plague. All five patients had eaten raw camel liver. Four had severe pharyngitis. Yersinia pestis was isolated from the camel's bone marrow, and also from a jird and from fleas caught at the camel's corral.

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