The dromedary (/ˈdrɒmədɛri/ or /-ədri/), also called the Arabian camel or the Indian camel (Camelus dromedarius), is a large, even-toed ungulate with one hump on its back.First described by Aristotle, the dromedary was given its binomial name by Carl Linnaeus in 1758. The dromedary is the next largest member of the camel family after the Bactrian camel[citation needed]. The oldest known ancestor of the dromedary is the Protylopus. Males are 1.8–2 m (5.9–6.6 ft) tall and females are 1.7–1.9 m (5.6–6.2 ft) tall. Males range from 400–600 kg (880–1,320 lb), while females weigh 300–540 kg (660–1,190 lb). They vary in colour from a light beige to dark brown. The notable hump, measuring 20 cm (7.9 in) high, is composed of fat bound together by fibrous tissue.Their diet includes foliage and desert vegetation, like thorny plants which their extremely tough mouths allow them to eat. These camels are active in the day, and rest together in groups. Led by a dominant male, each herd consists of about 20 individuals. Some males form bachelor groups. Dromedaries show no signs of territoriality, as herds often merge during calamities. Predators in the wild include wolves, lions, and tigers. Dromedaries use a wide set of vocalizations to communicate with each other. They have various adaptations to help them exist in their desert habitat. Dromedaries have bushy eyebrows and two rows of long eyelashes to protect their eyes, and can close their nostrils to face sandstorms. Their ears are also lined with protective hair. When water-deprived, they can fluctuate their body temperature by 6 °C, changing from a morning minimum of 34° to a maximum of 40° or so in the afternoon. This reduces heat flow from the environment to the body and thereby water loss through perspiration is minimised. They have specialized kidneys, which make them able to tolerate water loss of more than 30% of their body mass; a loss of 15% would prove fatal in most other animals. Mating usually occurs in winter, often overlapping the rainy season. One calf is born after the gestational period of 15 months, and is nurtured for about two years.The dromedary's origin is unclear, but it was probably domesticated in Somalia or Arabian Peninsula about 4000 years ago, with a general agreement among experts about the domestication of the one-humped camel. The domesticated form occurs widely in Horn of Africa, North Africa, South Asia, and the Middle East. Today, almost 13 million dromedaries are domesticated. They are beneficial as beasts of burden, and their docility and toughness compared to cattle are additional advantages. The hair is a highly regarded source material for woven goods. Another useful feature is their dung which can be used as fertiliser and fuel.