Elephants in captivity are elephants kept in a confining area, such as a zoo, circus, or camp, where they are fed and cared for by humans and usually exhibited for entertainment or educational purposes. Most captive elephants are taken from the wild, as they breed poorly in captivity. The low rate of captive births cannot balance out captive mortality.Selective breeding of elephants is impractical due to their long reproductive cycle, so there are no domesticated breeds. Most captives are endangered Asian elephants. African bush elephants and African forest elephants are less amenable to training. Animal rights organizations estimate there are 15,000 to 20,000 elephants in captivity worldwide. For comparison, the International Union for Conservation of Nature (IUCN) estimates the total population of Asian elephants in the wild to be 40,000 to 50,000, and that of African elephants in the wild to be 400,000 to 600,000. Elephants in captivity are elephants kept in a confining area, such as a zoo, circus, or camp, where they are fed and cared for by humans and usually exhibited for entertainment or educational purposes. Most captive elephants are taken from the wild, as they breed poorly in captivity. The low rate of captive births cannot balance out captive mortality.Selective breeding of elephants is impractical due to their long reproductive cycle, so there are no domesticated breeds. Most captives are endangered Asian elephants. African bush elephants and African forest elephants are less amenable to training. Animal rights organizations estimate there are 15,000 to 20,000 elephants in captivity worldwide. For comparison, the International Union for Conservation of Nature (IUCN) estimates the total population of Asian elephants in the wild to be 40,000 to 50,000, and that of African elephants in the wild to be 400,000 to 600,000. Tame elephants have been recorded since the Indus Valley civilization around 2,000 BCE. With mahouts, they have been used as working animals in forestry, as war elephants (by commanders such as Hannibal), for cultural and ceremonial use (such as temple elephants), as a method of execution, for public displays such as circus elephants, in elephant polo and in zoological gardens. The expression white elephant derives from a white elephant being considered sacred and therefore disqualified from useful work, yet posing a large ownership cost. The origin of the expression is from the story that the kings of Siam gave white elephants as a gift to courtiers they disliked, in order to ruin the recipient by the great expense incurred in maintaining the animal. Elephants have the largest brains of all land animals, and ever since the time of Ancient Greek philosopher Aristotle, have been renowned for their cognitive skills, with behavioural patterns shared with humans. Pliny the Elder described the animal as being closest to a human in sensibilities. They also have a longer lifespan than most livestock. Elephants exhibit a wide variety of behaviors, including those associated with grief, learning, allomothering, mimicry, play, altruism, use of tools, compassion, cooperation, self-awareness, memory, and language. The adult male elephant occasionally goes through a musth period, making him dangerously aggressive. Successful hand-rearing of orphaned calves depends critically on the milk formula used. Human infant formula is commonly used, but requires to be supplemented with bovine colostrum (commercially available in substitute form), and lactobacillus to protect the gastrointestinal tract. To provide additional fat, desiccated coconut and butterfat are added, with vitamin and mineral supplements, in particular vitamin E, vitamin B, and calcium. Rice water strained from cooked rice and glutinous rice broth are useful and are added to the formula to combat diarrhea. Rice cereal, milled whole barley or oatmeal, desiccated coconut, and other ground solid foods are added to the milk of older calves to ease the transition to solid foods. Professor Niels Bolwig at Ibadan University, Nigeria in 1963 successfully reared an orphaned infant elephant from a few days old by developing his own rich milk formula consisting of cows' milk and butter fat. This is believed to be the first successful rearing. Until then most rearing attempts had been unsuccessful due to diet intolerance. Animal welfare researchers have raised concern about the physical and mental health of elephants in captivity at zoos in the UK and the US. According to a report published by the Center for Disease Control, in North America, approximately 2% of African, and 12% of Asian captive elephants are thought to be infected with tuberculosis. In 2012, two elephants in Tete d’Or Zoo, Lyon (France), were diagnosed with tuberculosis. Due to the threat of transmitting tuberculosis to other animals or visitors to the zoo, their euthanasia was initially ordered by city authorities but a court later overturned this decision.