Elephant
November 20th, 2008
Elephants are the largest land animals. The elephant's gestation period is 22 months, the longest of any land animal. At birth it is common for an elephant calf to weigh 120 kilograms (260 lb). They typically live for 50 to 70 years, but the oldest recorded elephant lived for 82 years. The largest elephant ever recorded was shot in Angola in 1956. This male weighed about 12,000 kilograms (26,000 lb), with a shoulder height of 4.2 metres (14 ft), a metre (yard) taller than the average male African elephant. The smallest elephants, about the size of a calf or a large pig, were a prehistoric species that lived on the island of Crete during the Pleistocene epoch.
The elephant has appeared in cultures across the world. They are a symbol of wisdom in Asian cultures and are famed for their memory and intelligence, where they are thought to be on par with cetaceans and hominids. Aristotle once said the elephant was "the beast which passeth all others in wit and mind". The word "elephant" has its origins in the Greek ἐλέφας, meaning "ivory" or "elephant".
Healthy adult elephants have no natural predators, although lions may take calves or weak individuals. They are, however, increasingly threatened by human intrusion and poaching. Once numbering in the millions, the African elephant population has dwindled to between 470,000 and 690,000 individuals. The elephant is now a protected species worldwide, with restrictions in place on capture, domestic use, and trade in products such as ivory.
The African Elephant genus contains two (or, arguably, three) living species; whereas, the Asian Elephant species is the only surviving member of the Asian Elephant genus, but can be divided into four subspecies.
Although the fossil evidence is uncertain, scientists discovered genetic evidence that the elephant family shares distant ancestry with the sirenians (sea cows) and the hyraxes through gene comparisons. In the distant past, members of the hyrax family grew to large sizes, and it seems likely that the common ancestor of all three modern families was some kind of amphibious hyracoid. One theory suggests that these animals spent most of their time under water, using their trunks like snorkels for breathing. Modern elephants have retained this ability and are known to swim in that manner for up to 6 hours and 50 km (30 miles).
In the past, there was a much wider variety of elephant genera, including the mammoths, stegodons and deinotheria. There was also a much wider variety of species.
With a mass just over 5 kg (11 lb), elephant brains are larger than those of any other land animal, and although the largest whales have body masses twentyfold those of a typical elephant, whale brains are barely twice the mass of an elephant's. A wide variety of behaviours, including those associated with grief, making music, art, altruism, allomothering, play, use of tools, compassion and self-awareness evidence a highly intelligent species on par with cetaceans and primates. The largest areas in the elephant brain are those responsible for hearing, smell and movement coordination.
Elephants have well innervated trunks, and an exceptional sense of hearing and smell. The hearing receptors reside not only in ears, but also in trunks that are sensitive to vibrations, and most significantly feet, which have special receptors for low frequency sound and are exceptionally well innervated. Elephants communicate by sound over large distances of several kilometers partly through the ground, which is important for their social lives. Elephants are observed listening by putting trunks on the ground and carefully positioning their feet.
Elephant's very good at looking at objects with their eyes. Their eyes are aimed down and to look up they have to put their head up very high, and that is a problem for them.
In addition to their bellows, roars and widely recognized trumpet-like calls; elephants communicate over long distances by producing and receiving low-frequency sound (infrasound), a sub-sonic rumbling, which can travel through the ground farther than sound travels through the air. This can be felt by the sensitive skin of an elephant's feet and trunk, which pick up the resonant vibrations much as the flat skin on the head of a drum. To listen attentively, every member of the herd will lift one foreleg from the ground, and face the source of the sound, or often lay its trunk on the ground. The lifting presumably increases the ground contact and sensitivity of the remaining legs. This ability is thought also to aid their navigation by use of external sources of infrasound. Discovery of this new aspect of elephant social communication and perception came with breakthroughs in audio technology, which can pick up frequencies outside the range of the human ear. Pioneering research in elephant infrasound communication was done by Katy Payne, of the Elephant Listening Project, and is detailed in her book Silent Thunder. Though this research is still in its infancy, it is helping to solve many mysteries, such as how elephants can find distant potential mates, and how social groups are able to coordinate their movements over extensive range.
Although successful hybridisation between African and Asian Elephant species is highly unlikely in the wild, in 1978 at Chester Zoo, an Asian elephant cow gave birth to a hybrid calf sired by an African elephant bull (the old terms are used here as these events pre-date the current classifications). "Motty", the resulting hybrid male calf, had an African elephant's cheeks, their ears (large with pointed lobes) and legs (longer and slimmer), but the toenail numbers, (5 for each front foot, 4 hind) and the single trunk finger of an Asian elephant. His wrinkled trunk was like that of an African elephant. His forehead was sloping with one dome and two smaller domes behind it. The body was African in type, but had an Asian-type centre hump and an African-type rear hump. The calf died of infection 12 days later. It is preserved as a mounted specimen at the British Natural History Museum, London. There are unconfirmed rumours of three other hybrid elephants born in zoos or circuses; all are said to have been deformed and none survived.
Despite its popularity in zoos, and cuddly portrayal as gentle giants in fiction, elephants are among the world's most potentially dangerous animals. They can crush and kill any other land animal, even the rhinoceros. They can experience unexpected bouts of rage, and can be vindictive. In Africa, groups of young teenage elephants attack human villages in what is thought to be revenge for the destruction of their society by massive cullings done in the 1970s and 80s. In India, male elephants attack villages at night, destroying homes and killing people on a regular basis. In the Indian state of Jharkhand, 300 people were killed by elephants between 2000 and 2004, and in Assam, 239 people have been killed by elephants since 2001. In India elephants kills up to 200 humans every year, and in Sri Lanka around 50 per year.
At least a few elephants have been suspected to be drunk during their attacks. In December 1998, a herd of elephants overran a village in India. Although locals reported that nearby elephants had recently been observed drinking beer which rendered them "unpredictable", officials considered it the least likely explanation for the attack. An attack on another Indian village occurred in October 1999, and again locals believed the reason was drunkenness, but the theory was not widely accepted. Purportedly drunk elephants raided yet another Indian village again on December 2002, killing six people, which led to killing of about 200 elephants by locals.
