Mammoth

? Mammoth Conservation status: Prehistoric
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Proboscidea Family: Elephantidae Genus: Mammuthus Brookes, 1828
Species
Mammuthus columbiColumbian mammoth Mammuthus exilisPygmy mammoth Mammuthus jeffersoniiJeffersonian mammoth Mammuthus meridionalis Mammuthus primigeniusWoolly mammoth Mammuthus lamarmoraeSardinian Dwarf Mammoth

A mammoth is any of a number of an extinct genus of elephant, often with long curved tusks and, in northern species, a covering of long hair. They lived during the Pleistocene epoch from 1.6 million years ago to around 10,000 years ago. The word mammoth comes from the Russian мамонт ("mamont").

Evolutionary history

Mammoth remains have been found in Europe, Africa, Asia, and North America. They are believed to have originally evolved in North Africa about 4.8 million years ago, where bones of Mammuthus africanavus have been found in Chad, Libya, Morocco and Tunisia. Despite their African ancestry, they are in fact more closely related to the modern Indian elephant than the African elephant. The common ancestor of both mammoths and Asian elephants split from the line of African elephants about 6 - 7.3 million years ago. The Asian elephants and mammoths diverged about half a million years later (5.5 - 6.3 million years ago).

In due course the African mammoth migrated north to Europe and gave rise to a new species, the southern mammoth (Mammuthus meridionalis). This eventually spread across Europe and Asia and crossed the now-submerged Bering Land Bridge into North America.

Around 700,000 years ago, the warm climate of the time deteriorated markedly and the savannah plains of Europe, Asia and North America gave way to colder and less fertile steppes. The southern mammoth consequently declined, being replaced across most of its territory by the cold-adapted steppe mammoth (Mammuthus trogontherii). This in turn gave rise to the woolly mammoth, Mammuthus primogenius) around 300,000 years ago. Woolly mammoth was better able to cope with the extreme cold of the Ice Ages.

The woollies were a spectacularly successful species; they ranged from Spain to North America and are thought to have existed in huge numbers. The Russian researcher Sergei Zimov estimates that during the last Ice Age, parts of Siberia may have had an average population density of sixty animals per hundred square kilometres - equivalent to African elephants today.

Extinction

Most mammoths died out at the end of the last Ice Age. However, the dwarf mammoths of Wrangel Island became extinct only around 1700 to 1500 BCE. Whether the general mammoth population died out for climatic reasons or due to overhunting by humans is controversial. A third theory suggests that mammoths may have fallen victim to an infectious disease. A definitive explanation has yet to be agreed upon, and it is very possible that a combination of factors was responsible rather than any of the single cause. The survival of the dwarf mammoths on Russia's Wrangel Island was due to the fact that the island was very remote, and uninhabited in the early post-Pleistocene period. The actual island was not discovered by modern civilization until the 1820s by American whalers. A similar dwarfing occurred with Mammoths on the outer Channel Islands of California, but at an earlier period. Those animals were very likely killed by early paleo-indians.

Mammoths and cryptozoology

There have been occasional claims that the mammoth is not actually extinct, and that small isolated herds might survive in the vast and sparsely inhabited tundra of the northern hemisphere. In the late 19th century, there were according to Sjögren (1962) persistent rumours about surviving mammoths hiding in Alaska. In October 1899, a man named Henry Tukeman said to have killed a mammoth in Alaska, and donated the specimen to the Smithsonian Institution in Washington. But the museum in question denied the existence of any mammoth corpse, and it turned out to be a hoax. Sjögren (1962) believes the myth got started when the American biologist C.H. Townsend traveled in Alaska, and saw Eskimos trading mammoth tusks, and asked if there still were living mammoths in Alaska and provided them with a drawing of the animal.

In the 19th century, several reports of "large shaggy beasts" were passed on to the Russian authorities by Siberian tribesman, but no scientific proof ever surfaced. A French charge d´affaires working in Vladivostok, M. Gallon, claimed in 1946 that he in 1920 met a Russian fur-trapper that claimed to have seen living giant, furry " elephants" deep into the taiga. Gallon added that the fur-trapper didn´t even know about mammoths before, and that he talked about the mammoths as a forest-animal at a time when they were seen as living on the tundra and snow (Sjögren, 1962). There was an alleged Soviet Air Force sighting during World War II, but this was not verified by a second sighting.

Size

It is a common misconception that mammoths were much larger than modern elephants, an error that has led to "mammoth" being used as an adjective meaning "very big". Certainly, the largest known species, the Imperial Mammoth of California, reached heights of at least 4 meters (13 feet) at the shoulder. Mammoths would probably weigh in the region of 6-8 tons. [1]. However, most species of mammoth were only about as large as a modern Indian elephant, and fossils of a species of dwarf mammoth have been found on Wrangel Island off the east coast of Siberia.

Adaptations

Mammoths had a number of adaptations to the cold, most famously the thick layer of shaggy hair, up to 50 cm (20 in) long, for which the woolly mammoth is named. They also had far smaller ears than modern elephants; the largest mammoth ear found so far was only a foot (30 cm) long, compared to six feet (1.8 m) for an African elephant. They had a flap of hairy skin which covered the anus, keeping out the cold.

Their teeth were also adapted to their diet of coarse tundra grasses, with more plates and a higher crown than their southern relatives. Their skin was no thicker than that of present-day elephants, but unlike elephants they had numerous sebaceous glands in their skin which secreted greasy fat into their hair, improving its insulating qualities. They had a layer of fat up to 8 cm (3 in) thick under the skin which, like the blubber of whales, helped to keep them warm.

Mammoths had extremely long tusks - up to 16 feet (5 m) long - which were markedly curved, to a much greater extent than those of elephants. It is not clear whether the tusks were a specific adaptation to their environment, but it has been suggested that mammoths may have used their tusks as shovels to clear snow from the ground and reach the vegetation buried below.

Preserved remains; Genetic Evidence

Preserved frozen remains of woolly mammoths have been found in the northern parts of Siberia. However, the popular notion that these bodies were 'flash frozen' and perfectly preserved is a myth propogated by authors such as Immanuel Velikovsky. Preservation is a rare occurrence, essentially requiring the animal to have been buried rapidly in liquid or semi-solids such as silt, mud and icy water which then froze.

This may have occurred in a number of ways. Mammoths may have been trapped in bogs or quicksands and either died of starvation or exposure, or drowning if they sank under the surface. They may have fallen through frozen ice into small ponds or potholes, entombing them. Many are certainly known to have been killed in rivers, perhaps through being swept away by river floods; in one location, by the Berelekh River in Yakutia in Siberia, more than 9,000 bones from at least 156 individual mammoths have been found in a single spot, apparently having been swept there by the current.

To date, thirty-nine preserved bodies have been found, but only four of them are complete. In most cases the flesh shows signs of decay before its freezing and later desiccation. Stories abound about frozen mammoth corpses that were still edible once defrosted, but the original sources (e.g. William R. Farrand's article in Science 133 [March 17, 1961]:729-735) indicate that the corpses were in fact terribly decayed, and the stench so unbearable that only the dogs accompanying the finders showed any interest in the flesh.

In addition to frozen corpses, large amounts of mammoth ivory have been found in Siberia. Mammoth tusks have been an article of trade for at least 2,000 years. They have been and are still a highly prized commodity. Güyük, the 13th century Khan of the Mongols, is reputed to have sat on a throne made from mammoth ivory, and even today it is in great demand as a replacement for the now-banned export of elephant ivory.

Since there is a known case in which an Indian elephant and an African elephant have produced a live (though sickly) offspring, it has been theorised that if mammoths were still alive today, they would be able to interbreed with Indian elephants.

This has led to the idea that perhaps a mammoth-like beast could be recreated by taking genetic material from a frozen mammoth and combining it with that from a modern Indian elephant. Scientists hope to retrieve the preserved reproductive organs of a frozen mammoth and revive its sperm cells. However, not enough genetic material has been found in frozen mammoths for this to be attempted. The complete mitochondrial genome sequence of Mammuthus primagenius has been determined, however (J. Krause et al, Nature 439,724-727, 9 Feb 2006). The analysis demonstrates that the divergence of mammoth, African elephant, and Asian elephant occurred over a short time, and confirmed that the mammoth was more closely related to the Asian than to the African elephant.

As an important landmark in this direction, in December 2005, a team of German, UK & American researchers were able to assemble a complete mitochondrial DNA of the mammoth, which allowed to trace the close evolutionary relationship between mammoth and Asian elephant. African elephants branched away from the woolly mammoth around 6 million years ago, a moment in time intriguingly close to that of the similar split between gorillas, chimps and humans.

Origins of the name

The name "mammoth" comes via Russian from the Tatar language. It may have its origins in the Tatar word mamma, "earth", alluding to the long-held belief that mammoths lived underground and made burrows. The 17th century traveller Eberhard Ysbrant Ides recorded that the Evenk, Yakut and Ostyak peoples of Siberia believed that the mammoths "continually, or at least by reason of the very hard frosts, mostly live under ground, where they go backwards and forwards." Exposure to the air was enough to kill them, explaining why they were never seen alive.

Mammoth Teeth

The teeth of mammoths are quite distinctive. They are composed of a set of compressed enamel plates that are held together with cementum. These cemented plates make a very tall, strong, and wear-resistant tooth. After a tooth erupts from the gum cavity, the mammoth uses it in grinding coarse vegetation like grass. This use causes the tooth to develop a flat top with low enamel ridges where the plates have been worn.

The tall structure of these hypsodont (shallow-rooted) teeth make them very resistant to wear. This is important because mammoths are thought to have been primarily grass-eaters. Grass is a very hard material to eat. It has small pieces of silica (a glass-like substance) in its leaves. These pieces of silica act like sandpaper grit and would wear away a less resistant tooth very quickly.

Mammoths are frequently found as fossils in the midwestern U.S. Most often isolated teeth are found. Mammoth fossils are most common in areas that were covered by savannas, grasslands, or tundra during the last Ice Age. This map shows some of the important mammoth finds in the region.