Mammoth

Mammoth Fossil range: Early Pliocene to Middle Holocene
Columbian mammoth in the George C. Page Museum, Los Angeles
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Proboscidea
Family:	Elephantidae
Genus:	†Mammuthus Brookes, 1828
Species
†M. africanavus African mammoth †M. armeniacus Armenian mammoth †M. columbi Columbian mammoth †M. exilis Pygmy mammoth †Mammuthus hayi †M. imperator Imperial mammoth †M. jeffersonii Jeffersonian mammoth †M. trogontherii Steppe mammoth †M. meridionalis Southern mammoth †M. subplanifrons South African mammoth †M. primigenius Woolly mammoth †M. lamarmorae Sardinian dwarf mammoth †M. sungari Songhua River mammoth

A mammoth is any species of the extinct genus Mammuthus. These proboscideans are members of Elephantidae, the family of elephants and mammoths, and close relatives of modern elephants. They were often equipped with long curved tusks and, in northern species, a covering of long hair. They lived from the Pliocene epoch from around 4.8 million to 4,500 years ago.^[1][2] The word mammoth comes from the Russian мамонт mamont, probably in turn from the Vogul (Mansi) language, mang ont, meaning "earth horn".^[3]

Size

Like their modern relative the elephant, mammoths were quite large; in English the noun "mammoth" has become an adjective meaning "large" or "massive". The largest known species, Songhua River mammoth (Mammuthus sungari) , reached heights of at least 5 metres (16 feet) at the shoulder. Mammoths would probably normally weigh in the region of 6 to 8 tons, but exceptionally large males may have exceeded 12 tons. However, most species of mammoth were only about as large as a modern Asian elephant. Fossils of species of dwarf mammoth have been found on the Californian Channel Islands (Mammuthus exilis) and the Mediterranean island of Sardinia (Mammuthus lamarmorae). There was also a race of dwarf woolly mammoths on Wrangel Island, north of Siberia, within the Arctic Circle.

A full size reconstruction of a mammoth species, the woolly mammoth, at Ipswich Museum, Ipswich, Suffolk

Cross-section of mammoth footprints (a type of trace fossil) at the Hot Springs Mammoth Site in South Dakota

An 11-foot (3.4 m) long mammoth tusk was discovered north of Lincoln, Illinois in 2005.^[4]

Based on studies of their close relatives the modern elephants, mammoths probably had a gestation period of 22 months, resulting in a single calf being born. Their social structure was probably the same as that of African and Asian elephants, with females living in herds headed by a matriarch, whilst bulls lived solitary lives or formed loose groups after sexual maturity.^[5]

Well-preserved specimens and prospects of cloning

In May 2007, the carcass of a one-month-old female woolly mammoth calf was discovered in a layer of permafrost near the Yuribei River in Russia, where it had been buried for 37,000 years. Alexei Tikhonov, the Russian Academy of Science's Zoological Institute's deputy director, has dismissed the prospect of cloning the animal, as the whole cells required for cloning would have burst under the freezing conditions. Nonetheless, DNA is expected to be well-enough preserved to be useful for research on mammoth phylogeny and perhaps physiology.^[6][7] However, Dr Sayaka Wakayama from the RIKEN Center for Developmental Biology in Kobe, Japan, believes that a technique she has used to clone mice from specimens frozen for sixteen years could be used successfully on recovered mammoth tissue: she cites that in her experiments the dead mice had been frozen to -20°C under simulated natural conditions, without using the usual preservative chemicals.^[8]

Researchers at Penn State University have sequenced about 85% of the gene map of the woolly mammoth, using DNA taken from hair samples collected from a selection of specimens, advancing the possibility of bringing the woolly mammoth back to life by inserting mammoth DNA sequences into the genome of the modern-day elephant. Although the samples were washed with bleach to remove possible contamination by bacteria or fungi, some DNA bases identified may be from the contaminating organisms and these have yet to be distinguished. To this end, scientists at the Broad Institute are currently generating a comparison with the genome of the African elephant.^[9][10][11] The information cannot be used to synthesize mammoth DNA, but Dr Stephan Schuster, leader of the project, notes that the mammoth’s genes differ at only some 400,000 sites from the genome of the African elephant and it would be possible (though not with presently available technology) to modify an elephant cell at these sites to make it resemble one bearing a mammoth's genome, and implant it into a surrogate elephant mother.^[12]

There is an estimate of 150 million mammoth remains in Russia's Siberian permafrost, which covers a vast sparsely inhabited area.^[13] Some of the remains are frozen complete, others in pieces of bone, tusk, tissue and wool, from less than a metre to 1 km below ground.^[13]

Extinction

Mammuthus armeniacus skull

Illustration of an Indian elephant jaw and a mammoth jaw from Georges Cuvier's 1796 paper on living and fossil elephants.

Full size life reconstruction of a mammoth (Mammuthus trogontherii).

The woolly mammoth was the last species of the genus. Most populations of the woolly mammoth in North America and Eurasia, as well all the Columbian mammoths in North America, died out around the time of the last glacial retreat, as part of a mass extinction of megafauna in northern Eurasia and the Americas. Until recently, it was generally assumed that the last woolly mammoths vanished from Europe and southern Siberia about 10,000 BC, but new findings show that some were still present there about 8,000 BC. Only slightly later, the woolly mammoths also disappeared from continental northern Siberia.^[14] A small population survived on St. Paul Island, Alaska, up until 3,750 BC,^[2][15][16] and the small mammoths of Wrangel Island survived until 1,650 BC.^[17][18][19]

A definitive explanation for their mass extinction is yet to be agreed upon. The warming trend (Holocene) that occurred 12,000 years ago, accompanied by a glacial retreat and rising sea levels, has been suggested as a contributing factor. Forests replaced open woodlands and grasslands across the continent. The available habitat may have been reduced for some megafaunal species, such as the mammoth. However, such climate changes were nothing new; numerous very similar warming episodes had occurred previously within the ice age of the last several million years without producing comparable megafaunal extinctions, so climate alone is unlikely to have played a decisive role.^[20][21] The spread of advanced human hunters through northern Eurasia and the Americas around the time of the extinctions was a new development, and thus probably contributed significantly.^[20][21]

Whether the general mammoth population died out for climatic reasons or due to overhunting by humans is controversial.^[22] Another theory suggests that mammoths may have fallen victim to an infectious disease. A combination of climate change and hunting by humans has been suggested as the most likely explanation for their extinction.

Data derived from studies done on living elephants suggest human hunting was likely a strong contributing factor in the mammoth's final extinction. Homo erectus is known to have consumed mammoth meat as early as 1.8 million years ago.^[23]

However, the American Institute of Biological Sciences also notes bones of dead elephants, left on the ground and subsequently trampled by other elephants, tend to bear marks resembling butchery marks, which have previously been misinterpreted as such by archaeologists.

The survival of the dwarf mammoths on Russia's Wrangel Island was due to the island's very remote location and lack of inhabitants in the early Holocene period. The European discovery of the island (by American whalers) did not occur until the 1820s. A similar dwarfing occurred with the pygmy mammoth on the outer Channel Islands of California, but at an earlier period. Those animals were very likely killed by early Paleo-Native Americans, and habitat loss caused by a rising sea level that split Santa Rosae into the outer Channel Islands.

Recent research indicates that mammoths survived on the American mainland until 10,000 years ago. This conclusion is from research, by James Haile and Eske Willerslev of the University of Copenhagen, of sediments found in central Alaska, and reported in the Proceedings of the National Academy of Sciences.^[22]

See also

• Elephant
• La Brea Tar Pits - cluster of tar pits located in Los Angeles, California, USA
• Mastodon
• Megafauna
• Pleistocene Park

References

Bibliography

• Capelli, Cristian; MacPhee, Ross D.E.; Roca, Alfred L.; Brisighelli, Francesca; Georgiadis, Nicholase; O'Brien, Stephen J.; Greenwood, Alex D. (2006): A nuclear DNA phylogeny of the woolly mammoth (Mammuthus primigenius). Molecular Phylogenetics and Evolution 40 (2) 620–627. doi:10.1016/j.ympev.2006.03.015 (HTML abstract). Supplemental data available to subscribers.
• Levy, Sharon (2006): Clashing with Titans. BioScience 56(4): 292-298. DOI:10.1641/0006-3568(2006)56[292:CWT]2.0.CO;2 PDF fulltext
• Lister, Adrian & Bahn, Paul (1994): Mammoths. MacMillan, London. ISBN 0-02-572985-3
• Martin, Paul S. (2005): Twilight of the mammoths: Ice Age extinctions and the rewilding of America. University of California Press, Berkeley. ISBN 0-520-23141-4
• Mercer, H.C. (1885): The Lenape Stone or The Indian and the Mammoth. DjVu fulltext PDF fulltext
• Stone, Richard (2001): Mammoth: The resurrection of an Ice Age giant. Fourth Estate, London. ISBN 1-84115-518-7

Notes

External links

• "Mammoth find. New evidence links Siberian, North American mammals", Little Mammoth from North America found in Siberia, in Canada National Post, September 5, 2008.
• "The Mammoth Story" by Grant Keddie - an article on the Royal British Columbia Museum website
• Mammoth Site of Hot Springs, South Dakota
• "The Great Mammoth Hoax"
• BBC: Mammoth skeleton found in Siberia
• "Back from the dead": A feature on efforts to clone mammoths back from extinction, Cosmos Magazine, 6 December 2006.
• Humans not responsible for mammoth extinction
• The Waco Mammoth Site
• Wenas Creek Mammoth Site The Wenas Creek Mammoth Project is a Central Washington University (CWU) scientific investigation of mammoth bones found on private land in the Wenas Creek Valley near Selah, Washington
• Mammoth Genome Cracked: Key to Cloning? in Cosmos Online.
• Smithsonian Magazine Features Mammoths and Mastodons