December 8, 2011 | 2
One of the most iconic movie-monsters is without doubt the “mummy“, mostly from ancient Egypt and with human shape (despite the fact that thousands of animal mummies are known). Still today we are fascinated by the effort put into the preservation of these bodies, the ultimate victory above decay and death himself.
But there are not only artificial mummies. Natural mummies can be preserved in bog deposits, in tar pits, deep inside caves, glacier ice or permafrost – an environment too cold for an effective decomposition of organic matter.
At least 16 species of ice age mammals have been found mummified complete or partially: woolly mammoth, Shasta-, Jefferson´s- and Patagonian ground sloth, woolly rhinoceros, Yukon horse, steppe bison, helmeted muskox, Harrington´s mountain goat, caribou, giant moose, black-footed ferret, collared pika, snowshoe hare, arctic ground squirrel and vole. The ground sloths and mountain goats were found inside of caves. The woolly rhinoceros and mammoth of Starunia (Ukraine) became “pickled” in salty groundwater and coated by natural occurring mineral waxes.
Some of the best preserved and oldest natural mummies were found in thawing permafrost in Siberia, Alaska and Canada: like the 40.000 year old Russian mammoth calf “Dima” (discovered in 1977) or the 36.000 year old bison “Blue Babe” (discovered in 1979) from Fairbanks (Alaska) and a 40.000 year old black-footed ferret from the Yukon territory. Other exceptionally well preserved mammoth calves are “Lyuba” (2007), the 50.000 years old male “Khroma” (2009) and a new described calf found in the Siberian region of Yukaghir.
Fig.3. In the last 200 years many mummified mammoths were discovered in the thawing permafrost of Siberia. Considering the amount of fossil ivory commercialized in the same period, there must have been carcasses and bones of thousand of specimens.
Permafrost-mummies of extinct ice age mammals provide a variety of material for modern research – taxonomic relations and dispersal history can be studied trough the ancient DNA, the structure of soft tissue can be observed in detail, paleo diet can be inferred by the gut contents and faeces, some animals show pathological deformations or tissue changes and/or parasites. On some carcasses even the circumstances of the death can be deduced. The sediments covering the mummy can give clues for the reconstruction of the paleohabitat and the former climate.
But these mummies inspired also popular culture (apart the legends of still living mammoths). In the carcass of Khroma fossil bacteria were discovered, which could cause anthrax and black lung disease. Bacteria can theoretically survive long periods when frozen. In 2007 an international research team announced the discovery of 500.000 years old bacteria with intact DNA-sequence in samples of permafrost. To prevent any (and hypothetical) contamination of involved researchers, it was decided to sterilize the specimen with a massive dose of Gamma-rays.
The scenario of a still living pathogen or parasite inside a frozen and preserved body of an ice age mammal is also the main storyline of a TV-horror-production of 2009, named appropriately “The Thaw” (strangely the title for the German release is the exact opposite – “Frozen“). In a remote region of the Canadian tundra a carcass of mammoth is discovered in a melting glacier (prehistoric monsters entrapped in ice have a long tradition – see for example “The Beast from 20,000 Fathoms” in 1953, “Godzilla” in 1954 and “Dinosaurus!” in 1960).
This is a common misconception, the natural mummies discovered until now were preserved all in permafrost soil, which contains local ice lenses of secondary genesis. This ice however maybe plays an important role in the desiccation and preservation of the carcass, as moisture migrates from the body to the ice.
Anyway, the warming of the Canadian Arctic due anthropogenic climate change not only releases dead mammoths from the melting underground, but also a deadly and living pathogen – a parasite in form of an arthropod. To survive inside its host the parasite weakens the immune system (as some real parasites do), this behaviour would finally cause the death of the host if the flesh-eating bugs didn’t also multiply so fast that they eat their victim from inside.
The movie uses a environmental cause (the disease is released due the warming of the planet caused by our actions) as premise, most of the story is however clearly inspired from the movie “The Thing” (1982), even if in this movie the parasite, first hiding and then exactly copying its host, is an alien life-form.
The Thaw doesn’t really explain the origin of the parasite, but it seems almost certain that it is of terrestrial origin and also so deadly that it caused the extinction of the entire Pleistocene megafauna. The hypothesis of an unidentified hyperdisease killing entire species was proposed in 1997 after the first epidemics of Ebola in 1976-1979 and 1994-1996. Main vector of the presumed prehistoric pathogen was Homo sapiens, infecting mammoths and other large mammals during his travels around Siberia and North America. In 2006 a research on the pathological malformations of bones from American Mastodon (Mammut americanum) and bison bones suggested that the animals suffered from an infection of tuberculosis. A relatively large number of geographically and temporal separated individuals showed those malformations.
A recent example how dangerous pathogens can be for an isolated population was observed on the Christmas Islands in the Indian Ocean. In 1899 human colonization and introduced black rats (Rattus rattus) brought a unicellular parasitic protist (Trypanosoma) onto the islands. The endemic rat species (Rattus macleari & R. nativitatis) possessed no antibodies against the introduced parasite and the populations suffered a rapid decline – in 1904 both species were considered extinct. However this is an example on a very confined space, involving single species. It remains unclear how a single pathogen could wipe out so many species in such a short time on almost the entire planet.
The discovery of the well preserved mammoths inspired also another idea that today is still stuff for a science-fiction movie: the resurrection or cloning of a mammoth. One proposed scenario suggests using intact sperm or egg cells from a mummy to artificially inseminate a modern Asian elephant (the nearest living relative of the mammoth). A second scenario assumes that if the nucleus and DNA of a body cell is intact, it could be extracted and implanted in a modern elephant egg cell. After apposite stimulations the egg cell would grow to form a mammoth embryo. This theoretical approach is not new, already in 1980 Russian scientists made first attempts with genetic material from the mammoth calf Dima. In 1997 Japanese reproductive medics began a search for well preserved carcasses in Siberia. After the discovery of the Jarkov mammoth in the same year the optimistic scientists proclaimed that within a decade and with the advancement of cloning technology a living mammoth seemed feasible. However Jarkov was less well preserved than hoped and the recovered organic material to damaged to be useful.
Some promising (however in the end unsuccessful) attempts to clone recently extinct mammals from frozen samples were undertaken in the last years. In 2008 a nuclear transfer technology was used to clone mice from a specimen that was frozen for 16 years, however still less time than 10.000 years.
One of the greatest problems is the preservation of genetic material inside a frozen body. During the freezing process ice crystals form that could damage the cell, it is also unclear how long the DNA of vertebrates remains intact and active over long periods (natural occurring radiations can damage the DNA and the effects can accumulate over time).
Almost every discovery of a well preserved mammoth prompted the media to report about the mammoth cloning project, however many problems are still unsolved and a living mammoth will not so fast roam again the Siberian tundra, considered the most similar (however not the most appropriate) habitat to the ancient mammoth steppe.
The most important question remains: should we bring back a species extinct since the dawn of time? In the TV-horror-schlock “Mammoth” (2006) a partially frozen woolly mammoth is resurrected by alien technology, unfortunately it soon goes on a rampage killing people and causing havoc…
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JOHNSON, S.S. et al. (2007): Ancient bacteria show evidence of DNA repair. PNAS 104 (36): 14401-14405
ROTHSCHILD, B.M. & LAUB, R. (2006): Hyperdisease in the late Pleistocene: validation of an early 20th century hypothesis. Naturwissenschaften 93: 557-564
STONE, R. (2001): Mammoth – The Resurrection of an Ice Age Giant. Perseus Publishing, Cambridge USA: 271
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