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A frozen baby mammoth found in the Russian Arctic has been analyzed with computed tomography (CT), revealing an intact heart, liver, and other organs. Researchers from the Russian Academy of Science's Zoological Institute in St. Petersburg collaborated with experts at the Jikei University School of Medicine in Tokyo, who recently returned the animal to Russia after performing extensive CT analyses in their laboratories.1
Yuri Khudi, a reindeer herder of the Nenets, an indigenous Russian population, found the baby female mammoth carcass along a river on the Yamal Peninsula in Northwest Siberia in May of 2007. He named the mammoth Lyuba, after his wife. His discovery quickly generated interest among scientists, including Russian paleontologist Alexei Tikhonov and French adventurer Bernard Buiges, who jointly organized the expedition to recover the mammoth's remains.
Researchers have estimated that Lyuba was approximately 6 months old at the time of her death and was quickly buried in a low-oxygen environment, such as a marsh or bog, based on the high quality of the remains. Aside from a portion of her tail and ear, her body was fully intact but was missing most of its wooly coat.
The carcass remained frozen in the permafrost for approximately 37 000 years, until its removal by the expedition scientists. The intact carcass has raised hopes among the researchers that advanced diagnostic strategies could be used to answer important questions about the mammoths, the environment in which they lived, and the possible reasons for their demise. Without definitive evidence, scientists continue to debate that the mammoth extinction was either primarily due to climate change or over-hunting by humans. Meanwhile, recent research using climate models and fossil distribution patterns suggests that their demise was, in fact, a combination of both climate change and human intervention.2
The intact skin of the mammoth protected its internal organs from modern microbial exposure, making Lyuba an exciting prospect for researchers interested in conducting genetic, molecular, and microbiological analyses of the animal, Tikhonov explained.
Khudi's discovery has also contributed to an ongoing public debate about the urgency of climate change. Akito Arima, the head of the Science Museum in Tokyo where the mammoth was recently displayed, suggested that global warming could have played a role in the discovery of the mammoth carcass, although he declined to offer a scientific explanation for his statement.3 The melting of the permafrost could have caused the carcass to be exposed after being hidden for centuries. The prospect of melting permafrost has been a cause for concern both because it is a sign of substantial warming and because large amounts of carbon-trapping gases could potentially be released during the thawing process.3
Initial CT Findings
Heading the CT analysis at Jikei University School of Medicine, Naoki Suzuki discussed the initial findings during a January press conference held in Tokyo (Figure). Although many of the findings have yet to be released to the public, Suzuki noted that all of the animal's major organs were found intact and an "almost surgical view" of the animal's internal structure was possible. Tikhonov explained, "We can see all the internal organs in their natural positions."4
Researchers in Russia continue to analyze data from the animal's CT scans. Sergey Grishin, director of the Shemanovsky Yamal-Nenets Museum, explained that 3-dimensional CT data are now being used to characterize the internal organs and structure of the mammoth, and could also be used to get a better idea of Lyuba's diet and the exact cause of her death.
Initial CT analyses confirm that Lyuba apparently suffered no wounds prior to her death and was found to have taken in a good amount of mud and silt, suggesting that she drowned and was quickly submerged. The researchers also found that Lyuba's diet was restricted to mother's milk, which is consistent with their predictions, as modern elephants are not weaned for the first few years of life.
Suzuki stressed that Lyuba represents scientists' best chance so far to discover "everything about the mammoth," adding that the study of Lyuba could have implications in definitively characterizing the factors that played a role in the extinction of the mammoth.
Next Steps for Lyuba
Now that the initial CT scans of the animal have been completed, Lyuba has been returned to St. Petersburg for tissue and bone biopsies. Not only will these studies give researchers insight into the structure of the mammoth's organs, glands, and muscle tissue, but scientists also hope to learn more about the prehistoric plant life and viruses that were common to the animal's environment. For instance, researchers are hoping to isolate DNA fragments from prehistoric viruses present in Lyuba's tissue, the first time that this has been possible from an animal specimen. Analyses of Lyuba's intestines could likewise reveal ancient pollen and plant spores, which could help scientists better envision the landscape that Lyuba once roamed, said Tikhonov.
Air samples left in the lungs are also being analyzed to get a better picture of the Earth's atmosphere during the ice age that defined Lyuba's environment.
Although researchers from North America and Russia are now vying for the opportunity to study DNA samples from Lyuba in an effort to fully decode the mammoth genome, Tikhonov stressed that the mammoth is not a likely candidate for a species that could be brought back from extinction through cloning, largely because the environmental conditions that were hospitable to the animal no longer exist in today's climate. However, he added that the study of the mammoth genome could assist researchers hoping to clone other animals back into existence.
Those interested in additional information about Lyuba and advanced radiologic modalities used in archaeology and paleontology applications can access the following resources:
National Geographic: Baby Mammoth CT Scan Reveals Internal Organs
High-Resolution X-Ray CT Facility at the University of Texas, Austin, Department of Geological Sciences: Biological and Paleontological Examples
1. National Geographic News. Baby Mammoth CT Scan Reveals Internal Organs. Available at: http://news.nationalgeographic.com/news/2008/04/080411-baby-mammoth.html. Accessed July 25, 2008.
2. Science Daily. Climate Change and Human Hunting Combine to Drive the Wooly Mammoth Extinct. Available at: http://www.sciencedaily.com/releases/2008/03/080331223843.htm. Accessed July 31, 2008.
3. MSNBC.com. Mammoth Could Shed Light on Warming. Available at: http://www.msnbc.msn.com/id/22504161/. Accessed July 25, 2008.4. National Geographic News. Baby Mammoth's Innards Scanned. Available at: http://news.nationalgeographic.com/news/2008/04/photogalleries/mammoth-pictures/photo2.html. Accessed July 28, 2008.