ANN ARBOR, Mich.Extensive studies of a 40,000-year-old baby mammoth carcass discovered in Siberia two years ago validate techniques developed by University of Michigan paleontologist Daniel Fisher for extracting information about prehistoric pachyderms' lives from their teeth and tusks.
Early results of the studies?which involved an international team of researchers and included CT scans, DNA analysis and surgical procedures in addition to tusk and tooth analyses?also are yielding insights into the young wooly mammoth's brief life and sudden death and clarifying aspects of mammoth ecology.
The discovery and subsequent studies of the baby mammoth, known as Lyuba, are the subject of a cover article in the May 2009 issue of National Geographic magazine. Fisher's work also is featured in ?Waking the Baby Mammoth,? scheduled to air Sunday, April 26 on the National Geographic Channel (9 p.m. ET/PT).
Lyuba was remarkably complete and well-preserved when discovered on a snowy riverbank in northwestern Siberia by a family of reindeer herders. Missing only toenails and most of her wooly coat, the mammoth looked very much like a sleeping baby elephant.
Realizing they had found something of great interest to the outside world, reindeer herder Yuri Khudi and local authorities arranged to have the mammoth airlifted to a museum in Salekhard, the regional capital. Fisher, who has been studying mammoths and mastodons for 30 years, was called in shortly after the discovery, and he, French Arctic explorer Bernard Buigues and Russian paleontologist Alexei Tikhonov were among the first to examine the carcass.
Although a number of other mammoth specimens have been found with soft tissues preserved, Lyuba stands out, said Fisher, who is the Claude W. Hibbard Collegiate Professor of Paleontology, with appointments in the U-M Museum of Paleontology and Departments of Geological Sciences and Ecology & Evolutionary Biology.
"What makes Lyuba different is the quality and completeness of her preservation," he said. "No other specimen preserves this much of the original anatomy."
Fisher was especially excited about the opportunity to study the teeth and nascent tusks of a mammoth whose nutritional status could be determined. Much of his previous work with mammoth and mastodon remains has focused on analyzing layers of dentin (ivory) in tusks, which contain a detailed record of the animal's life and health, just as growth rings tell a tree's life story. Chemical analyses of tusks also provide hints to what the animal ate and whether it was nutritionally stressed.
Though Fisher and graduate student Adam Rountrey have previously conducted such analyses, they've never had an opportunity to directly check the validity of their methods. "When has there ever been a mammoth that was well-enough preserved that you knew from looking at its tissues and gut contents what it ate and what condition it was in, so that you could check whether your conclusions from analyses of tusks and teeth were accurate?" Fisher said.
Previously, no such specimen was available, but Lyuba provided just what Fisher needed to validate his analyses. Traces of mother's milk in her intestines (the first milk residues ever found in a baby mammoth) and the fatty hump on the back of her neck were clear evidence that Lyuba was well nourished, and Fisher's analyses of tusk and tooth material agreed with that assessment.
"The methods that we have built over the years really do work, and this is the first time we've been able to show that so directly," Fisher said. The confirmation opens the door to broader application of the methods, which could help resolve the question of why mammoths became extinct.
These studies, together with CT scans performed at Jikei Univeristy School of Medicine in Tokyo, showed that Lyuba died suddenly at the age of one month. The team has not reached a consensus about her cause of death, but dense sediment packed into the mammoth's trunk, mouth and windpipe, along with a peculiar indentation at the base of her trunk, suggest she died of asphyxiation in mud.
"What seems to have happened is, she fell into a goopy slurry of mud and sand, which sometimes develops along the margins of these riverbanks, and somehow got her head submerged and sucked in a lot of mud," Fisher said. "It filled her airways, and she was unable to cough it out."
Another intriguing question is how Lyuba avoided decomposition and destruction. Undoubtedly she was frozen in permafrost for most of the time between her death and discovery, but Fisher and Buigues determined that the carcass lay on the riverbank for nearly a year before the reindeer herders stumbled upon it.
"That means that this baby mammoth, flesh and all, sat out on the side of the river all of the Arctic summer of 2006, which would have subjected the carcass to 24-hour-a-day sunlight, elevated temperatures and exposure to bacteria and scavengers," Fisher said. "So why is it preserved as well as it is?"
Based on previous experiments aimed at understanding how Paleolithic hunters stored meat from large animal kills, Fisher believes Lyuba was naturally pickled in lactic acid produced by microbes called lactobacilli. The pickling would have protected her body from decomposition, and the sour smell likely deterred scavengers.
In addition to Fisher, Rountrey, Buigues and Tikhonov, researchers involved in the baby mammoth project include Naoki Suzuki (Jikei University), Hendrik Poinar (McMaster University), James Tiedje (Michigan State University), Marianne McKelvy (The Dow Chemical Company), Bas van Geel (University of Amsterdam), Frank R