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Frozen mammals of the Ice Age, preserved for millennia in the tundra, have been a source of fascination and mystery since their first discovery over two centuries ago. These mummies, their ecology, and their preservation are the subject of this compelling book by paleontologist Dale Guthrie. The 1979 find of a frozen, extinct steppe bison in an Alaskan gold mine allowed him to undertake the first scientific excavation of an Ice Age mummy in North America and to test theories about these enigmatic frozen fauna.
The 36,000-year-old bison mummy, coated with blue mineral crystals, was dubbed "Blue Babe." Guthrie conveys the excitement of its excavation and shows how he made use of evidence from living animals, other Pleistocene mummies, Paleolithic art, and geological data. With photographs and scores of detailed drawings, he takes the reader through the excavation and subsequent detective work, analyzing the animal's carcass and its surroundings, the circumstances of its death, its appearance in life, the landscape it inhabited, and the processes of preservation by freezing. His examination shows that Blue Babe died in early winter, falling prey to lions that inhabited the Arctic during the Pleistocene era.
Guthrie uses information gleaned from his study of Blue Babe to provide a broad picture of bison evolutionary history and ecology, including speculations on the interactions of bison and Ice Age peoples. His description of the Mammoth Steppe as a cold, dry, grassy plain is based on an entirely new way of reading the fossil record.
THE CURSE OF THE FROZEN MAMMOTHS
Woolly mammoths, woolly rhinoceroses, steppe bison, and other mummies found in the frozen soil of the far north have fascinated us in both fiction and fact. Yet much about these animals—the environment in which they lived, and how they died and were preserved—is unknown or controversial.
In the summer of 1979, the frozen mummy of a steppe bison was unearthed at a placer gold mine just north of Fairbanks, Alaska. As the local specialist in Pleistocene mammals, I was asked to visit the site, and so began my involvement with the remains of the animal I came to call Blue Babe. This book is the story of Blue Babe and others of his kind. It is also an account of how we can look at the remains of an animal such as Blue Babe and reconstruct his history and his life, and a good deal of the world in which he lived and died. In this sense, this book is also a detective story, one that begins with the first studies of frozen mummies more than a hundred years ago.
Floaters or Sinkers
Modern views of the origin and history of the earth and the evolution of life itself had their origins in the first six decades of the nineteenth century, and naturalists in Europe were stimulated to develop new ideas and hypotheses in part by reports of the giant woolly mammoth carcasses found frozen in the ground in northeastern Asia. Parts of woolly mammoth and rhinoceros mummies were actually sent to Paris and London to satisfy the curiosity of naturalists and the public, which had become increasingly fascinated by the reports and finds of explorers and travelers who brought back tales and specimens of exotic plants and animals from around the globe.
The great geologist Charles Lyell supported the "floater" theory, arguing that the woolly mammoths and rhinoceroses, so much like the elephants and rhinos recently discovered in Africa, had lived in warmer climates in central Asia, had died in floods, and had subsequently been carried far northward in floodwaters (the major rivers in northern Asia really do flow north), where they had been frozen and buried. Georges Cuvier, the famous French anatomist, wrote a lengthy challenge to this idea in 1825. He observed that these animals were adapted to cold, with long, dense pelage and thick subcutaneous fat, and that they differed from living elephants and rhinos. Cuvier proposed that they were natives of the country where they were found. Hedenstrom (1830) joined Cuvier and showed that the carcasses of lower-latitude flood victims would have been destroyed long before they reached northern latitudes, and that the frozen carcasses and bones showed no signs of alluvial transport.
The Arctic explorer Middendorff (1848) continued to argue for river transport from milder, southern climates. An attempt at reconciliation was made by Howorth (1887), who proposed that these mammoths had lived in the north in a very warm climate that existed prior to the biblical flood and that they had been buried by silt when the waters receded. Since warmer climates did not return after the deluge, we find the presence of proscidians incongruent with northern cold. Lapparent still (1906) embraced Howorth's compromise in his famous Traité de géologie; however, in later editions of his book, Lapparent attributes the extinction of the mammoth to a gradual increase in cold and a decrease in the supply of food, rather than to a cataclysmic flood.
These controversies indirectly helped fund a number of successful expeditions commissioned by the Russian Academy of Sciences and an American Museum of Natural History expedition that was funded by J. Pierpont Morgan. After that later expedition, Quackenbush (1909) concluded that the partial mammoth mummy from Eschscholtz Bay, Alaska, was so deteriorated as to exclude "sudden fall in temperature" theories and that the mammoth had not been retransported after burial. The Russian and American expeditions obtained enough evidence to show that mammoths had indeed lived in the same areas in which their remains were found and that the former climate was as cold as now.
Once the issue was settled to the satisfaction of all, or nearly all, the next question was how the mummies had been buried. There were two main views. One was that the animals had fallen into a glacier crevasse or similar hole, often snow covered, but sometimes mud walled. Geikie (1881), in his major work on Pleistocene geology, championed the theory of Schrenk and Nehring that these creatures had been buried in snowstorms. The alternate view argued for some kind of entrapment in mud. These debates still continue.
Brandt (1866) was an adherent of the mud trap theory, as was Tolmachoff (1929) much later. Vollosovich (1909) also supported this idea and backed it with numerous anecdotes. He himself had been caught in such a mud trap and extricated only with the help of his guides. Vollosovich proposed that a trapped mammoth would effectively obstruct a small drainage, damming up mud and creating its own depositional environment.
There were many adherents to the snow-covered crevasse theory or some version of it, but the most influential of all was Digby (1926), who wrote a popular book titled The Mammoth and Mammoth Hunting in North East Siberia. Nevertheless, data from people who had seen these carcasses excavated indicated that the mammoths had been buried in mud rather than ice, although ice lenses were present around their carcasses. As I show, there are several interpretations for these ice lenses, and they form the basis of present-day theories about frozen mummies.
The Berezovka Mammoth
Until a few years ago, the Berezovka mammoth, excavated by Herz at the turn of the century, was the centerpiece of information about frozen mammoths. Unfortunately, this mummy was found before the days of rapid transportation, when it took a year for word to trickle back from Siberia to the Russian capital, Petrograd, and for an expedition to reach the site. In the winter of 1900, a cossack dealer in ivory mammoth tusks, named Yavlovski, bought a number of tusks from a Lamut tribesman on the Kolyma River. The tribesman, named Tarbykin, said he had chopped a pair of ivory tusks from one of the hairy beasts (Digby 1926). Yavlovski reported the statement to a local police official named Horn, who forwarded word to the governor general at Yakutsk, who in turn telegraphed the Imperial Academy of Sciences in Petrograd. This relay took several months, and it was not until May 1901 that an expedition set out to investigate Tarbykin's find. The expedition was led by Otto F. Herz (sometimes spelled Hertz), a zoologist on the Academy staff. He was accompanied by a geologist, M. D. P. Sevastianov, and a zoological preparator, M. E. V. Pfitzenmayer. It took them all summer to reach the site, where, hundreds of miles from the nearest source of supplies, they immediately began work on the mammoth. It was late September, and soon snow and frost began to hamper their work. They had to construct a log and canvas structure heated by a stove so that thawing and excavation could continue. According to the Lamut tribesmen, the head of the mammoth had been exposed two years before and many soft parts were already missing.
The mammoth was surprisingly well preserved but had undergone decomposition (fig. 1.1). In addition to its skin parts, some internal tissues such as the tongue were also well preserved (fig. 1.2). The mammoth even had food between its teeth, including flowers distinguished as buttercups. Herz described many other strange phenomena. In the early 1900s, the characteristics of Arctic frozen ground were strange to Europeans. Ice wedge features were wondrous things—"massive walls of ice," interpreted as underlying glaciers. Arctic explorers such as Kotzebue, Beechy, Stehanson, and Nelson (in Quackenbush 1909) had strange interpretations of this ice. They might indeed, for the origins of ice wedges are not intuitively obvious. These large ground ice formations were responsible for Herz's idea that the mammoth must have fallen into a snow-covered glacial crevasse, an idea that still survives. However, some of the ice lenses included parts of the mammoth, and much of its hair was embedded in ice.
Tales of earlier explorers suggested that mammoths ate pinecones. Herz was disappointed to find no pinecones or larch needles, but only bits of various grasses, in the large bolus of food frozen between the mammoth's teeth. Much of the animal's head had been eaten away by carnivores during the two years of exposure, but enough remained for Herz to find real information about mammoths. He and his associates were the first professionally trained biologists to see a mammoth mummy "in the flesh." Herz described hair color and length in detail, as well as other parts of the anatomy. The bare tail, for example, was short, only 14 inches (355 mm) long, with 10-inch (255 mm) hairs (fig. 1.3).
The death of the Berezovka mammoth seems to have been almost instantaneous. It had several broken bones—ribs, shoulder blade, and pelvis—and vertebrae were wrenched to one side. There were large blood clots in the viscera. It is possible, however, that some bones were broken diagenetically by the movement of sediments after burial. Despite a good description of the carcass, it is still unclear how the Berezovka mammoth died.
How the Berezovka mammoth was buried is likewise unknown. It may have been trapped in a cavity or mud sink as Herz suggests, but how it was buried remains a problem and probably does not relate directly to how and only indirectly to where it died. The geology of the site is sketchy, as one might assume that geologists from the early 1900s did not have a sophisticated understanding of the sedimentary features of reworked loess (fig. 1.4). The animal had about 3.6 inches (90 mm) of fat on its torso, suggesting that it was in good health and that it died in the late autumn, after a good summer's feeding. Fortunately, the Berezovka mammoth was brought back to Petrograd and saved for posterity.
This was the sum of our knowledge of frozen woolly mammoths for almost three-quarters of a century. Some very incomplete mummies were found in the interim, but until 1977, none was more informative than the Berezovka mammoth.
Perhaps the most famous frozen mummy from the far north is Dima, a baby mammoth found in the USSR in 1977 by a placer gold miner who was using a bulldozer to strip the thawed soils from underlying frozen ground. Dima was uncovered on a terrace of the Kirgiliakh River, a tributary of the Kolyma, north of Magadan in the Soviet Far East. Dima is perhaps the best-preserved specimen of all of the frozen large-mammal carcasses found in the far north. It had not been scavenged, so the carcass was intact (fig. 1.5), and very little decomposition had taken place before the body was frozen. A team of Soviet scientists was assembled to work with the mummy; they were able to conserve and analyze the specimen soon after discovery, and their analysis was quite thorough. The team included experts in paleontology, geology, geography, botany, palynology, entomology, histology, and anatomy. Each contributed a chapter to a monograph about Dima. Unfortunately, their book (Vereshchagin and Mikhel'son 1981) has not yet been published in English.
This team of experts generally agrees on basic data pertaining to Dima; their interpretations, however, vary widely. Each of the scientists who worked with Dima provides a scenario of his death and burial. Their report brings new life to the parable of the blind men and the elephant; each man, touching only part of the animal, describes a quite different beast.
Dima was truly a baby mammoth, just slightly over one meter high at the shoulder. Most hair had slipped, but much was found embedded in the mud where the animal laid. In fact, the hair actually helped the scientists, most of whom arrived at the site a little over a week after discovery, to relocate the exact spot where the carcass was found, because immediately after the discovery Dima had been moved to Magadan and refrozen. Dima's small size, lack of fat, and empty gut probably helped the carcass cool rapidly at the time of death, reducing the rate of decay so that even his viscera were well preserved. The carcass was virtually complete; only one side had been torn loose by the blade of the bulldozer at the time of discovery.
The Soviet team found a number of points of information pertinent to a reconstruction of Dima's death and preservation. The high quality of tissue preservation is itself unusual and indicates that the body cooled rapidly after death and was not subsequently exposed to long episodes of warm temperatures. The degree of completeness of the carcass is also unusual. Because there were no signs of scavenging by avian or mammalian carnivores, the carcass probably was not exposed to scavengers for any length of time.
Dima was a very young animal; judging from his size and the degree of tooth eruption and wear, his age was assessed at 7 to 8 months. His gastrointestinal tract was empty of food but contained plant detritus (unetched by stomach acids) and considerable amounts of mineral particles, silt, clay, and gravel. Most of the gut material (3.5 kg) was in his colon. "Many" hairs from the animal's own body were found in its gut, along with a few insect (Coleopteran) parts. The botanist identifying seeds from the gastrointestinal tract found them to be late summer to early winter in their degree of maturity; however, the team's palynologist found many pollen grains in the gastrointestinal tract that had not yet reached maturity. Mineral particles were not only found in the gastrointestinal tract, but also throughout the trachea, bronchi, and alveoli of the lungs. Dima was emaciated; no fat of any kind was present.
The animal lay on its left side, with the head pointing downslope and dipping down below the body. This position was fortunate, for it allowed the bulldozer blade to miss the head entirely. The animal was found about 2 m below the surface, where the zone of annual thaw is about 1.2 m. There was some ice around the carcass. Portions of ice were clear and others quite brownish yellow with mineral and organic particles. A very small wound was found on the lateral or outer side of Dima's right wrist, which showed some bruised tissue but no inflammation.
Radiocarbon dating showed that wood found immediately around the carcass had been buried from 9,000 to 10,000 yr B.P. However, a number of Soviet laboratory tests on the mummy's tissue gave dates in the range of 40,000 yr B.P. One tissue sample submitted to a lab in Pittsburgh, Pennsylvania, gave a date of 26,000 yr B.P. Histological evidence suggested that Dima contained a considerable number of helminth eggs. Other histological evidence showed that he had been under considerable physical exertion before death.
A few days prior to finding Dima, the same miner had unearthed a crushed horse head and legs with hooves. Because the miner thought this animal was a moose (Alces), he had not saved it, and the specimen was lost and could not be found. His descriptions of the hoof as "not split" helped the investigators conclude it had been a horse. Other horse bones and the bones of bison (Bison priscus) and woolly rhinos (Coleodonta antiquatus) were found in nearby sediments.
Excerpted from Frozen Fauna of the Mammoth Steppe by R. Dale Guthrie. Copyright © 1990 The University of Chicago. Excerpted by permission of The University of Chicago Press.
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