The Ice Ages

Calspace Courses

Climate Change · Part One
Climate Change · Part Two

      Climate Change 2 Syllabus

  1.0 The Ice Ages: An Introduction
         · 1.1 - General Overview of the Ice Ages
         · 1.2 - Mystery of the Mammoth Teeth

    2.0 - Discovery of the Ice Ages
    3.0 - Ice Age Climate Cycles
    4.0 - Climate Through the Last 1000 Years
    5.0 - Determining Past Climates
    6.0 - Causes of Millennial-Scale Change
    7.0 - Climate and CO₂ in the Atmosphere
    8.0 - Recent Global Warming
    9.0 - Climate Change in the Political Realm
    10.0 - The Link to the Ozone Problem
    11.0 - Future Energy Use
    12.0 - Outlook for the Future

Introduction to Astronomy
Life in the Universe

Glossary: Climate Change
Glossary: Astronomy
Glossary: Life in Universe

The Mystery of the Mammoth Teeth

(A) Drawing of a mammoth tooth and (B) Drawing of a mammoth as it would have looked during the Pleistocene.

The Land of the Giants

Consider the size and shape of a mammoth tooth. It is about 15 cm across, and just as high: The biggest grinding teeth in all of the animal kingdom, bar none, and wonderfully adapted to crush woody vegetable matter. Such teeth were found in the 18th century in several places in Siberia, attached to frozen carcasses. Thus, their origin is very well known. Later, in North America, beautifully preserved skeletons were found in the Rancho La Brea Tar Pits, in Hancock Park in Los Angeles. Most abundantly, we speculate, such teeth were found by people settling the shores of the North Sea in Europe when the glaciers had retreated, between 6000 and 8000 years ago or so. This is because when sea level was still low, at the end of the last ice age (called the "Wisconsin" in North America and "Würm" in northern Europe), mammoths roamed freely across the exposed shelf between the Netherlands and England. Their remains were later worked up by the waves, as the sea rose again across the shelf region. Rocks rolling in the surf readily crushed the bones, but the teeth of the mammoth are as tough as any rock, and they survived. Storm waves threw them up on the beach, all around the North Sea.

By the time the mammoth teeth were found by the new human settlers in the region, they had forgotten that mammoths ever existed. Or maybe they had only the dimmest of tribal memories inherited from the people who had lived side-by-side with the mammoth about an ancient race of giants and the other large Pleistocene mammals. These ancient tribes had hunted the mammoth and the other game and drawn them on cave walls in northern Spain and southern France (see figure below). They had long vanished when the ice finally freed the shores of Denmark — some ten thousand years earlier. In any case, the new settlers decided that the mammoth teeth were the remains of giants that once lived along the shore of the North Sea, in Denmark, and all around the Baltic, during a time when it was very cold. Based on the size of the teeth they calculated that the giants must have been about 70 feet tall; They named their new home "Land of the Giants" ("Friesland" and "Jutland"). And they assumed these ancient giants were the children of an enormous Ice Giant to the north who once ruled all of Scandinavia. When he was killed, his blood made the sea level rise and drowned his children. This explanation, preserved in Icelandic sagas, is the earliest recorded hypothesis of the existence of an ice age, whose end produced an associated rise of sea level, and resulted in the mass killing of these ancient giants. It was not so far off from the truth!

Sketch of the cave drawings of mammoths produced about 17,000 years ago from the Font de Gaume cave, France.

Georges Georges Cuvier and the Mammoths

These archaic ideas about an ancient flood which killed giant animals re-emerged in scientific writings in the early 19th century. The attempt to explain the mammoth teeth and the other remains from a vanished "Pleistocene megafauna" led to one of the greatest scientific discoveries of all time, one which changed our world view as much as the discovery that the Sun is in the center of the heavens, not the Earth. Mammoth teeth contained a most important clue to the history of life. What was this great scientific discovery based on mammoth remains? Extinction!

Though the concept was not easily accepted, extinction gave to paleontology a goal of profound intellectual challenge, far beyond that of recognizing and classifying fossils. There was much resistance from those who believed that the world was perfect, without much room for change. It was Baron Georges Cuvier [Full name: Georges Léopold Chrétien Frédéric Dagobert Cuvier] (1769-1832), a comparative anatomist and world expert on vertebrate zoology, who brought home the new idea in the latter 18th century. He showed that the mammoth, whose remains were found all over the temperate zones of Europe and Asia, was not identical to now existing elephants, but rather belonged to an extinct species. The argument that living representatives might be found in as yet unexplored corners of the world was unconvincing in this case. Clearly, the mammoth was too big to be overlooked, were it still roaming about.

Georges Cuvier not only established the geologically recent extinction of large mammals such as the woolly mammoth (Mammuthus primigenius) and the woolly rhinoceros (Coelodonta antiquitatis), but he also put forth the phenomenon of mass extinction, and proposed a cause: catastrophic changes on the surface of the earth. In particular, he suggested rapid sea-level changes, with inundation of low-lying areas, as an important mechanism. With reference to frozen mammoth in Siberian permafrost, he considered that abrupt climatic deterioration was the crucial agent responsible for both their death and preservation.