This
essay appears in the fall/winter 2001–2002 issue of Early Awareness of Extinction Although extinction has been going on for as long as there has been life on the planet, humans have only recently become aware of it. We first began to understand what fossils were only 200 years ago. Even after educated people accepted that fossils were the remains of long-dead creatures, they were reluctant to believe that such creatures were extinct. At the end of the eighteenth century, biological theory was wrapped in the idea of the Great Chain of Being, which argued that by removing one link (species) the whole chain could break. Thomas Jefferson, after studying the fossil of a giant ground sloth dug up in western Virginia (which he misidentified as a lion), wrote in 1799, “If this animal has once existed, it is probable on this general view of the movements of nature that he still exists.”1 He asked Meriwether Lewis and William Clark to be on the lookout for living counterparts to the fossil animals being found. At the time of Jefferson’s writing, French scientist Georges Cuvier was convincing most natural historians that the fossils being unearthed in Europe were of extinct animals. Religious scientists thereupon revised earlier theories to allow for extinction in God’s perfect plan. The evidence for extinct mammals grew as more fossils were dug up and described. By 1825, for example, ten extinct North American vertebrates had been described. After scientists settled on the reality of extinction, the "how" remained to be answered. Suggested mechanisms for extinction depended on whether one was a catastrophist or a uniformitarian. Cuvier proposed localized catastrophes to explain extinctions, while others, led by William Buckland of England, looked to Noah’s flood as the universal catastrophe that accounted for extinct species. Swiss geologist and biologist Louis Agassiz, who emigrated to the United States and became one of the foremost American scientists of his era, argued for mass glaciation as the cause of past extinctions. Buckland went over to Agassiz’s glacier theory in 1842.2 English geologist Charles Lyell was the “early champion of slow, natural changes across the surface of the earth as a cause of Pleistocene extinctions.” According to Donald Grayson, Lyell believed that “the extinction of species is a predictable, natural, and ongoing phenomenon, one that can be expected to occur slowly during the course of ages.”3 Although the reality of extinction of species was well accepted before mid-century by both catastrophists and uniformitarians, Lyell and other advocates of gradual, natural extinctions had a hard time explaining what the actual mechanisms of extinction were. In both North America and Europe, other scientists, including France’s Jean-Baptiste de Monet de Lamarck, suggested that humans had caused past extinctions. Lyell rejected human causation because he believed the extinctions occurred before humans were present. However, by the 1860s, the great French bone digger Jacques Boucher de Perthes changed the minds of Lyell and others. Boucher de Perthes’s careful, stratigraphic excavations in the Somme River valley proved that early man and the extinct great beasts were contemporaries. After visiting Boucher de Perthes’s diggings in 1859, Lyell wrote, “That the human race goes back to the time of the mammoth and rhinoceros (Siberian) and not a few other extinct mammals is perfectly clear.…” In 1860, British anatomist Richard Owen acknowledged extinction of the fossil beasts by the “spectral appearance of mankind on a limited tract of land not before inhabited.” Alfred Russell Wallace, intrepid explorer and codiscoverer with Darwin of natural selection, believed in catastrophic glaciation and thus rejected human causation even after Lyell, Owen, and Darwin accepted it. Finally, after the turn of the century, Wallace accepted that glaciation had not been so widespread as he had believed, and, in concert with climatic changes, “the extinction of so many large Mammalia is actually due to man’s agency.…”4 Based on the evidence in the ground, by the last half of the nineteenth century educated people recognized that prehistoric extinctions had occurred and that it was likely that Stone Age humans had a hand in them. During that same period, some began to turn their eyes to evidence that new extinctions were then taking place and that humans were again responsible. In 1832, nearly three decades before he accepted Boucher de Perthes’s views that humans had hunted extinct beasts, Lyell wrote that “the annihilation of a multitude of species has already been effected, and will continue to go on hereafter, in a still more rapid ratio, as the colonies of highly civilized nations spread themselves over unoccupied lands.”5 It was not long after Lyell’s warning that many hunters and naturalists in North America called for an end to the mass slaughter of bison, passenger pigeon, and waterfowl then taking place. Civilizations, in fact, have recorded extinctions since 80 A.D., when the European lion became extinct.6 In 1914, famous naturalist William T. Hornaday of the New York Zoo delivered a stirring series of lectures on wildlife conservation at the Yale School of Forestry, which were published as a widely read book, Wild Life Conservation. He listed 10 species that had become “totally extinct in a wild state between 1840 and 1910”: Great
auk, The magnitude of the extinction crisis, however, remained invisible, even to most conservationists and biologists, through much of the twentieth century. Extinction was a problem that conservationists sought to stay, but its enormity—that the modern extinction event was of the magnitude of the dinosaur extinction event—was unimagined. However, in 1936, leading American conservationist Aldo Leopold, after a trip to inspect German forests, wrote in Bird-Lore that “the most pressing job in both Germany and America is to prevent the extermination of rare species.”8 In 1963, British conservationist Colin Bertram reviewed the status of wildlife in the British nature journal Oryx and expressed his fear: “Even the minority, the preservationists and conservationists, in my opinion, have as yet failed to see in full the awful vividness of the red light before them.” He warned that “without sufficient [human] fertility control, we lose inevitably and for ever most of the remaining larger mammals of the world, very many of the birds, the larger reptiles and so many more both great and small.”9 University of Wisconsin botanist Hugh Iltis spoke on the first Earth Day in 1970 at the University of Michigan. He warned that we were “pushing, prematurely, tens of thousands of species of plants and animals toward the abysmal finality of extinction by destroying their habitats, by decimating their numbers, by interrupting their life cycles and ruining their supply of food.”He said, “Today, 10% to 12% of the mammalian taxa can be considered to be endangered, and birds are faring no better.”10 The dawning awareness that we were witnessing an extinction event to rival or surpass that of the dinosaurs became widespread in the 1970s with the rapidly accelerating destruction of tropical forests. Geneticist Michael Soulé, a cofounder of the Society for Conservation Biology and the Wildlands Project, credits British botanist and tropical conservationist Norman Myers with being the first to publicly say we were in a mass extinction. In 1978, The Wilderness Society excerpted in their magazine a Worldwatch Institute report by Erik Eckholm summarizing the latest thinking on worldwide extinction by Myers, Peter Raven of the Missouri Botanical Garden, tropical ecologist Thomas Lovejoy, David Ehrenfeld, and other biologists. Eckholm warned: Within sight is the destruction of plant and animal species, and of the genetic heritage of eons they embody, on a scale that dwarfs the combined natural and human-caused extinctions of the previous millions of years. Should this biological massacre take place, evolution will no doubt continue, but in a grossly distorted manner. Such a multitude of species losses would constitute a basic and irreversible alteration in the nature of the biosphere even before we understand its workings—an evolutionary Rubicon whose crossing Homo sapiens would do well to avoid.11 More than 20 years ago, then, the conservation movement had every reason to be fully aware of the crisis. By 1980, Soulé and Bruce Wilcox had edited a state-of-knowledge book on the crisis and possible solutions—Conservation Biology.12 In the foreword, Lovejoy wrote, “Hundreds of thousands of species will perish, and this reduction of 10 to 20 percent of the earth’s biota will occur in about half a human life span.…This reduction of the biological diversity of the planet is the most basic issue of our time.”13 Soulé and Wilcox wrote, “There is simply no precedent for what is happening to the biological fabric of this planet and there are no words to express the horror of those who love nature.”14
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