PRESIDENT ANDREW JACKSON. 'They have neither the intelligence, the industry, the moral habits, nor the desire of improvement which are essential to any favorable change in their condition.
Established in the midst of another and a superior race, and without appreciating the causes of their inferiority or seeking to control them, they must necessarily yield to the force of circumstances and ere long disappear.
CHIEF JUSTICE JOHN MARSHALL. 'The tribes of Indians inhabiting the country were savages, whose occupation was war, and whose subsistence was drawn from the forest…. That law which regulates, and ought to regulate in general, the relations between the conqueror and conquered was incapable of application to a people under such circumstances. Discovery [of America by
Europeans gave an exclusive right to extinguish the Indian title of occupancy, either by purchase or by conquest.
PRESIDENT WILLIAM HENRY HARRISON. 'Is one of the fairest portions of the globe to remain in a state of nature, the haunt of a few wretched
THE RISE AND FALL OF THE THIRD CHIMPANZEE savages, when it seems destined by the Creator to give support to a large population and to be the seat of civilization?
PRESIDENT THEODORE ROOSEVELT. 'The settler and pioneer have at bottom, had justice on their side; this great continent could not have been kept as nothing but a game preserve for squalid savages.
GENERAL PHILIP SHERIDAN. 'The only good Indians I ever saw were dead.
PART FIVE
REVERSING OUR PROGRESS OVERNIGHT
Our species is now at the pinnacle of its numbers, its geographic extent, its power, and the fraction of the Earth's productivity that it commands. That is the good news. The bad news is that we are also in the process of reversing all that progress much more rapidly than we created it. Our power threatens our own existence. We do not know whether we shall suddenly blow ourselves up before we would otherwise expire in a slow stew caused by global warming, pollution, habitat destruction, more mouths to feed, less food to feed those mouths, and extermination of other species that form our resource base. Are these dangers really new ones that arose since the Industrial Revolution, as widely assumed? It is a common belief that species in a state of nature live in balance with each other and with their environment. Predators do not exterminate their prey, nor do herbivores overgraze their plants. According to this view, humans are the unique misfit. If this were true, Nature would hold no lessons for us.
There is something to this view, insofar as species do not go extinct under natural conditions as rapidly as we are exterminating them now, except under rare circumstances. Such a rare event was the mass fatality sixty- five million years ago, possibly due to an asteroidal impact, that finished the dinosaurs. Since evolutionary multiplications of species are very slow, natural extinctions obviously must also be slow, otherwise we would have been left with no species long ago. Expressed alternatively, the vulnerable species get eliminated quickly, and what we see persisting in Nature are the robust combinations of species.
That broad conclusion still leaves us with many instructive examples of species exterminating other species. Almost all known cases prove to combine two elements. Firstly, the cases involve species reaching environments where they did not occur before, and where they encounter prey populations that are naive about the threat of those invading predators. By the time that the ecological dust settles and a new equilibrium is reached, some of the new-found prey may have been exterminated. Secondly, the perpetrators of such exterminations prove to be so-called switching predators, which are not specialized to eat only a single prey species but can feed on many different ones. Although the predator exterminates some prey, it survives by switching to others.
Such exterminations often occur when humans intentionally or accidentally transfer a species from one part of the globe to another. Rats, cats, goats, pigs, ants, and even snakes are among these transferred killers. For instance, during the Second World War a tree snake native to the Solomon Islands was accidentally transported on ships or planes to the previously snake-free Pacific island of Guam. This predator has already exterminated or brought to the brink of extinction most of Guam's native forest bird species, which had had no opportunity to evolve behavioural defences against snakes. Yet the snake is in no danger itself despite having virtually eliminated its bird prey, because it can switch to bats, rats, lizards, and other victims. As another example, cats and foxes introduced into Australia by humans have been eating their way through Australia's small native marsupials and rats without endangering themselves, because there remain abundant rabbits and other prey species on which to feed.
We humans furnish the prime example of a switching predator. We eat everything from snails and seaweed to whales, mushrooms, and strawberries. We can overharvest some species to the point of extinction, and then just switch to other food. A wave of extinctions has ensued every time that humans have reached a previously unoccupied part of the globe. The dodo, whose name has become synonymous with extinction, formerly lived on the island of Mauritius, half of whose land and freshwater bird species became extinct following the island's discovery in 1507. Dodos in particular were big, edible, flightless, and easily caught by hungry sailors. Hawaiian bird species similarly died out
Thus, there are numerous animal precedents for our propensity to exterminate individual prey species but to sustain ourselves by switching to others. Is there any precedent for an animal population destroying its entire resource base and eating its way into extinction? This outcome is uncommon, because animal numbers are regulated by many factors that tend automatically to lower birth rates or increase death rates when the animal is numerous, and vice versa when it is rare. For example, mortality due to external factors like predators, diseases, parasites, and starvation tends to increase at high population densities. Responses of the animal itself to high densities also contribute, such as infanticide, postponed breeding, and increased aggression. These responses and external factors generally reduce the animal's population and relieve its pressure on its resources before they can be exhausted.
Nevertheless, some animal populations actually have eaten themselves into extinction. One example involves the progeny of twenty-nine reindeer that were introduced in 1944 to St Matthew Island in the Bering Sea. By 1957 they had multiplied nearly fifty-fold to 1,350, by the year 1963 another four-fold to 6,000. But reindeer depend for food on slow-growing lichens, which on St Matthew had no chance to recover from reindeer grazing, since the animals had nowhere to migrate. When a harsh winter struck in 1963-64, all the animals except forty- one females and one sterile male starved to death, leaving a doomed population on an island littered with thousands of skeletons. A similar example was the introduction of rabbits to Lisianski Island west of Hawaii in the first decade of this century. Within a decade the rabbits had eaten themselves into oblivion by consuming every plant on the island except two morning glories and a tobacco patch. These and other similar examples of ecological suicide all involve populations that suddenly became free of the usual factors regulating their numbers. Rabbits and reindeer are normally subject to predators, and reindeer on continents use migration as a safety valve to leave an area and allow its vegetation to recover. But Lisianski and St Matthew Islands lacked predators, and emigration was impossible, so that the animals bred and ate unchecked. On reflection, it is clear that the entire human species has been equally successful in recently escaping from the former controls on our numbers. We eliminated predation on ourselves long ago; twentieth-century medicine has greatly reduced our mortality from infectious disease; and some of our leading behavioural techniques of population control, such as infanticide, chronic war, and sexual abstinence, have become socially unacceptable. Our population is now doubling about every thirty-five years. Granted, that is not as fast as the St Matthew reindeer, and Island Earth is bigger than St Matthew Island, and some of our resources are more elastic than lichens (though other resources, like oil, are less elastic). Yet the qualitative conclusion remains the same: no population can grow indefinitely.
Thus, our present ecological predicament has familiar animal precursors. Like many switching predators,
