In his Brief Description of New York (London, 1670), Daniel Denton says, in the quaint English of a son of a Presbyterian manse on 17th-century Long Island,

"To say something of the Indians, there is now but few upon the Island, and those few no ways hurtful but rather serviceable to the English, and it is to be admired, how strangely they have decreased by the Hand of God, since the English first settling of those parts; for since my time [Denton was born in 1644], where there were six towns, they are reduced to two small villages, and it hath generally been observed, that where the English come to settle, a Divine Hand makes way for them, by removing or cutting off the Indians either by wars one with the other, or by some raging mortal Disease."

Elsewhere in his panegyric of New York, which is really a plug for immigration, Denton praises its "sweet and pleasant Air, and a continuation of such Influences as tend to the Health both of Man and Beast." He notices no contradiction between the blooming health of the English and their livestock, and the fact that the Indians are dropping dead from raging mortal diseases. The remarkable decline in the Indian population that he reports has nothing to do with interracial conflict, for he describes the treaties and the trade that bind the communities as being mutually "serviceable." He would know all about that, because in 1662 and 1663 his job was to negotiate the purchase of lands from the natives. So the Divine Hand was encompassing the convenient reduction of the Indian population by means of (here Denton got them in the wrong order) internecine conflict between tribes, and diseases to which the English were immune and the Indians were not.

These two causes have continued to be the preferred explanation of the catastrophic decline in populations that attended all of Europe's encounters with the New World. Of course, there is a third cause to be invoked, the murder by Europeans of such of the natives as dared resist the loss of their land and its fruits. For those who press this argument, imported diseases are just excuses that spare the invader's responsibility on the grounds that, like Daniel Denton, he usually did not suspect what havoc his cough, his sneeze, his touch were wreaking. In this view, Denton's sanctimonious Divine Hand too often hides the bloodshed of the "wild frontier." And yet even when this powerful argument is pressed to the limit--and the limit is the cruel Spanish usurpation of established regimes in Central and South America--we are left with a massive loss of life that cutlass, musket and arquebuse could never inflict, least of all under a hail of spears and arrows.

The losses were enormous and by now beyond exact reckoning, because we do not know what the pre-contact populations were. Estimates for all the Americas range from 8 million to 112 million (and still rising); for America north of the Rio Grande from 900,000 to 18 million; for the Australian mainland from 300,000 to 1 million; and for tiny Tasmania from 500 to 7,000. In each case the bigger number comes from the critics of imperialism, who might be tempted to exaggerate the carnage, the smaller number from its apologists. (A scholar who analyzed these figures, David Henige, wisely called his book Numbers from Nowhere.) We do know that, starting from the most reliable estimates, native populations fell by about three-quarters in the first thirty or so years of contact (some by much more), and they continued falling steadily, because of disadvantage and alcohol, for 150 years, until an upturn began in the first half of the 20th century. Naturally, because of miscegenation, the descendents are genetically a quite different race from those who fell before the settlers, but they claim a cultural continuity that entitles them to reparation from the heirs of those guilty of the frontier murders (which engage responsibility more directly than the infections).

The study of these claims and responsibilities is a proper one for historians, though one constantly threatened by callous racism on one side and sentimental sloppiness on the other. It needs to be carried on in the light of two considerations: First, that it is a side issue, not the main matter; and second, that it is in a way irrelevant.

It is a side issue in that those "raging mortal diseases" were the main killer everywhere from the Valley of Mexico to California to the Australian outback. As to relevance, let us suppose that young Daniel Denton had stayed in the business of negotiating treaties and buying land, that he had made his peaceful way across the continent, a leonine treaty here, a shonky deal there, glass beads for priceless acres everywhere, and never a cross word. Let us suppose that when he had pacified California, the Canadians had borrowed him, and then (if only he had lived so long) the Australians, so that the British could build their second empire, all without spilling a drop of blood. Where would we be today? Just about exactly where we are. Three-quarters of the native peoples would have died on first contact with Europeans; sterility induced by venereal disease, alcohol, neglect and malnutrition would have reduced their numbers further; the invading herds and flocks would have displaced traditional food sources as the hunter-gatherers were everywhere pushed aside into reserves by the advancing cultivators and pastoralists. It did not happen that way, but this thought experiment is a reminder that any story of colonial settlement as first and foremost a series of massacres is bad history because it misses the main point. Murders were not uncommon, usually as revenge for livestock rustling or crop burning, but they are not the theme of the story of settlement.

But some stories tell it otherwise. Their favorite locale is Tasmania (Van Diemen's Land until 1855), where the British hastily founded a penal colony in 1803 for fear the French were about to claim it. Here, on empire's farthest shore, they proceeded, it is said, to massacre the natives. After years of warfare, in 1830 they formed a line of convicts, settlers and red-coated soldiers that advanced across the island and sought to corral the whole remaining population on to a peninsula. When that exercise failed ludicrously because they were no match for the blacks' bushman skills, they rounded the Aborigines up in small groups and shipped them offshore to windswept Flinders Island, where the last of the race died in 1876. In The Fatal Shore (Vintage, 1986), Robert Hughes called it the one instance of genocide in the history of the British empires. Others have called it a dry run for the Holocaust, a low-tech anticipation of concentration camps. Comparison with Pol Pot's killing fields has not been wanting. The doyen of Tasmanian historiography, Lyndall Ryan, authorized this rhetoric by declaring that the colonial government in Hobart had launched "a conscious policy of genocide."

In more temperate language, the Bullets-not-Bacteria school of colonial history has argued that the Aborigines of Tasmania were the legitimate defenders of their traditional territories against a violent British invasion; that many of them were killed in a long guerrilla war that was marked by repeated massacres of blacks; that the Aborigines demonstrated political savvy and, incidentally, good health throughout a brave but futile resistance; and finally, that unsupervised "borderers" (convicts working as shepherds and stockmen, sealers, bolters and bushrangers) raped, abducted or killed countless black women. That is why a precontact population of probably 2,000 (though some now say 5,000 to 7,000) had shrunk to 351 when they were rounded up for exile on Flinders Island.

Against this received version, a devastating attack has been launched by a Sydney historian, Keith Windschuttle, first in a series of articles in the Australian magazine Quadrant and then in The Fabrication of Aboriginal History (Macleay, 2002). In 480 pages of meticulous and occasionally mind-numbing detail, he claims to show that Britain's colonization of Australia was Europe's least violent encounter with the New World; that it met no organized resistance, only sporadic conflict; that mass killing by either side was rare and involved tens not hundreds of souls; that sustained frontier warfare was a fiction; and that there never was anything even resembling a genocide. He arrived at these conclusions by a method that was simple but tedious: He checked the footnote references of the orthodox histories. He discovered a tangle of mistakes and misinterpretations, references to documents that did not exist, quotations that had been twisted and truncated to mean the opposite, numbers that had been plucked out of the air, and a whole series of "fictions", "fabrications" and malicious inventions by academic historians who were also political militants.

Whereas these pro-Aborigine activists argued that thousands of natives were killed in a full-scale war (and, mysteriously, none by disease), Windschuttle did a careful body count of all recorded violent deaths on Tasmania. He found trace of 185 white deaths between 1803 and 1834 and, in the same period, only 118 black deaths, or about four a year. This was no war, because the primitive Tasmanians were incapable of organizing one. It was a series of thieving, murderous raids in quest of the white man's coveted tea and sugar, followed by limited revenge attacks, usually unsuccessful for want of bushman skills. True, the full-blood Aborigines died out during this wave of violence, but that was because they persisted in inter-tribal warfare (usually disputes over women) and because they prostituted their womenfolk to sealers, convict shepherds and anyone who would give in return tea, sugar, flour, blankets--and a dose of venereal disease.