Between 80% and 90% of the population of the western Hemisphere was dead within a century and a half of the arrival of Columbus, and nearly all of this was due to disease. A pre-1492 population of 100 million is a very high end estimate, a more realistic number is 40-50 million (or even 30-40 million), Reduce which ever estimate you prefer by 80-90%. There’s your death toll. Vast stretches of the New World were nearly depopulated and there were places with 100% mortality. The diseases spread at a stunning speed so that the Spanish were unaware of just how much mortality there had been because in many places they arrived several decades after the local population had been destroyed by smallpox, influenza, etc. By the time the English arrived in 1607 arrived there were far fewer Indians left to oppose them which allowed them to settle with far less resistance than they would have met a century and a half earlier. Much like California was well before the Spanish arrived, the eastern seaboard of what is now the United States had been very thickly populated. Disease struck well before Europeans arrived on either coast. Complex trade networks between tribes in pre-Colombian America assured that viruses brought with the conquistadores spread across both continents with stunning rapidity and virulence. In a population completely without immunities to any old world diseases–there had been no contact between residents of the western Hemisphere and residents of the eastern hemisphere for perhaps twenty thousand years–the mortality rate was astronomical. We have no way now of imagining what this was like. Indeed, the only peoples that do are uncontacted Amazonian tribes who die off rapidly after contact is made with the outside world. Each time that happens it is a microcosm of what happened in the Americans in that first hundred years after Columbus. (Interestingly, the same pattern of disease transmission devastated indigenous Australia as viruses followed the songlines between tribes.)
But what was bad for the Indians was a boon for the English. Germs had done all the dirty work for them. And it continued doing so. Indigenous populations were developing immunities and mortality rates declined, but even the most minor European malady–a mild flu, for instance–could lead to a pandemic with mass fatalities. The forests and fields were empty. Where they would have once met three or four million locals in powerful federated tribes, now they dealt with a tenacious tenth of that. Without old world diseases, Europeans would no more dominate the new world than they did in their colonies in Africa and India, with small white populations surrounded by a sea of the indigenes. That is because the Asians and Africans did not die from European born diseases. Indeed as often as not, the diseases began there. Neither Africa or Asia experienced a major drop in population from European colonization. Even the ravages of slave raids in the 17th and 18th century did not impact the population to a degree even remotely like the demographic devastation that struck the Americans from Alaska to Tierra del Fuego after the arrival of Columbus. The depopulation of the western hemisphere in the 16th century was unique. Horribly unique.*
The Spanish conquest hit the population of the Americas like a thermo-nuclear war. The loss of 80-90% of the population was a reasonable estimate of the cost of a U.S. or Soviet attack in the 60’s. The Spanish, via the germs that came with them, inflicted upon the Americas by far the worst human catastrophe in the history of the world. After the various plagues had done their work, settlement by English, French and Dutch was easy and profitable. Every European colonist brought with them the potential to unleash a devastating disease upon the local natives simply by sneezing or coughing. Tribes along the eastern seaboard began melting away as pathogens sapped them through sickness and death. Even as the centuries passed and immunities developed among the survivors, an Englishman’s common cold could lay low a native American, not necessarily killing him, but making him very sick. You have to wonder just how chronically ill indigenous Americans were in those first couple centuries. Remember these were people who suffered little from contagious diseases before Columbus. Suddenly they were sick all the time.
Everywhere the Europeans went, pathogens followed. French traders, trappers and monks like Cartier and Marquette inadvertently devastated entire populations around the Great Lakes region as they explored the interior of the continent by canoe, populations that had been spared some of the effects of the diseases brought a century earlier by the Spanish conquest. The French were more interested in trading with and converting the heathens than in colonizing, and the plagues they inadvertently unleashed devastated both their clientele and flocks. (Outside of Quebec and New Orleans, the French did very little in the way of settlements, which eventually cost them their stake in North America and sealed the fate of the American Indians.) There was no escape from invading microbes anywhere in the western hemisphere. Isolated villages in the Canadian arctic were devastated as late as a century ago, and in 1919 the Spanish flu inflicted nearly 100% fatalities in some Alaskan Inuit settlements. As I mentioned above, even today uncontacted tribes in the Amazon can suffer 90% mortality from illness when making contact with the outside world. And those people might be remnants of the estimated seven million people who once lived across the Amazon in large, complex societies. As modern investigative techniques–especially satellite photography–open up the Amazon to archeologists, evidence of large scale agriculture, irrigation, roads and urban areas that contained thousands of people are revealed. But that is all that remains of them. They have completely vanished. Pathogens would have come in from the Andes, where nine of every ten Incans died, or come in from the Atlantic coast. A few dozen conquistadores canoeing down the Amazon in search of gold might have killed hundreds of thousands of people simply by coughing. But we have no way of knowing for sure. All we know is that they were there in 1491, and gone a century later. Those small tribes of a few hundred or less who live deep in the jungle and attack helicopters with poison arrows may be all that survives of Amazonian civilization, like the handful of characters in a post-apocalyptic novel.
There are a number of excellent Wikipedia articles on the effects of the Spanish conquest on the population of the Americas. A side effect of this was the African slave trade. The Spanish purchased huge numbers of slaves brought over by the Portuguese from present day Angola to do the work that the Indian populations were too ill and dead or dying to perform. They began doing this in the mid 1500’s. Mexico City was built in part by African labor. The mass deaths in the New World were not part of the plan, something commonly misunderstood today. The Spaniards sought not only land and gold and glory, they sought subjects. The locals were suppose to supply the labor and taxes and farm production required by the Spanish empire but they died too soon. The difference had to be made up for with immigration from Spain. Hence Mexico is very much Spanish now, genetically, the Spanish men marrying the healthy indigenous women–and reducing the supply of mates for the indigenous men. The indigenous genetic component of the population just crashed, in particular the male genetic side. By the middle of the 17th century the population of central Mexico, once home to millions, was down to a few hundred thousand. That is a mortality and population reduction that is higher, much higher, than the death toll of the Black Plague (though in the Mediterranean littoral there were a few locales where the bubonic plague killed 90% of the population). And when the Spanish began exploring the gulf coast of North America, they came across empty settlements and scattered bones. The Plains Indian cultures we think of as having been there forever in the American Midwest were actually in large part the remnants of a much larger and more urbanized Mississippi Valley civilization. Our own Indian wars, like that of Mexico, were merely mopping up (it’s forgotten, by the way, that the Mexican government was engaged in a much bloodier war with the Apache for much longer than the US government. Mexico had inherited Spain’s Indian policy and it could be quite brutal.) The tribes in the New World fought like hell and inflicted far more casualties than they took, but their populations, devastated by disease, were small and eventually they were doomed to lose.
They simply could not muster the numbers needed to battle the Europeans. Perhaps two thousand warriors (among them some of my wife’s ancestors) defeated Custer at the Little Big Horn. But a British army was annihilated by ten thousand Ashanti in Ghana in 1823, another by thirty thousand Afghans in 1842, and yet another by twenty thousand Zulus in 1879. One hundred and twenty thousand Ethiopians routed the Italians in 1896. One hundred and twenty Sioux warriors were routed at Wounded Knee in 1890. Geronimo led an army of twenty four (24) men. There simply were not enough Indians to resist. In most parts of the Americas, the remaining locals were simply overwhelmed by immigrants. Pestilence had taken so many of them that there were not enough to hold their lands. The empty space seemed to beg for European immigrants. Without invasive diseases, though, the Americas might well today be as Native American as Africa is African.**
The initial waves of plague and pestilence had just been the beginning, of course. The survivors of those then faced centuries of wars and massacres and murder. There were long marches into exile. They were deprived of their living, their land, their language, even their families. The fact that there remain 566 federally recognized tribes within the United States (and another 600 in Canada) is a tribute to their extraordinary tenacity. In Mexico there are now nearly 16 million indigenous people, probably about as many as there were when Cortes landed. In two states–Quintana Roo and Oaxaca–they are in the majority. In Peru, which suffered a population loss exceeding even Mexico (well over 90%) by 1620, the population is now over a third indigenous and nearly half mestizo. Bolivia is over half full blooded indigene (including their president). Nearly half of Guatemala is indigenous. It’s taken five hundred years but indigenous populations are beginning to reach the numbers there were in 1491. But not everywhere. In Brazil there are 700,000 Indians, or about 15% of their 1491 population. But that’s up from 2% of a hundred years ago. And there are places in the Caribbean where there are no Indians left at all. There were at least a hundred thousand Taino on Hispaniola 1891, maybe considerably more. Spanish diseases and brutality reduced that population considerably. Then in 1518 smallpox killed 90% of those who remained. In 1548 a census found 500 surviving. The culture was extinct not long afterward. Today the Taino exist only as DNA.
The story of the Taino is a worst case scenario, clearly, but not the only one. History is replete with examples of people of all creeds and colors finishing off peoples of other creeds or colors in various ways. But rarely do a hundred thousand (or more) people disappear completely in a half century. Yet the Taino were gone. Only those of Spanish fathers survived, and a mestizo would not identify with the tribe of his mother. There was nothing to gain there, not in those times. So those Indians that do survive in the Americas are to be marveled at. At their stubbornness, their independence, their pride, their hardiness, their luck. They survived the greatest human disaster in the history of the world. War, massacres, brutality, slavery and exploitation certainly took their toll, but rarely are those enough to eliminate entire populations. Certainly not, under more normal considerations, a population a large as the Taino. But pathogens unleashed on a population with absolutely no natural immunities whatsoever? Remember how contagious disease and immune systems battle continuously to one up each other. They are finely tuned to each other’s weaknesses. And remember too how the diseases of Eurasia and Africa had been developing for fifty or a hundred thousand years since the ancestors of the American Indians had gone their separate ways in their trek through central Asia, across Siberia, over the Bering Sea land bridge and into America. In that time there had been no immunological defenses developed against any old world diseases at all. None. Zero. The Indians has absolutely nothing between the pathogens the Spaniards (and those who came later) and their internal organs. It was like shooting fish in a barrel. There has never been such a perfect killing arrangement before. These Indians were so vulnerable that a head cold could kill them. And something far, far worse, like smallpox, developed absolutely appalling symptoms. Everything developed extreme symptoms. Viruses developed to overcome tough immunological barriers engaged in appalling symptomatic overkill, which is why nine out of ten died. It took the development of H-Bombs before mankind devised something more destructive than unintentionally releasing pathogens on populations with no immunities at all. If you stop a minute here to think about that, the true horror will sink in.***
My wife and in-laws are all tribal (Sioux and Oneida). In fact my wife and her siblings are the first in her family line not born on a reservation. She is descended from the very few survivors of the waves of disease that swept her ancestors three centuries ago. She never gets sick. Not even colds. She has the most extraordinary immune system. Apparently that is why her ancestors survived when nearly everyone around them died.
Sometimes I wonder what it would be like if nine out of every ten people you knew was suddenly dead. It’s a lot like what happened to European Jewry, actually, who died at a similar rate between 1941 and 1945 (e.g., 3,000,000 out of 3,300,000 Polish Jews were killed). And what could have happened to all of us had nuclear war happened. I wonder, but I can never quite imagine it. Think of one hundred people you know–relatives, family, neighbors, coworkers. Write their names down on a list. Then pick out ten of them at random. Delete the rest. Those ten are the survivors. The other ninety are dead. Now reassemble your world using those ten survivors. Maybe you can. Maybe you can’t. But every Indigenous American alive today is descended from one of those ten.
* Unique on so grand a scale, anyway. For a smaller, but illustrative, example of mass mortality on a population with zero immunities, there is the British colony at Freetown in present day Sierra Leone. Established in 1792 as a base of operations for its anti-slave trade blockade, it was unfortunately deep in the African fever belt, with malaria and yellow fever and a number of other mosquito-borne diseases being not only endemic but pandemic. British efforts to maintain a garrison, officials, clergy and colonists in Freetown were met with a mortality rate that approached 90%. The first two governors died of malaria, and the third, terrified, deserted his post and fled back to England. Only continuous infusions of soldiers, sailors, assigned officials and extraordinarily brave clergymen kept the place going, most of them dying within weeks or months after arrival. One can only imagine had the English shipped a few thousand Irish refugees from the Potato Famine off to Freetown in the 1840’s. Eight or nine of every ten could easily have been dead with a year, a rate much like that of 16the century central Mexico, though perhaps even more complete as the diseases killing them would not be spreading from person to person as with smallpox among the Aztec but from the clouds of omnipresent mosquitos. Things were little better for the slaves freed from vessels the English patrols seized. Released in Freetown (hence the name) and unable to return home due to the thriving slave trade still in the interior of Africa, the freedmen died at a rate not as high as the English but high enough. The freedmen mortality rate would depend on where they had been seized by slavers. Those from the tropics would already have a degree of immunity to tropical diseases and would survive at a higher rate than those from further south. But the invention of quinine in the mid-nineteenth century brought the mortality rate from malaria, at least, down close to zero. (Yellow fever, more dangerous but never as pandemic as malaria, had to wait till the turn of the century for a vaccine. Some of the rarer fevers in Sierra Leone, like chikungunya, still have no vaccines.) Rarely considered in discussions of colonialism, there are vast stretches of the tropics that were opened up to colonization and exploitation by peoples of more nothern climes (Europeans, Americans, Japanese) only with the use of quinine. The Japanese failure to stock it in sufficient quantities helped them to lose their own tropical colonial empire in the 1940’s. Upwards of 90% of the Japanese soldiers left dead on New Guinea, Borneo and Guadalcanal died from untreated malaria. Indeed, the U.S. had no greater ally in those World War II jungle campaigns than the anopheles mosquito. A tale remarkably similar to that in the very next footnote, in fact.
** In one of the more brutal ironies of the colonial wars, in 1804 a French army devastated by yellow fever was annihilated by a larger army of freed slaves in Haiti. Yellow fever had been recently introduced into Haiti from Africa, coming no doubt in a slave ship. The slaves had some resistance to it, the French didn’t. The French colonialists were conquered by their own slaves and invasive disease in the same way that the Spaniards and smallpox had conquered the original Taino inhabitants of the island. Even the mortality rate–over 90%–was the same. Massacres took the rest. Both Taino and French disappeared from Haiti entirely. History has its little jokes.
*** Europeans got syphilis in return. The Spaniards, who’d race around the New World mounting everything that moved, picked up the syphilis virus. After those long frustrating sea voyages home, they immediately began their favorite activity again. You can follow the spread of the disease from Spanish ports and thence across Europe. Big cities became hotbeds of clap infection. The symptoms were ghastly, things fell off, noses eaten away, madness, death. In particular in its early years–again, the lack of immunities–it had the most grotesque effects. Not that anyone stopped infecting one another. You think it would have impeded desire but Europe just grew all the wilder. I suppose if there was any justice in these times, this was it.