DNA evidence offers proof of North American native population decline due to arrival of Europeans

by Bob Yirka, Phys.org

Most history books report that Native American populations in North America declined significantly after European colonizers appeared, subsequent to the “discovery” of the new world by Christopher Columbus in 1492, reducing their numbers by half or more in some cases. Most attribute this decline in population to the introduction of new diseases, primarily smallpox and warfare.

To back up such claims, historians have relied on archaeological evidence and written documents by new world settlers. Up to now however, no physical evidence has been available to nail down specifics regarding population declines, such as when they actually occurred and what caused it to occur. Now however, three researchers with various backgrounds in anthropological and genome sciences have banded together to undertake a study based on mitochondrial DNA evidence, and have found, as they report in their study published in the Proceedings of the National Academy of Sciences, that native populations in North America did indeed decline by roughly fifty percent, some five hundred years ago.

What’s perhaps most interesting in the study, is the implication that the sudden drop in population appeared to occur almost right after the arrival of Europeans, which means before settlement began. This means that the decline would have come about almost exclusively as a result of disease sweeping naturally through native communities, rather than from warfare, or mass slaughter as some have suggested and that stories of settlers using smallpox as a weapon may be exaggerated.

Also of interest is that the researchers found that the native population peaked some 5,000 years ago, and held steady, or even declined slightly, until the arrival of Europeans, and that the population decline that occurred was transient, meaning that it gradually rebounded as those Native Americans that survived the initial wave of smallpox passed on their hearty genes to the next generation.

The results of this research also seem to settle the argument of whether the massive loss of life due to disease was regional, as some historians have argued, or widespread as others have claimed; siding firmly with the latter.

In studying the DNA, of both pre-European arrival native population samples and that of their ancestors alive today, the researchers noted that those alive today are more genetically similar to one another than were their ancestors, which suggests a population decline and then resurgence, and that is how, by backtracking, they came to conclude that the decline occurred half a century ago. The authors are quick to point out however that the margin of error in their work does allow for the possibility that the population decline occurred somewhat later than their results showed and note that further research will need to be done to create a more precise timeline of events.

Native Americans experienced a strong population bottleneck coincident with European contact, Brendan D. O’Fallona and Lars Fehren-Schmitz

PNAS, Published online before print December 5, 2011, doi: 10.1073/pnas.1112563108

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Americapox: The Missing Plague

By CGP Grey, an an educational YouTuber. He produces explanatory videos on science, politics, geography, economics, and history. This is a transcript of his video Americapox: The Missing Plague, www.cgpgrey.com/blog/americapox

Between the first modern Europeans arriving in 1492 and the Victorian age, the indigenous population of the new world [native American Indians] dropped by at least 90%.

The cause?

Not the conquistadores and company — they killed lots of people but their death count is nothing compared to what they brought with them: small pox, typhus, tuberculosis, influenza, bubonic plague, cholera, mumps, measles and more leapt from those first explores to the costal tribes, then onward the microscopic invaders spread through a hemisphere of people with no defenses against them. Tens of millions died.

These germs decided the fate of these battles long before the fighting started.

Now ask yourself: why didn’t Europeans get sick?

If new-worlders were vulnerable to old-world diseases, then surely old-worlders would be vulnerable to new world diseases.

Yet, there was no Americapox spreading eastward infecting Europe and cutting the population from 90 million to 9. Had Americapox existed it would have rather dampened European ability for transatlantic expansion.

To answer why this didn’t happen: we need first to distinguish regular diseases — like the common cold — from what we’ll call plagues.

1) Spread quickly between people.

Sneezes spread plages faster than handshakes which are faster than… closeness. Plagues use more of this than this.

2) They kill you quickly or you become immune.

Catch a plague and your dead within seven to thirty days. Survive and you’ll never get it again. Your body has learned to fight it, you might still carry it — the plague lives in you, you can still spread it, but it can’t hurt you.

The surface answer to this question isn’t that Europeans had better immune systems to fight off new world plages — it’s that new world didn’t have plagues for them to catch. They had regular diseases but there was no Americapox to carry.

These are history’s biggest killers, and they all come from the old world.

But why?

Let’s dig deeper, and talk Cholera, a plague that spreads if your civilization does a bad job of separating drinking water from pooping water. London was terrible at this making it the cholera capital of the world. Cholera can rip through dense neighborhoods killing swaths of the population, before moving onward. But that’s the key: it has to move on.

In a small, isolated group, a plague like cholera cannot survive — it kills all available victims, leaving only the immune and then theres nowhere to go — it’s a fire that burns through its fuel.

But a city — shining city on the hill — to which rural migrants flock, where hundreds of babies are born a day: this is sanctuary for the fire of plague; fresh kindling comes to it. The plague flares and smolders and flares and smolders again — impossible to extinguish.

Historically in city borders plagues killed faster than people could breed. Cities grew because more people moved to them than died inside of them. Cities only started growing from their own population in the 1900s when medicine finally left its leaches and bloodletting phase and entered its soap and soup phase — giving humans some tools to slow death.

But before that a city was an unintentional playground for plages and a grim machine to sort the immune from the rest.

So the deeper, answer is that The New World didn’t have plagues because the new world didn’t have big, dense, terribly sanitized deeply interconnected cities for plages to thrive.

OK, but The New World wasn’t completely barren of cities. And tribes weren’t completely isolated, otherwise the newly-arrived smallpox in the 1400s couldn’t have spread.

Cities are only part of the puzzle: they’re required for plages, but cities don’t make the germs that start the plagues — those germs come from the missing piece.

Now, most germs don’t want to kill you for the same reason you don’t want to burn down your house: germs live in you. Chromic diseases like leprosy are terrible because they’re very good at not killing you.

Plague lethality is an accident, a misunderstanding, because the germs that cause them don’t know they’re in humans, they’re germs that think they’re in this.

Plagues come from animals.

Whooping cough comes from pigs, and does flu as well as from birds. Our friend the cow alone is responsible for measles, tuberculosis, and smallpox.

For the cow these diseases are no big deal — like colds for us. But when cow germs get in humans thing things they do to make the cow a little sick, makes humans very sick. Deadly sick.

Germs jumping species like this is extraordinarily rare. That’s why generations of humans can spend time around animals just fine. Being the patient zero of a new animal-to-human plague is winning a terrible lottery.

But a colonial-age city raises the odds: there used to be animals everywhere, horses, herds of livestock in the streets, open slaughterhouses, meat markets pre-refrigeration, and a river of literal human and animal excrement running through it all.

A more perfect environment for diseases to jump species could hardly be imagined.

So the deeper answer is that plagues come from animals, but so rarely you have to raise the odds and with many chances for infection and give the new-born plague a fertile environment to grow. The old world had the necessary pieces in abundance.

But, why was a city like London filled with sheep and pigs and cows and Tenochtitlan wasn’t?

This brings us to the final level. (For this video anyway)

Some animals can be put to human use — this is what domestication means, animals you can breed, not just hunt.

Forget a the moment the modern world: go back to 10,000BC when tribes of humans reached just about everywhere. If you were in one of these tribes what local animals could you capture, alive, and successfully pen to breed?

Maybe you’re in North Dakota and thinking about catching a Buffalo: an unpredictable, violent tank on hooves, that can outrun you across the planes, leap over your head head and travels in herds thousands strong.

Oh, and you have no horses to help you — because there are no horses on the continent. Horses live here — and won’t be brought over until, too late.

It’s just you, a couple buddies, and stone-based tools. American Indians didn’t fail to domesticate buffalo because they couldn’t figure it out. They failed because it’s a buffalo. No one could do it — buffalo would have been amazing creature to put to human work back in BC, but it’s not going to happen — humans have only barely domesticated buffalo with all our modern tools.

The New World didn’t have good animal candidates for domestication. Almost everything big enough to be useful is also was to too dangerous, or too agile.

Meanwhile the fertile crescent to central Europe had: cows and and pigs and sheep and goats, easy pests animals comparatively begging to be domesticated.

A wild boar is something to contend with if you only have stone tools but it’s possible to catch and pen and bread and feed to eat — because pigs can’t leap to the sky or crush all resistance beneath their hooves.

In The New World the only native domestication contestant was: llamas. They’re better than nothing, which is probably why the biggest cities existed in South America — but they’re no cow. Ever try to manage a heard of llamas in the mountains of Peru? Yeah, you can do it, but it’s not fun. Nothing but drama, these llamas.

These might seem, cherry-picked examples, because aren’t there hundreds of thousands of species of animals? Yes, but when you’re stuck at the bottom of the tech tree almost none of them can be domesticated. From the dawn of man until this fateful meeting humans domesticated maybe a baker’s dozen of unique species the world over, and even to get that high a number you need to stretch it to include honeybees and silkworms. Nice to have, but you can’t build a civilization on a foundation of honey alone.

These early tribes weren’t smarter, or better at domestication. The old world had more valuable and easy animals. With dogs, herding sheep and cattle is easier. Now humans have a buddy to keep an eye on the clothing factory, and the milk and cheeseburger machine, and the plow-puller. Now farming is easier, which means there’s more benefit to staying put, which means more domestication, which means more food which means more people and more density and oh look where we’re going. Citiesville, population lots, bring your animals, plagues welcome.

That is the full answer: The lack of new world animals to domesticate, limited not only exposure to germs sources but also limited food production, which limited population growth, which limited cities, which made plagues in The New World an almost impossibility. In the old, exactly the reverse. And thus a continent full of plague and a continent devoid of it.

So when ships landed in the new world there was no Americapox to bring back.

The game of civilization has nothing to do with the players, and everything to do with the map. Access to domesticated animals in numbers and diversity, is the key resource to bootstrapping a complex society from nothing — and that complexity brings with it, unintentionally, a passive biological weaponry devastating to outsiders.

Start the game again but move the domesticable animals across the sea and history’s arrow of disease and death flows in the opposite direction.

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Don’t Blame Columbus for All the Indians’ Ills

By JOHN NOBLE WILFORD, OCT. 29, 2002, The New York Times

Europeans first came to the Western Hemisphere armed with guns, the cross and, unknowingly, pathogens. Against the alien agents of disease, the indigenous people never had a chance. Their immune systems were unprepared to fight smallpox and measles, malaria and yellow fever.

The epidemics that resulted have been well documented. What had not been clearly recognized until now, though, is that the general health of Native Americans had apparently been deteriorating for centuries before 1492.

That is the conclusion of a team of anthropologists, economists and paleopathologists who have completed a wide-ranging study of the health of people living in the Western Hemisphere in the last 7,000 years.

The researchers, whose work is regarded as the most comprehensive yet, say their findings in no way diminish the dreadful impact Old World diseases had on the people of the New World. But it suggests that the New World was hardly a healthful Eden.

More than 12,500 skeletons from 65 sites in North and South America — slightly more than half of them from pre-Columbians — were analyzed for evidence of infections, malnutrition and other health problems in various social and geographical settings.

The researchers used standardized criteria to rate the incidence and degree of these health factors by time and geography. Some trends leapt out from the resulting index. The healthiest sites for Native Americans were typically the oldest sites, predating Columbus by more than 1,000 years. Then came a marked decline.

”Our research shows that health was on a downward trajectory long before Columbus arrived,” Dr. Richard H. Steckel and Dr. Jerome C. Rose, study leaders, wrote in ”The Backbone of History: Health and Nutrition in the Western Hemisphere,” a book they edited. It was published in August.

Dr. Steckel, an economist and anthropologist at Ohio State University, and Dr. Rose, an anthropologist at the University of Arkansas, stressed in interviews that their findings in no way mitigated the responsibility of Europeans as bearers of disease devastating to native societies. Yet the research, they said, should correct a widely held misperception that the New World was virtually free of disease before 1492.

In an epilogue to the book, Dr. Philip D. Curtin, an emeritus professor of history at Johns Hopkins University, said the skeletal evidence of the physical well-being of pre-Columbians ”shows conclusively that however much it may have deteriorated on contact with the outer world, it was far from paradisiacal before the Europeans and Africans arrived.”

About 50 scientists and scholars joined in the research and contributed chapters to the book. One of them, Dr. George J. Armelagos of Emory University, a pioneer in the field of paleopathology, said in an interview that the research provided an ”evolutionary history of disease in the New World.”

The surprise, Dr. Armelagos said, was not the evidence of many infectious diseases, but that the pre-Columbians were not better nourished and in general healthier.

Others said the research, supported by the National Science Foundation and Ohio State, would be the talk of scholarly seminars for years to come and the foundation for more detailed investigations of pre-Columbian health. Dr. Steckel is considering conducting a similar study of health patterns well into European prehistory.

”Although some of the authors occasionally appear to overstate the strength of the case they can make, they are also careful to indicate the limitations of the evidence,” Dr. Curtin wrote of the Steckel-Rose research. ”They recognize that skeletal material is the best comparative evidence we have for the human condition over such a long period of time, but it is not perfect.”

The research team gathered evidence on seven basic indicators of chronic physical conditions that can be detected in skeletons — namely, degenerative joint disease, dental health, stature, anemia, arrested tissue development, infections and trauma from injuries. Dr. Steckel and Dr. Rose called this ”by far the largest comparable data set of this type ever created.”

The researchers attributed the widespread decline in health in large part to the rise of agriculture and urban living. People in South and Central America began domesticating crops more than 5,000 years ago, and the rise of cities there began more than 2,000 years ago.

These were mixed blessings. Farming tended to limit the diversity of diets, and the congestion of towns and cities contributed to the rapid spread of disease. In the widening inequalities of urban societies, hard work on low-protein diets left most people vulnerable to illness and early death.

Similar signs of deleterious health effects have been found in the ancient Middle East, where agriculture started some 10,000 years ago. But the health consequences of farming and urbanism, Dr. Rose said, appeared to have been more abrupt in the New World.

The more mobile, less densely settled populations were usually the healthiest pre-Columbians. They were taller and had fewer signs of infectious lesions in their bones than residents of large settlements. Their diet was sufficiently rich and varied, the researchers said, for them to largely avoid the symptoms of childhood deprivation, like stunting and anemia. Even so, in the simplest hunter-gatherer societies, few people survived past age 50. In the healthiest cultures in the 1,000 years before Columbus, a life span of no more than 35 years might be usual.

In examining the skeletal evidence, paleopathologists rated the healthiest pre-Columbians to be people living 1,200 years ago on the coast of Brazil, where they had access to ample food from land and sea. Their relative isolation protected them from most infectious diseases.

Conditions also must have been salubrious along the coasts of South Carolina and Southern California, as well as among the farming and hunting societies in what is now the Midwest. Indian groups occupied the top 14 spots of the health index, and 11 of these sites predate the arrival of Europeans.

The least healthy people in the study were from the urban cultures of Mexico and Central America, notably where the Maya civilization flourished presumably at great cost to life and limb, and the Zuni of New Mexico. The Zuni lived at a 400-year-old site, Hawikku, a crowded, drought-prone farming pueblo that presumably met its demise before European settlers made contact.

It was their hard lot, Dr. Rose said, to be farmers ”on the boundaries of sustainable environments.”

”Pre-Columbian populations were among the healthiest and the least healthy in our sample,” Dr. Steckel and Dr. Rose said. ”While pre-Columbian natives may have lived in a disease environment substantially different from that in other parts of the globe, the original inhabitants also brought with them, or evolved with, enough pathogens to create chronic conditions of ill health under conditions of systematic agriculture and urban living.”

In recent examinations of 1,000-year-old Peruvian mummies, for example, paleopathologists discovered clear traces of tuberculosis in their lungs, more evidence that native Americans might already have been infected with some of the diseases that were thought to have been brought to the New World by European explorers.

Tuberculosis bears another message: as an opportunistic disease, it strikes when times are tough, often overwhelming the bodies of people already weakened by malnutrition, poor sanitation in urban centers and debilitated immune systems.

The Steckel-Rose research extended the survey to the health consequences of the first contacts with American Indians by Europeans and Africans and the health of European-Americans and African-Americans up to the early 20th century.

Not surprisingly, African-American slaves were near the bottom of the health index. An examination of plantation slaves buried in South Carolina, Dr. Steckel said, revealed that their poor health compared to that of ”pre-Columbian Indian populations threatened with extinction.”

On the other hand, blacks buried at Philadelphia’s African Church in the 1800’s were in the top half of the health index. Their general conditions were apparently superior to those of small-town, middle-class whites, Dr. Steckel said.

The researchers found one exception to the rule that the healthiest sites for Native Americans were the oldest sites. Equestrian nomads of the Great Plains of North America in the 19th century seemed to enjoy excellent health, near the top of the index. They were not fenced in to farms or cities.

In a concluding chapter of their book, Dr. Steckel and Dr. Rose said the study showed that ”the health decline was precipitous with the changes in ecological environments where people lived.” It is not a new idea in anthropology, they conceded, ”but scholars in general have yet to absorb it.”

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