Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.
Utah rock art depicts a domestic dog, whose earliest forerunners reached the Americas at least 10, years ago. Credit: Getty. Domestic dogs probably first arrived in North America with early human settlers from Siberia, only to be wiped out by Europeans half a millennium ago. The results were devastating. These populations also were introduced to new weeds and pests, livestock, and pets.
New food and fiber crops were introduced to Eurasia and Africa, improving diets and fomenting trade there. In addition, the Columbian Exchange vastly expanded the scope of production of some popular drugs, bringing the pleasures — and consequences — of coffee, sugar, and tobacco use to many millions of people. By far the most dramatic and devastating impact of the Columbian Exchange followed the introduction of new diseases into the Americas. When the first inhabitants of the Americas arrived across the Bering land bridge between 20, and 12, years ago, they brought few diseases with them.
For one reason, they had no domesticated animals, the original source of human diseases such as smallpox and measles. In addition, as they passed from Siberia to North America, the first Americans had spent many years in extreme cold, which eliminated many of the disease-causing agents that might have traveled with them.
As a result, the first Americans and their descendants, perhaps 40 million to 60 million strong by , enjoyed freedom from most of the infectious diseases that plagued populations in Afro-Eurasia for millennia. Meanwhile, in Asia and Africa, the domestication of herd animals brought new diseases spread by cattle, sheep, pigs, and fowl. Soon after , sailors inadvertently introduced these diseases — including smallpox, measles, mumps, whooping cough, influenza, chicken pox, and typhus — to the Americas.
People who lived in Afro-Eurasia had developed some immunities to these diseases because they had long existed among most Afro-Eurasian populations. However, the Native Americans had no such immunities. Adults and children alike were stricken by wave after wave of epidemic , which produced catastrophic mortality throughout the Americas. In the larger centers of highland Mexico and Peru, many millions of people died. On some Caribbean islands, the Native American population died out completely.
In all, between and , perhaps 90 percent of the first Americans had died. This loss is considered among the largest demographic disasters in human history. Ecosystems were in tumult as forests regrew and previously hunted animals increased in number. Economically, the population decrease brought by the Columbian Exchange indirectly caused a drastic labor shortage throughout the Americas, which eventually contributed to the establishment of African slavery on a vast scale in the Americas.
By , the slave trade had brought new diseases, such as malaria and yellow fever , which further plagued Native Americans. Eurasians sent much more than disease westward. Columbus had wanted to establish new fields of plenty in the Americas. On his later voyages he brought many crops he hoped might flourish there.
He and his followers brought the familiar food grains of Europe: wheat, barley, and rye. They also brought Mediterranean plantation crops such as sugar, bananas, and citrus fruits, which all had originated in South or Southeast Asia. At first, many of these crops fared poorly; but eventually they all flourished. After , sugar became the mainstay of the Caribbean and Brazilian economies, becoming the foundation for some of the largest slave societies ever known. The production of rice and cotton, both imported in the Columbian Exchange, together with tobacco, formed the basis of slave society in the United States.
Wheat, which thrived in the temperate latitudes of North and South America and in the highlands of Mexico, eventually became a fundamental food crop for tens of millions of people in the Americas. Indeed, by the late 20th century, wheat exports from Canada, the United States, and Argentina were feeding millions of people outside the Americas.
It is true that the spread of these crops drastically changed the economy of the Americas. However, these new crops supported the European settler societies and their African slave systems. The Native Americans preferred their own foods. When it came to animals, however, the Native Americans borrowed eagerly from the Eurasian stables. Stahl, Peter W. Journal of Archaeological Science — CrossRef Google Scholar.
Wheeler, Jane C. Biological Journal of the Linnean Society — Wing, Elizabeth S. Vuilleumier and M. Monasterio, pp. Oxford University Press, New York. Peter W. Stahl 1 1. It began in Tepeilhuitl. Large bumps spread on people; some were entirely covered. And when they made a motion, they called out loudly.
The pustules that covered people caused great desolation; very many people died of them, and many just starved to death; starvation reigned, and no one took care of others any longer. The New World had only a few, possibly because humans had been present there and had lived in dense populations, cities, for a short time compared to the Old. Possibly of greater importance is the relative lack of domesticated herd animals in America, one of our richest sources of disease micro-organisms.
0コメント