Alfred Crosby:


"Ecological Imperialism" (Cambridge Univ Press, 1986)
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European emigrants and their descendants have spread all over the planet, and have become the main ethnic group in many places outside Europe: North America, Australia, New Zealand, and several countries of South America. These are the regions that Crosby calls "Neo-Europes". Crosby points out that Neo-Europes tend to enjoy food surpluses, and explains emigration by means of food production: Europeans were willing to leave the security of their homes as long as they were emigrating to places where it was feasible to reproduce the food production of their original lands. The deluge came between 1820 and 1930, when 50 million Europeans left Europe for Australia and the Americas. Add five million Russians who moved into Siberia between 1880 and 1913. The emigrants brought with them plants and animals that thrived in the new lands because the climate was similar to the one of their original lands. Basically, the Europeans proved very effective at building copies of Europe wherever the climate allowed it. In addition, they were helped by the fact that those distant lands did not harbor predators and parasites adapted to feed on the European plants and animals that those emigrants took with them. He blames the failure of the Crusades on one simple factor: the Europeans were not willing to settle in the Holy Land.

Crosby points out that, because of their passion for long-distance travel and trade, humans have always lived with an immune system that is chronically obsolescent. It is not clear, however, why Crosby thinks that Europeans had an advantage where the natives had a disadvantage: he points out that the natives were wiped out by diseases transported by the European immigrants, but why wouldn't the same problem represent a symmetrical disadvantage for the European immigrants? Each immune system was unprepared for the diseases of the other. Presumably there were many more biological dangers for the Europeans who came to live in alien lands than biological dangers created by the Europeans for the natives of those lands.

Crosby gives a detailed account of the history of weeds, pests and germs as they traveled from Europe to the Americas and Oceania, but rarely the other way. Several undesired species of European plants and animals spread wildly in the new continents, whereas no weed or pest came from the Americas to spread wildly in Europe.

Crosby also points out that of the two advantages that European civilization had over the American and Australian one (farming and domesticated animals), the most important was the domestication of animals. Europeans could avail themselves of horses, cows, pigs, goats, sheep, donkeys, chickens, cats, honeybees and many other domesticated animals that lived perfectly well in the new continents. The Americas only had the llama.

The main weapon that decisively favored the European invaders was the germs that killed millions of natives. Crosby points out that smallpox (imported from Europe) reached the Incas before the Spanish conquistadores did. By 1634 all the natives of Massachusetts had died of smallpox, and the huge population of the Southeast had disappeared by the time the French invaded it. There is no major disease that the New World exported to Europe and caused comparable devastation.

The solution to the paradox seems to be that the Europeans were the least isolated people in the world. Because they had always been in contact with so many other cultures (and therefore germs), they may have developed a stronger immune system by the time they reached the Americas. In fact, Crosby does not consider the most obvious candidate for forging a strong immune system in Europe: the black death that wiped out half of Europe in the 14th century. It is not true that Europe was never devastated by foreign germs the way the Americas were by European germs. That statement is true only after the "black death". There are theories that the Roman Empire itself was destroyed not by invading armies but by some kind of plague, exactly what happened to the Amerindian empires 1000 years later.

Whatever the reason, Crosby points out that the Amerindians lived in relatively "healthy" places, where they had to worry about very few diseases, and were unprepared for the diseases that came with the Europeans.

The animals coming from Europe enjoyed a similar advantage: South America was a relatively peaceful continent for chickens and horses compared with Eurasia and Africa where big carnivores abound. No wonder that horses, pigs, sheep and the likes (even camels in Australia) multiplied rapidly. Following Paul Martin, Crosby speculates that the big ferocious mammals had disappeared from the Americas because the first hunters had hunted them to extinction. In this sense the first wave of humans (thousands of years ago) wiped out the fauna that would have been an obstacle to the European fauna. When the second wave of humans arrived (from Europe), their fauna found a continent with precious few predators.

In turn, the animals helped spread the weeds that were coming from Europe. Seeds stuck to the hooves or to the hides or survived the digestion, and were carried from one place to another one. The weeds fed the European livestock, and the European livestock helped the seeds spread. The fact that Europeans plowed and fertilized the soil simply helped weeds to spread even more quickly.

The colonization of the Americas and Oceania was a team work in which humans, weeds, animals and viruses cooperated.