43 pages 1 hour read

Alfred W. Crosby

Ecological Imperialism: The Biological Expansion of Europe, 900-1900

Nonfiction | Book | Adult | Published in 1986

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Summary and Study Guide


Ecological Imperialism: The Biological Expansion of Europe 900-1900 was written in 1986 by historian Alfred W. Crosby. Crosby was a specialist in the study of historical disease, and in this book he broadens his focus to describe the ways in which European colonialism was not only a matter of European people moving worldwide but a wholesale takeover of entire ecosystems by plant, animal, and microorganism species originally from Europe. This guide refers to the Cambridge University Press 2nd edition.


The first half of the book is dedicated to outlining how Europeans were able to develop such a powerful colonial force. Europe’s set of advantages started deep in the past when Pangaea broke up and left the hominids’ ancestors in what would become Eurasia and Africa. While these areas experienced human habitation for millions of years, the rest of the world was left to develop without the influence of any large primates at all. Humans and their developing culture came to dominate the Old World landscape very quickly. During the low sea levels of the Pleistocene, a few humans crossed newly exposed land bridges into the Americas and Australia. These people would become the indigenous populations Europeans would later exploit and murder. Their disadvantages developed early: After sea levels rose they became isolated from Old World germs and cultural exchange with other humans. Between the end of the Pleistocene and the Early Middle Ages, humans in all areas lived without cross continental contact. The first proto-colonial efforts by the Norse Vikings and the Crusaders were not particularly successful but taught the Europeans important lessons about how to practice colonialism efficiently. After the Crusades failed, seafaring technology became a focus of wealthy European industrialists. The “discovery” of the islands off the coast of Africa, the Canaries, Azores, and Madeiras gave the Spanish and Portuguese a small scale on which to practice the type of colony building that would soon become common worldwide. Throughout the 14th-16th centuries, Europeans developed powerful boats and gained knowledge of the winds, and explorers began to make contact with land that had not been seen by outsiders since the original Pleistocene nomads.

Once sailing was a viable method of transportation across oceans, the practice of colonialism expanded rapidly. Spanish, Portuguese, French, and British colonists established settlements across the Americas. At first life in these settlements was harsh and deadly, but the European plants, animals, and microorganisms they brought with them thrived in many areas, and Europeans found that if they went to places climactically similar to Europe, they could establish a European lifestyle in just a few generations. This gave rise to the Neo-Europes, lands that were ecologically similar to Europe that had particularly vulnerable (i.e., easy to eradicate) locals and native biota that easily gave way to European species.

In the book’s second half, Crosby dedicates a chapter each to explaining how Old World animals, weeds, and diseases each played a part in the success of European colonialism. It ends with a case study of New Zealand, a Neo-Europe that stands out both in its unique native ecology and its relatively short period of any human habitation; the Māori are considered the indigenous New Zealanders but only arrived there about 1,000 years ago. Because of this, the entire history of humans in New Zealand is well documented, unlike in other Neo-Europes. It provides a valuable picture of how imperialism by ecological means is a critical aspect of the colonial picture.