The adoption of agriculture, supposedly our most decisive step toward a better life, was in many ways a catastrophe from which we have never recovered.

One way to explain the complexity and unpredictability of historical systems, despite their ultimate determinacy, is to note that long chains of causation may separate final effects from ultimate causes lying outside the domain of that field of science.

History as well as life itself is complicated -- neither life nor history is an enterprise for those who seek simplicity and consistency.

Even to this day, no native Australian animal species and only one plant species-the macadamia nut-have proved suitable for domestication. There still are no domestic kangaroos.

Measles and TB evolved from diseases of our cattle, influenza from a disease of pigs, and smallpox possibly from a disease of camels. The Americas had very few native domesticated animal species from which humans could acquire such diseases.

All recognized famous inventors had capable predecessors and successors and made their improvements at a time when society was capable of using their product.

We study the injustices of history for the same reason that we study genocide, and for the same reason that psychologists study the minds of murderers and rapists... to understand how those evil things came about.