All human societies go through fads in which they temporarily either adopt practices of little use or else abandon practices of considerable use.
The southward advance of native African farmers with Central African crops halted in Natal, beyond which Central African crops couldn't grow - with enormous consequences for the recent history of South Africa.
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.
Starbucks goes to a great effort, and pays twice as much for its coffee as its competitors do, and is very careful to help coffee producers in developing countries grow coffee without pesticides and in ways that preserve forest structure.
It's striking that Native Americans evolved no devastating epidemic diseases to give to Europeans, in return for the many devastating epidemic diseases that Indians received from the Old World.
Native Americans had only stone and wooden weapons and no animals that could be ridden. Those military advantages repeatedly enabled troops of a few dozen mounted Spaniards to defeat Indian armies numbering in the thousands.
