The history of humankind has been marked by patterns of growth and
decline. Some declines have been gradual, occurring over centuries.
Others have been rapid, occurring over the course of a few years. War,
drought, natural disaster, disease, overpopulation, economic disruption:
any of these or a combination of these events can bring about the
collapse of a civilization. Internal causes (such as political struggles or
overfarming) can combine with external causes (such as war or natural
disaster) to bring about a collapse. What does this mean for modern
civilizations? What can we learn from the past?