There's never been a shortage of doomsday scenarios. From the dreaded Mayan Apocalypse of 2012 (remember that?) to the havoc wreaked in the movie "The Day After Tomorrow," people have been predicting the end of civilization for as long as there has been a civilization.
The trouble is, they're sometimes correct: The Roman Empire fell spectacularly, as did the Mayan civilization, the Han Dynasty of China, India's Gupta Empire and dozens of other once-mighty kingdoms.
But how, exactly, do powerful empires collapse, and why? Researchers now believe they've found an answer, one that has troubling implications for today — because we're clearly on the road to ruin. [11 Failed Doomsday Predictions]
Societal collapse — more common than you think
The researchers' first task was overturning "the common impression that societal collapse is rare, or even largely fictional," as they wrote in their report, to be published in the journal Ecological Economics. [Photos: Life and Death of an Ancient Civilization]
In fact, they argue, the rise and fall of great social structures is so common a theme in human civilization — recurrent throughout history and worldwide in scope — that it's more the rule than the exception.
Most studies of a society's collapse have looked at the specifics of how one civilization declined, citing individual causes such as a disaster (earthquake, flood), loss of resources (soil erosion, deforestation) or human conflict (war, uprising) that led to the particular society's downfall.
But the researchers (funded in part by NASA's Goddard Space Flight Center and the University of Maryland, College Park) cast a wider net. They aimed to create a useful mathematical model that could help analyze how any society might fall — including our current global, technically advanced, interconnected society.
The balance of nature
The model they arrived at takes inspiration from the classic notion of predator vs. prey, sometimes referred to as the "balance of nature." When a deer population grows, for instance, the wolves that feed on those deer reproduce more successfully, too, and so the wolf population grows.
Everything is fine until the wolves become too numerous and overreach, eating so many deer that there isn't enough venison to go around. Then, as the number of deer plunges, the wolf population drops due to famine, until equilibrium is reestablished and the cycle begins anew. [Civilization Doomed by Overconsumption, Wealth, Inequality (Infographic)]
Informed by this paradigm, the researchers developed a relatively simple formula with four factors influencing social collapse: nature and natural resources, the accumulation of wealth, the elite and the commoners. The team calls their model Human And Nature Dynamics, or HANDY.
A HANDY tool
The researchers used the HANDY model to analyze three different social scenarios: an egalitarian society with no elite class; an equitable society with workers and non-workers (students, retirees, disabled persons); and an unequal society with a robust class of elites.