If the past few months have felt like America's institutions and maybe society itself are falling completely apart, it could be because that's exactly what's happening.

History says so. So does anthropology. An expert in both disciplines says human civilizations provide a template for those societies that have come together, become steadily more complex, then head almost inexorably toward collapse.

Even the society that has risen up here between the shining seas is well down the same path, according to a widely cited and published historical anthropologist.

Joseph Tainter, who heads the department of environment and society at Utah State University, told the newspaper that the current course of the economy and what some believe is a desperate effort to shore up the complex and almost inscrutable financial sector of the economy are manifestations of at least a partial collapse that invariably follows a society's boom.

Tainter and his research are included in "Earth 2100," the ABC News assessment of how life might be 100 years from now. He is also a source in "The 11th Hour," actor Leonardo DiCaprio's documentary that connects the dots of how our doing ultimately leads to our undoing. Tainter's original research is published in the book "The Collapse of Complex Societies."

Tainter is not a doomsdayer, but his research amounts to a chilling prognostication that the very nature of civilization means that ours, like all the others, is destined to collapse.

"For the past 10,000 years, problem-solving has produced increasing complexity in human societies," Tainter said, noting that for every extra layer of organization imposed, it takes extra energy of the society to maintain. "And the more complex a society becomes, the more energy it takes to maintain it and the more it produces diminishing returns."

To keep growing, societies must keep solving problems as they arise. Yet success generates a larger population, more specialists, more resources to manage and more information to handle that ultimately provides less bang per buck.

Tainter sees diminishing returns as the underlying reason for the collapse of all ancient civilizations. Western industrial civilization has become bigger and more complex than any before it by exploiting new sources of energy, notably coal and oil, but these are limited, and constant innovation is needed.

The threat of a coming pandemic that would wipe out everyone rose again and seemed to quickly void, although briefly, the belief that our society has achieved a scale, a complexity and level of innovation that make it immune from collapse.

In fact, the opposite is true, Tainter said. "Possibilities range from little effect to a mild recession to a major depression to a collapse."

Looking at a previous society, the Roman Empire, he said as agricultural output slowly declined and population increased, per-capita energy availability dropped. The Romans "solved" this problem by conquering their neighbors to appropriate their energy surpluses (metals, grain, slaves, etc.).

However, as the empire grew, the cost of maintaining communications, garrisons and civil government grew with it. Eventually, this cost grew so great that any new challenges such as invasions and crop failures could not be solved by the acquisition of more territory. At that point, the empire fragmented into smaller units.

"When some new input to an economic system is brought on line, whether a technical innovation or an energy subsidy, it will often have the potential at least temporarily to raise marginal productivity," he said. "Eventually, barring continual conquest of your neighbors — which is always subject to diminishing returns — innovation that increases productivity is in the long run the only way out of the dismal science dilemma of declining marginal returns on added investments in complexity."

Tainter avoids conclusions and recommendations, but he believes in replacing the one thing that has allowed the United States to boom — oil — with the one thing that will forestall its collapse — renewable energy.

The complexity/collapse model also would explain the increase in the complexity of the American financial markets, their collapse, and the fragmenting of the banks and the auto industry.

E-MAIL: jthalman@desnews.com