The World Without Us

Did mounting population exhaust the land, tempting Petexbatún rulers to seize their neighbors’ property, leading to a cycle of response that spiraled into cataclysmic war? If anything, Demarest believes, it was the other way around: An unleashed lust for wealth and power turned them into aggressors, resulting in reprisals that required their cities to abandon vulnerable outlying fields and intensify production closer to home, eventually pushing land beyond its tolerance.

“Society had evolved too many elites, all demanding exotic baubles.” He describes a culture wobbling under the weight of an excess of nobles, all needing quetzal feathers, jade, obsidian, fine chert, custom polychrome, fancy corbeled roofs, and animal furs. Nobility is expensive, nonproductive, and parasitic, siphoning away too much of society’s energy to satisfy its frivolous cravings.

“Too many heirs wanted thrones, or needed some ritual bloodletting to confirm their stature. So dynastic warfare heightened.” As more temples need building, the higher caloric demand on workers requires more food production, he explains. Population rises to insure enough food-producers. War itself often increases population—as it did in the Aztec, Incan, and Chinese empires—because rulers require cannon fodder.

Stakes rise, trade is disrupted, and population concentrates—lethal in a rain forest. There is dwindling investment in long-term crops that maintain diversity. Refugees living behind defensive walls farm only adjacent areas, inviting ecological disaster. Their confidence in leaders who once seemed all-knowing, but are obsessed with selfish, short-term goals, declines with the quality of life. People lose faith. Ritual activity ceases. They abandon centers.

A ruin at nearby Lake Petexbatún, on a peninsula called Punta de Chimino, turned out to be the fortress city of the last Dos Pilas k’uhul ajaw. The peninsula had been severed from the mainland by three moats, one cutting so deeply into bedrock that approximately three times the energy required to build the city itself was expended to dig it. “That’s the equivalent,” Demarest observes, “of spending 75 percent of a nation’s budget on defense.”

It was a desperate society that had lost control. The spear points the archaeologists discovered embedded in the fortress walls—including on the inside—testify to the fate of whoever ended up cornered on Punta de Chimino. Its monuments were soon eaten by the forest: in a world relieved of its humans, man’s attempts to make his own mountains quickly melt back into the ground.

“When you examine societies just as self-confident as ours that unraveled and were eventually swallowed by the jungle,” says Arthur Demarest, “you see that the balance between ecology and society is exquisitely delicate. If something throws that off, it all can end.”

He stoops, picks up a sherd from the moist ground. “Two thousand years later, someone will be squinting over the fragments, trying to find out what went wrong.”

4. Metamorphosis

From a wooden crate on the floor of his office at the Smithsonian’s National Museum of Natural History, paleobiology curator Doug Erwin pulls an eight-inch chunk of limestone he found in a phosphate mine between Nanjing and Shanghai, south of China’s Yangtze River. He shows the blackish bottom half, replete with fossilized protozoa, plankton, univalves, bivalves, cephalopods, and corals. “Life here was good.” He points to the faint whitish line of ash that separates it from the dull gray upper half. “Life here got really bad.” He shrugs.

“It then took a long time for life to get better.”

It took dozens of Chinese paleontologists 20 years of examining such rocks to determine that the faint white line represents the Permian Extinction. By analyzing zircon crystals infused in tiny glassy and metallic globules embedded in it, Erwin and MIT geologist Sam Bowring precisely dated that line to 252 million years ago. The black limestone lying below it is a frozen snapshot of the rich coastal life that had surrounded a single giant continent filled with trees, crawling and flying insects, amphibians, and early carnivorous reptiles.

“Then,” says Erwin, nodding, “95 percent of everything alive on the planet was wiped out. It was actually a thoroughly good idea.”