Two professionals from different fields but with similar interests say the fate of the ancient inhabitants of the Four Corners foreshadows what lies in store for moderns who try to wrest from the environment more than it can give.

Jim Judge, a retired archaeologist, and Dr. Richard Grossman, a practicing gynecologist with a deep interest in population issues, will draw a parallel between ancestral Puebloans and today's business community at a Green Business Roundtable lunch Wednesday.

The cautionary tale of the tag-team members is that prehistoric Puebloans in the Four Corners adapted to their environment for more than two centuries, but that, in the end, overpopulation overran the carrying capacity of the land.

Generations of ancestral Puebloans survived three major droughts in the Christian era - 1080 to 1100, 1130 to 1180 and 1275 to 1300 - but finally disappeared to blend into indigenous cultures that became the ancestors of modern pueblo groups, Judge said.

"They lived with a minimal ecological footprint, lived with the resources available," Judge said. "But the land couldn't support them indefinitely."

Grossman said resources are limited and since communities aren't self-contained units, it's hard to determine the maximum populations they can sustain.

"We have to look at the issues," Grossman said. "Our two major messages are that the world is changing and that climate change can have significant effect.

"Drought brought by climate change can affect our food supply. Or we could see new diseases or the return of malaria to America."

During the first prehistoric drought, the ancients who inhabitated Chaco Canyon abandoned the site for what is now Aztec because it was on the Animas River, and for the Salmon Ruins for its proximity to the San Juan River, Judge said.

"The second drought was so debilitating that the system collapsed," Judge said. "The people dispersed to many points."

In the good times that followed, populations increased, Judge said.

By the time of the third drought, the populations were overshooting the carrying capacity of the region, Judge said. Finally, the Puebloans fled the region, dispersing to the land of the Hopi, the Acoma and to the Galisteo Basin southeast of Santa Fe.

The individual ecological footprint is the amount of land required to sustain one person, Grossman said. There are four factors - living area, room to grow food, space to develop natural resources such as oil, gas or coal and somewhere to dispose of waste.

Over the entire planet, 6.7 acres are required to sustain one person, but there are only 4.4 acres available, Grossman said, citing statistics from the Global Footprint Network.

Therefore, it would require 1½ planets for the present world population, at the present rate of consumption, to live sustainably, he said.

What is notable, Grossman said, is the disparity among the number of acres needed to support one person in different countries. The United States requires 20 acres; France, 12 acres; China, 5 acres; and Haiti, 2 acres.

Judge said the message to Green Business Roundtable members is that ancestral Puebloans functioned through networking, through bottom-up, not top-down, cooperation.

The Puebloans would gather in a kiva, usually a partially underground chamber, to collectively address issues and make decisions, Grossman said.

The Green Business Roundtable could address in kiva fashion issues to promote local sustainability, Judge and Grossman said. The speakers plan to suggest what types of business could thrive in the region.

daler@durangoherald.com