Reposted from the Global Public Media.

The Neurobiology of Mass Delusion

Jason Bradford

History is replete with examples of social organizations, whether a business or a nation, that failed to perceive the realities of a changing environment and didn’t adapt in time to prevent calamity. Hubris and a self-reinforced dynamic of mass delusion characterize the waning phases of these once powerful groups. In hindsight we ask, “What were they thinking? Wasn’t the situation obvious to everyone? The evidence is so clear!” Here’s the question we should ask next: “Is history now repeating itself?”

Anyone familiar with the concepts of overshoot, resource depletion, global climate change, mass extinction, and related ills, wonders why the media, church groups and political leaders do not vigorously discuss these topics. By contrast, those unfamiliar with these issues assume that because they are not covered closely, the problems must not be too worrisome. My view is that science and history are correct, and that we are headed for a major planetary disaster as far as humans are concerned. I’ve tried to understand why the human brain, on a collective level at least, is apparently incapable of dealing with obvious problems. Here’s what I’ve learned.

For a clue to how the mind works, imagine getting startled in your own home. A shadowy figure lurking in a doorway elicits a powerful jolt to your system. It is only your spouse, of course, but it takes about half a second to realize that. This reveals what neurobiologists can now see with modern imaging techniques: visual signals get processed in more than one brain region, and the signal first arrives at the primitive hindbrain where it can respond before we are conscious of the threat. Playing runner up is the neocortex, our lumbering master of rational thought. A false alarm is inconvenient, yes, but a necessary burden. Without that startle response, a lion may have eaten us.

Emotions motivate and guide us. Fear of the lion prepares the body for fight or flight. Love binds individuals into cohesive units greater than the sum of their parts. When we succeed or fail at a task, or are praised or scorned for a particular behavior, emotional reactions are our rewards (feels good) or punishments (feels bad) and become the guideposts for our future thoughts and actions. The neocortex works with our emotions to solidify our plans. We dream about a goal and anticipate the emotional rewards of realizing it. Our self-esteem can be wrapped up in these goals and plans. They become our “mental models,” setting what is important in life and largely defining who we think we are. This is how we become determined to “stick with the program.” Mental models may range from the very short term and mundane, such as a plan to jog 12 laps, to lifetime goals and worldviews, such as a career path and religious beliefs.

Another clue about how the mind works comes from a famous experiment on the nature of the brain duality. Two films were made; both included a basketball team passing a ball among them. In one film a woman with an umbrella walks through the scene, in the other film it’s a gorilla. People were randomly shown one of the films and randomly told either to count the number of ball passes made or just watch. Now consider the mindset of the counters. They have a goal, they bind this goal to an emotional reward, and they anticipate getting the “right answer” and “feeling good.” All of those told to just watch and report anything interesting about the film recall either the woman with an umbrella or the gorilla. Over a third of those counting missed the woman and over a half missed the gorilla.

When mental models are tied to rewards, we fear and rebel against their disruption, aiming to avoid disappointment or disillusionment. Because it receives and processes sensory input faster, our emotional mind can censor from conscious awareness information that may interfere with the task required to make the goal. If a gorilla isn’t involved in actually passing the ball, then don’t pay attention to the gorilla. Depending upon circumstances, this focus can be advantageous or dangerous. If a mathematician is working on the proof of a theorem in the safety of his office that is fine, but doing so on a busy street can be deadly.

A changing environment, such as a busy street, requires us to be open to new sensory inputs and to be willing to modify or even dismiss outmoded mental models. Rigidity of mental models in the face of countervailing information is called denial. Given what we now know about the structure and function of different brain regions, we can understand the physiological roots of denial. The data nullifying a cherished mental model are systematically filtered out before the conscious brain is even aware of them. The expression, “Hear no evil, see no evil, speak no evil,” exemplifies this censoring process.

The conscious brain is not a simple dupe however. It can actively participate in the act of denial. This is termed “rationalization,” and involves complex neocortical functions. People can erect fancier houses of cards and hold on to their cherished beliefs even in the face of overwhelming contrary evidence. Many will admit that is what they are doing by resorting to the expression, “Well, I just have faith,” even when the subject is not overtly religious. This point in a discussion signals that the mental model being challenged is very important for the person, and to remove it would cause a serious and painful identity crisis. Who wants that kind of grief?

You can witness this brain duality in operation while watching debates between some of the dominant personalities of our culture, mainly those representing large financial and business interests, and the concerned watchers and interpreters of physical reality, mainly scientists in the realms of ecology, geology and climatology. Because the scientists are challenging fundamental assumptions of our culture, such as the basis for “progress” and the consequences of “economic growth,” many cannot agree with the scientists without losing their identity. This threat to the mental model is simply too great to accept. Hence you encounter two modes of response from those accepting of the prevailing paradigm: (1) the scientific data are not reliable, and (2) faith in technological progress and/or human ingenuity.

So when wondering why so many people just “don’t get it,” (oil depletion, overshoot etc.) whether they are your local politician or great aunt, realize there is a physiological mechanism that may preclude having a rational discussion on certain topics. The truth can only be pushed so far before rebellion occurs, hence the phrase, “To kill the messenger.” Before many folks can learn and incorporate the lessons of ecology, most could use the services of a good shrink. Someone to call them on their bull and get them to face their faulty, contradictory, and destructive thought patterns.

I fear that the world has neither enough shrinks nor enough time to wait for the long process of psychotherapy to work. Furthermore, enshrined institutions embody dangerous mental models within their various charters, goals and mission statements. If anyone happens to have a crisis of confidence, these institutions work to re-assimilate the disenchanted, quietly dismiss them, or destroy their reputations. Of course these are the worst possible responses. As Jared Diamond explains in his book “Collapse,” history is replete with societies that failed to question their own assumptions and create new paradigms. Instead of making life possible in a changed environment, they are part of archeology’s trash heap.

Those who know about “Peak Oil,” monetary debts, climate change, militarism, overpopulation, corporatism, soil loss, aquifer depletion, persistent organic pollutants, deforestation, etc., realize we are at a major historical juncture now. Since we know it is past time to change our culture, the question we have is whether most people will bother to listen and create the necessary transition in a rational, non-violent manner.

For those who find the terms in the previous paragraph somewhat mysterious, try this. Research the “laws of thermodynamics” and compare them to the cultural imperative for “economic growth.” See if you can recognize and then resolve the tension between the two in your mind. If you can’t resolve the tension, decide which one of these has to go. Look back at the terms in the previous paragraph and ask how they relate to what you’ve just learned. Caution: afterwards you may need a good shrink.

Jason Bradford studied tropical botany, ecology and climate change with the Missouri Botanical Garden and many colleagues around the world. Having lost faith in the ability of traditional institutions, either public or private, to deal with reality or question their own failing assumptions, he cut short his academic career to become a community organizer. He has spawned a movement to help his town face issues of resource depletion and environmental change by creating a locally sustainable economy. He resides in Willits, CA.

Reposted from the Davies & Company Website .

What are Tree Crops and Agroforestry?

Karl Davies

We think of forests as sources of fiber, and fields as sources of food.  We have the term agriculture which means the culture of fields.  And we have the term silviculture which means the culture of forests.  Since the development of scientific agriculture, there has been little overlap between agriculture and silviculture.  Nevertheless, going back further in time, particularly in pre-industrial cultures, forests were important sources of food.  Indigenous cultures all around the world still harvest much of their food from the forests.

A part of Green Hill Park in Worcester, MA which has been periodically burned by local youth, thereby approximating Native American agroforestry practices.

In the past 20 years, there has been increasing academic and practical interest in a new interdisciplinary field called agroforestry.  Agroforestry incorporates elements of forestry, agriculture and horticulture.  Traditional, indigenous agroforestry systems have been studied and improved in some cases.  This is particulary the case with tropical agroforestry systems. Temperate agrforestry systems have also been studied and improved.

One traditional practice in the Northeast that can be included under the agroforestry rubric is maple sugaring, since it produces a food product (maple products) and a fiber product (timber).  It was first developed by Native Americans and expanded by Anglo-Europeans.  It’s still a relatively important industry in some parts of the Northeast.

A large, dead standing American chestnut.  The large limb holes indicate that this tree was growing in an open pasture situation before in succumbed to the blight.

Before the demise of American chestnut forests , they were an important source of food for humans, as well as livestock that would be turned into the chestnut and oak woodlots in the fall.  This practice was commonly known as “shacking the hogs” since someone would go live in a shack where the hogs were being fattened on the chestnuts and acorns.  Of course many species of wildlife also benefited from the chestnut crops.

Around the turn of century, a new industry was emerging in Pennsylvania and New Jersey based on European chestnuts grafted to American chestnut root systems in cutover woodlots.  The grafted trees would grow rapidly and produce nuts at an early age.  Then the blight came along in the 1920s and destroyed the industry.

Black walnuts interplanted with balsam fir Christmas trees in Michigan.

Today, black walnut plantations are increasingly common in the Midwest.  Many of these are integrated with field crops such as wheat and corn.  These systems produce high quality veneer logs, nuts and annual crops.  Other agroforestry systems are being developed for riparian areas to reduce soil loss from agricultural fields, and thereby maintain water quality.  Windbreak designs are also being improved.

The Northern Nut Growers Association has been working for nearly 100 years to improve the commercial qualities of native nut trees including shagbark hickory, black walnut and butternut.  They’ve also been working with introduced species such as Chinese chestnut, Persian/Carpathian walnut, European hazel, plus hybrid Chinese-American chestnuts and European-American hazels.  Pecan is the only native North American nut to have achieved commercial success.

The American Chestnut Foundation and the American Chestnut Cooperators Foundation are working hard at restoring the American chesnut.  The former is doing this work by backcrossing American chestnuts with Chinese chestnuts to achieve a hybrid that is all American except for the Chinese genes which confer resistance to the blight.  The latter is doing their work by finding and propagating surviving American chestnuts that appear to have developed blight resistance on their own.

If you’ve ever tasted shagbark hickory nuts, you’ll appreciate the potential of this native nut.  However, the long breeding cycles needed to develop the thin shells and large kernel size necessary for commercial success are a real obstacle.  Some NNGA members have done considerable work in this direction.  The black walnut likewise has been the subject of considerable breeding.  But the strong flavor makes them suitable mainly for cooking.  Korean pine is a popular and high-priced nut that can be successfully grown in our climate.

Thinking Globally, Acting Locally. Read about my new class in Monterey, California:A Time for Healing. … This morning I feature a great essay reposted from Hope Magazine.

Positive Childishness

Lane Fisher

We´re farther down Susan´s dirt road than I´ve ever been. Only one car has passed us, but we can´t wait to leave ìcivilization” for the woods. Our steps quicken as we spot the abandoned road we want, and then we stop dead. It´s flooded.

Hopping from one high spot to another, I reach the trunk of a huge pine that a logger has left at the edge of the road. Stepping up, I pick my way across it. I am a cat. I extend my arms and stand tall. I am an Olympic gymnast. I get to the log´s end and leap clear of the massive puddle. I am a forty-three-year-old woman on an adventure with my best friend.

It was Susan´s idea to hike from her house to mine, some sixteen miles apart, without setting foot on paved roads. She wanted an adventure, something physical that we´d never done before. I agreed, eager to put my world back on a scale I understood when walking was my primary transportation. I knew shortcuts and secret worlds throughout my neighborhood during the years before I could rush from one destination to another–that is, before I got my first bike. What I don´t anticipate on this misty July morning is that I´ll also put time back in a child´s dimension, where the hands of the clock are irrelevant, and what matters are things like hunger and thirst, sunshine and shade, and whatever´s right in front of you.

JUST A SHORT DISTANCE down the abandoned road, all signs of recent logging vanish. We cross a small brook on a bridge of two granite slabs, and the road narrows. Every branch and stalk of grass that brushes our bare legs is wet, and we jump hopscotch–soil, stone, stone, soil– across more puddles. Another big one stops us, and we look over the situation. How to keep our boots dry?

ìLane, look!”

I snap my head toward Susan and follow her pointing hand. The surrounding thicket is full of red raspberries! We rush to the wet canes and eat as fast as we pick. ìMy grandma used to tell us to pick low,” says Susan, stretching toward an especially plump berry. ìI don´t know if that´s where the bigger berries are or if she just wanted to pick high without competition.” In unison we drop to a crouch and keep eating.

When we finally return to the trail, we´re beyond the puddle. Our hiking boots, shirts, and shorts are wet anyway, and long scratches adorn our legs–but our spirits have soared.

Now miles from the last house we´ve seen, we pass an old cellar hole surrounded by small yellow flowers blooming in the shade of tall oaks and pines. ìWhat do you think they´re called?” asks Susan.

ìWoodstar lilies,” I say, making it up quickly.

ìNah,” she says. ìI bet they´re dogtooth lilies.”

We feel as though we´re the first humans to be here since the forest took over that yard–even though the trail has widened into a one-lane road again. So the sight of a brand-new, red Toyota pickup parked in the woods jolts us. We crane for a glimpse of the intruder but can´t spot him.

ìWhat do you suppose that guy is doing out here on a weekday, anyway?” asks Susan uneasily.

ìI dunno. Maybe he´s wondering the same thing about ‘those two grown women,´” I answer, and we laugh.

In the next mile, camp roads begin to sprout off our trail, some marked by recent tire tracks. Then we hear a vehicle slowly coming toward us. ìIt´s him!” says Susan, and we pick up our pace, trying to keep talking as though everything is cool. As the red pickup comes alongside of us, we lift our hands in the standard Maine greeting and glance over–casually, of course. A small, white-haired man with an amused smile returns our salute and continues down the road.

At a wooden bridge, we stop for lunch, stripping off wet socks and dangling our feet over the edge. We sit at the center of a lovely, private world. A deep channel cuts through a meadow on our right; the water burbles as it drops into Sheepscot Stream below us. In the shadow of our bridge, minnows race to the crumbs we drop. It´s a quiet landscape, but it excites me: this small stream is the beginning of something I love–Sheepscot Pond, where I live, several miles to the west.

We lace up our boots and set on our way. Now on a maintained dirt road, we chatter about every part of our lives as we pass trailers, old farmhouses, and pastures.

ìI remember being really upset when I was five years old,” I tell Susan. ìI was chasing grasshoppers in the field next to our yard, feeling so relieved and happy to be out there in the sunshine but also cranky, because I wasn´t getting enough of that kind of play. I remember thinking, I never have any time anymore because I have to go to kindergarten every morning! And next year I´ll be in first grade all day long, and [my brother] Bill says there are twelve grades, so I´ll be eighteen years old before I have my time back.”

ìIt´s a good thing you didn´t know the truth of it,” says Susan.

ONCE AGAIN WE ABANDON roads for woodland trails, but there is no return to our morning´s idyll. We struggle to reconcile maps with reality. The biggest challenge is in Lake St. George State Park. Studying its black-and-white trail map is like looking at a mess of cooked spaghetti through someone else´s bifocals; my brain reels. We try a couple of trails, check our compass, and turn back. Two tanned, young park employees appear, dumping a load of brush, but they can´t make sense of the map, either. They suggest a trailhead we haven´t noticed–right behind their brush pile.

ìLet´s give it half an hour,” says Susan, ìand then decide whether to continue.” For the first time all day, I check my watch: 2:05 P.M., four hours into our hike. If we can´t find our way through the woods by late afternoon, we´ll have to head to the bottom of the park and walk walk home on Route 3, a major trunk highway. It would be ignominious defeat.

Twenty-five minutes later–all downhill –we come to a fork in the trail. On a tree hangs a board with our trail map burned into it–and color-coded! At last we know where we are: a long way from where we meant to be. We lumber back up the hill, returning to a trail we rejected earlier because it becomes a half-dry brook bed. We follow blue blazes through a stony descent into deep woods–until suddenly they end. Susan stands there while I check out nearby clearing. Yes, it´s another path. This is definitely not on our map, but it heads west, as we want to. A mountain bike track comforts us. Somebody else made it out of here.

Eventually, so do we, emerging in a backyard surrounded by scrub brush and full of chickens and old vehicles. At a bridge down the road, we meet two girls about fourteen years old and ask where we are. ìI think they call this the Arthur Plummer Road,” says one. Fantastic! Only about three miles from my home–and thirteen from where we started this morning.

Our feet are clumsy with fatigue as we trudge up another long hill. A tractor with a manure spreader passes us–the third vehicle all day to do so–and turns into a yard. The farmer calls out, ìGood day for it!” and we straighten a bit and wave.

A weary mile or two farther, we cut into the woods one last time, coming out on Route 3. Before we can cross the highway and walk a hundred feet to my driveway, five cars zoom by. We look at one another and shake our heads. Those drivers haven´t got a clue about what they´re missing.

MANY TIMES since that day, Susan and I have tried to pinpoint what made it seem charmed. Being out in nature, exploring little-known paths, and solving problems along our way–it was vastly more satisfying than our usual regimen of sitting and talking. We were so immersed in the moment that the day itself felt different: ìIt´s as though time became a wide pool in which we played, instead of something linear,” says Susan.

The eco-philosopher Joanna Macy says that if the essence of an adventure is stepping into the unknown, then the essence of a joyous adventure is not needing to know the outcome. What Susan and I rediscovered is how long and splendid a day can be when you´re out there with a sandwich, a water bottle, and a good friend, going with whatever the world serves up and knowing nothing else really matters, except getting home by dark.

Reposted from The Scientific American.

Where the Wild Things Were

A book review by Nicholas D. Kristof

Who knew that elephant trunk tastes like piglet? Or that more than a millennium ago, a writer declared that Chinese “competed to eat their trunks, the taste of which is said to be fatty and crisp, and to be particularly well suited to being roasted.”

Elephants, it turns out, once roamed across nearly all of China, as did rhinoceroses. Indeed, for 1,000 years the standard armor worn by Chinese soldiers was made from rhino hide. Yet these days rhinos are completely extinct in China, and elephants linger only in protected enclaves in the far southwest of the country.

China being China, everything has been carefully documented, so we know that these large mammals retreated gradually over the past 4,000 years, half a step ahead of smaller, two-legged ones. Mark Elvin, an Australian scholar, brilliantly uses that prolonged elephantine trail of tears as the guiding metaphor for his new book, The Retreat of the Elephants: An Environmental History of China.

Frankly, I didn’t know that I was interested in the history of Chinese elephants, or that I was yearning for an environmental history of China, until I read this book. But Elvin combines an illuminating account of the 4,000-year-long collision of humans and nature with delightful tidbits about everything under the Chinese sun.

One could not have written such an environmental history about, for instance, Britain or Russia. From China’s point of view, such countries are modern ingenues with barely any history to speak of. But in China, we hear, for example, that the Duke of Zhou, more than 3,000 years ago, drove “elephants far away” from the Yellow River valley. A record from 548 B.C. describes the ivory trade, and later we begin to get detailed accounts of battles over crops between peasants and elephants in, say, A.D. 962.

Of course, just because something has been recorded does not mean it is true. One account from 1608 reports of trained elephants in the Ming Dynasty court: “If an elephant commits an offense, or injures a human, the imperial command will be issued for him to be beaten…. Only when the beating has been concluded will he rise to his feet to give thanks for the favor received…. In the sixth lunar month they are bathed and mated. The coupling takes place in the water with a female who floats with her face upward, in all respects like a human being.” Hmmm. Floating face upward? So that’s how Ming Dynasty historians made love.

Elvin is particularly fascinating on the history of China’s long wrestling match with water. Chinese civilization may have evolved out of efforts to irrigate the land, and there is an intriguing record of the quest to tame water and land, which would typically succeed for a while until the water rebelled.

The problems were especially acute with the Yellow River, which was not called that in ancient times. Then, a little more than two millennia ago, the Qin and Han dynasties promoted farming along the upper reaches of the river, and the resulting erosion filled the water with sediment that made it muddy and gave it its present name. The sediment raised the riverbed until it was held in place only by man-made dikes that required constant attention–because the water, in essence, flowed aboveground, not below it.

Periodically dikes broke, sometimes catastrophically. A flood in 1117 is said to have killed more than one million people, making it perhaps the worst such disaster since Noah. The Yellow River dramatically changed course in 1194, moving to the south of the Shandong Peninsula, until in 1853 it moved north again. Elvin meticulously recounts China’s hydrology, so we learn, for example, that between 1195 and 1578 the Yellow River delta advanced only 39 meters a year (as sediment built up), whereas from 1579 to 1591 it advanced 1,538 meters a year.

Sometimes the sheer weight of detail is numbing, particularly in later chapters offering case studies within China. Readers without an intrinsic fascination with China may find this a book to browse, not to read cover to cover. But as a window into the history of the Middle Kingdom, and an extended account of human interactions with the environment, this is a magisterial work.

What gives this book special resonance is the impact China will have on the global environment in the coming decades. The industrial revolution in the West has been so destructive of nature that we should be wary of what the industrialization of China and India will mean. I congratulate my Chinese friends when they buy their first cars, one after the other, but collectively the result of Chinese industrialization will be to swallow up nonrenewable resources, to increase carbon emissions and presumably global warming, and to send acid rain drizzling down on much of the globe.

Yet this book does not really illuminate the road ahead. Elvin tells us that it was originally intended to carry us to the present day, but he ends up pretty much grinding to a halt a couple of hundred years ago. The even more gruesome period since–and, brace yourself, the predations still ahead of us–will have to be the subject of a companion volume. Alas, the Chinese elephants have already been driven to the country’s fringe and have nowhere else to go. And unless they figure out how to mate even when the female is not floating faceup in a pool of water, they’re really in trouble.

Copyright 2005 Scientific American

Nicholas D. Kristof is a columnist for the New York Times. He won a Pulitzer Prize for his coverage of China and is co-author, with his wife, Sheryl WuDunn, of China Wakes: The Struggle for the Soul of a Rising Power.

Reposted from the January 01, 2005 OP-ED page of The New York Times.

The Ends of the World as We Know Them

Jared Diamond

New Year’s weekend traditionally is a time for us to reflect, and to make resolutions based on our reflections. In this fresh year, with the United States seemingly at the height of its power and at the start of a new presidential term, Americans are increasingly concerned and divided about where we are going. How long can America remain ascendant? Where will we stand 10 years from now, or even next year?

Such questions seem especially appropriate this year. History warns us that when once-powerful societies collapse, they tend to do so quickly and unexpectedly. That shouldn’t come as much of a surprise: peak power usually means peak population, peak needs, and hence peak vulnerability. What can be learned from history that could help us avoid joining the ranks of those who declined swiftly? We must expect the answers to be complex, because historical reality is complex: while some societies did indeed collapse spectacularly, others have managed to thrive for thousands of years without major reversal.

When it comes to historical collapses, five groups of interacting factors have been especially important: the damage that people have inflicted on their environment; climate change; enemies; changes in friendly trading partners; and the society’s political, economic and social responses to these shifts. That’s not to say that all five causes play a role in every case. Instead, think of this as a useful checklist of factors that should be examined, but whose relative importance varies from case to case.

For instance, in the collapse of the Polynesian society on Easter Island three centuries ago, environmental problems were dominant, and climate change, enemies and trade were insignificant; however, the latter three factors played big roles in the disappearance of the medieval Norse colonies on Greenland. Let’s consider two examples of declines stemming from different mixes of causes: the falls of classic Maya civilization and of Polynesian settlements on the Pitcairn Islands.

Maya Native Americans of the Yucatan Peninsula and adjacent parts of Central America developed the New World’s most advanced civilization before Columbus. They were innovators in writing, astronomy, architecture and art. From local origins around 2,500 years ago, Maya societies rose especially after the year A.D. 250, reaching peaks of population and sophistication in the late 8th century.

Thereafter, societies in the most densely populated areas of the southern Yucatan underwent a steep political and cultural collapse: between 760 and 910, kings were overthrown, large areas were abandoned, and at least 90 percent of the population disappeared, leaving cities to become overgrown by jungle. The last known date recorded on a Maya monument by their so-called Long Count calendar corresponds to the year 909. What happened?

A major factor was environmental degradation by people: deforestation, soil erosion and water management problems, all of which resulted in less food. Those problems were exacerbated by droughts, which may have been partly caused by humans themselves through deforestation. Chronic warfare made matters worse, as more and more people fought over less and less land and resources.

Why weren’t these problems obvious to the Maya kings, who could surely see their forests vanishing and their hills becoming eroded? Part of the reason was that the kings were able to insulate themselves from problems afflicting the rest of society. By extracting wealth from commoners, they could remain well fed while everyone else was slowly starving.

What’s more, the kings were preoccupied with their own power struggles. They had to concentrate on fighting one another and keeping up their images through ostentatious displays of wealth. By insulating themselves in the short run from the problems of society, the elite merely bought themselves the privilege of being among the last to starve.

Whereas Maya societies were undone by problems of their own making, Polynesian societies on Pitcairn and Henderson Islands in the tropical Pacific Ocean were undone largely by other people’s mistakes. Pitcairn, the uninhabited island settled in 1790 by the H.M.S. Bounty mutineers, had actually been populated by Polynesians 800 years earlier. That society, which left behind temple platforms, stone and shell tools and huge garbage piles of fish and bird and turtle bones as evidence of its existence, survived for several centuries and then vanished. Why?

In many respects, Pitcairn and Henderson are tropical paradises, rich in some food sources and essential raw materials. Pitcairn is home to Southeast Polynesia’s largest quarry of stone suited for making adzes, while Henderson has the region’s largest breeding seabird colony and its only nesting beach for sea turtles. Yet the islanders depended on imports from Mangareva Island, hundreds of miles away, for canoes, crops, livestock and oyster shells for making tools.

Unfortunately for the inhabitants of Pitcairn and Henderson, their Mangarevan trading partner collapsed for reasons similar to those underlying the Maya decline: deforestation, erosion and warfare. Deprived of essential imports in a Polynesian equivalent of the 1973 oil crisis, the Pitcairn and Henderson societies declined until everybody had died or fled.

The Maya and the Henderson and Pitcairn Islanders are not alone, of course. Over the centuries, many other societies have declined, collapsed or died out. Famous victims include the Anasazi in the American Southwest, who abandoned their cities in the 12th century because of environmental problems and climate change, and the Greenland Norse, who disappeared in the 15th century because of all five interacting factors on the checklist. There were also the ancient Fertile Crescent societies, the Khmer at Angkor Wat, the Moche society of Peru – the list goes on.

But before we let ourselves get depressed, we should also remember that there is another long list of cultures that have managed to prosper for lengthy periods of time. Societies in Japan, Tonga, Tikopia, the New Guinea Highlands and Central and Northwest Europe, for example, have all found ways to sustain themselves. What separates the lost cultures from those that survived? Why did the Maya fail and the shogun succeed?

Half of the answer involves environmental differences: geography deals worse cards to some societies than to others. Many of the societies that collapsed had the misfortune to occupy dry, cold or otherwise fragile environments, while many of the long-term survivors enjoyed more robust and fertile surroundings. But it’s not the case that a congenial environment guarantees success: some societies (like the Maya) managed to ruin lush environments, while other societies – like the Incas, the Inuit, Icelanders and desert Australian Aborigines – have managed to carry on in some of the earth’s most daunting environments.

The other half of the answer involves differences in a society’s responses to problems. Ninth-century New Guinea Highland villagers, 16th-century German landowners, and the Tokugawa shoguns of 17th-century Japan all recognized the deforestation spreading around them and solved the problem, either by developing scientific reforestation (Japan and Germany) or by transplanting tree seedlings (New Guinea). Conversely, the Maya, Mangarevans and Easter Islanders failed to address their forestry problems and so collapsed.

Consider Japan. In the 1600′s, the country faced its own crisis of deforestation, paradoxically brought on by the peace and prosperity following the Tokugawa shoguns’ military triumph that ended 150 years of civil war. The subsequent explosion of Japan’s population and economy set off rampant logging for construction of palaces and cities, and for fuel and fertilizer.

The shoguns responded with both negative and positive measures. They reduced wood consumption by turning to light-timbered construction, to fuel-efficient stoves and heaters, and to coal as a source of energy. At the same time, they increased wood production by developing and carefully managing plantation forests. Both the shoguns and the Japanese peasants took a long-term view: the former expected to pass on their power to their children, and the latter expected to pass on their land. In addition, Japan’s isolation at the time made it obvious that the country would have to depend on its own resources and couldn’t meet its needs by pillaging other countries. Today, despite having the highest human population density of any large developed country, Japan is more than 70 percent forested.

There is a similar story from Iceland. When the island was first settled by the Norse around 870, its light volcanic soils presented colonists with unfamiliar challenges. They proceeded to cut down trees and stock sheep as if they were still in Norway, with its robust soils. Significant erosion ensued, carrying half of Iceland’s topsoil into the ocean within a century or two. Icelanders became the poorest people in Europe. But they gradually learned from their mistakes, over time instituting stocking limits on sheep and other strict controls, and establishing an entire government department charged with landscape management. Today, Iceland boasts the sixth-highest per-capita income in the world.

What lessons can we draw from history? The most straightforward: take environmental problems seriously. They destroyed societies in the past, and they are even more likely to do so now. If 6,000 Polynesians with stone tools were able to destroy Mangareva Island, consider what six billion people with metal tools and bulldozers are doing today. Moreover, while the Maya collapse affected just a few neighboring societies in Central America, globalization now means that any society’s problems have the potential to affect anyone else. Just think how crises in Somalia, Afghanistan and Iraq have shaped the United States today.

Other lessons involve failures of group decision-making. There are many reasons why past societies made bad decisions, and thereby failed to solve or even to perceive the problems that would eventually destroy them. One reason involves conflicts of interest, whereby one group within a society (for instance, the pig farmers who caused the worst erosion in medieval Greenland and Iceland) can profit by engaging in practices that damage the rest of society. Another is the pursuit of short-term gains at the expense of long-term survival, as when fishermen overfish the stocks on which their livelihoods ultimately depend.

History also teaches us two deeper lessons about what separates successful societies from those heading toward failure. A society contains a built-in blueprint for failure if the elite insulates itself from the consequences of its actions. That’s why Maya kings, Norse Greenlanders and Easter Island chiefs made choices that eventually undermined their societies. They themselves did not begin to feel deprived until they had irreversibly destroyed their landscape.

Could this happen in the United States? It’s a thought that often occurs to me here in Los Angeles, when I drive by gated communities, guarded by private security patrols, and filled with people who drink bottled water, depend on private pensions, and send their children to private schools. By doing these things, they lose the motivation to support the police force, the municipal water supply, Social Security and public schools. If conditions deteriorate too much for poorer people, gates will not keep the rioters out. Rioters eventually burned the palaces of Maya kings and tore down the statues of Easter Island chiefs; they have also already threatened wealthy districts in Los Angeles twice in recent decades.

In contrast, the elite in 17th-century Japan, as in modern Scandinavia and the Netherlands, could not ignore or insulate themselves from broad societal problems. For instance, the Dutch upper class for hundreds of years has been unable to insulate itself from the Netherlands’ water management problems for a simple reason: the rich live in the same drained lands below sea level as the poor. If the dikes and pumps keeping out the sea fail, the well-off Dutch know that they will drown along with everybody else, which is precisely what happened during the floods of 1953.

The other deep lesson involves a willingness to re-examine long-held core values, when conditions change and those values no longer make sense. The medieval Greenland Norse lacked such a willingness: they continued to view themselves as transplanted Norwegian pastoralists, and to despise the Inuit as pagan hunters, even after Norway stopped sending trading ships and the climate had grown too cold for a pastoral existence. They died off as a result, leaving Greenland to the Inuit. On the other hand, the British in the 1950′s faced up to the need for a painful reappraisal of their former status as rulers of a world empire set apart from Europe. They are now finding a different avenue to wealth and power, as part of a united Europe.

In this New Year, we Americans have our own painful reappraisals to face. Historically, we viewed the United States as a land of unlimited plenty, and so we practiced unrestrained consumerism, but that’s no longer viable in a world of finite resources. We can’t continue to deplete our own resources as well as those of much of the rest of the world.

Historically, oceans protected us from external threats; we stepped back from our isolationism only temporarily during the crises of two world wars. Now, technology and global interconnectedness have robbed us of our protection. In recent years, we have responded to foreign threats largely by seeking short-term military solutions at the last minute.

But how long can we keep this up? Though we are the richest nation on earth, there’s simply no way we can afford (or muster the troops) to intervene in the dozens of countries where emerging threats lurk – particularly when each intervention these days can cost more than $100 billion and require more than 100,000 troops.

A genuine reappraisal would require us to recognize that it will be far less expensive and far more effective to address the underlying problems of public health, population and environment that ultimately cause threats to us to emerge in poor countries. In the past, we have regarded foreign aid as either charity or as buying support; now, it’s an act of self-interest to preserve our own economy and protect American lives.

Do we have cause for hope? Many of my friends are pessimistic when they contemplate the world’s growing population and human demands colliding with shrinking resources. But I draw hope from the knowledge that humanity’s biggest problems today are ones entirely of our own making. Asteroids hurtling at us beyond our control don’t figure high on our list of imminent dangers. To save ourselves, we don’t need new technology: we just need the political will to face up to our problems of population and the environment.

I also draw hope from a unique advantage that we enjoy. Unlike any previous society in history, our global society today is the first with the opportunity to learn from the mistakes of societies remote from us in space and in time. When the Maya and Mangarevans were cutting down their trees, there were no historians or archaeologists, no newspapers or television, to warn them of the consequences of their actions. We, on the other hand, have a detailed chronicle of human successes and failures at our disposal. Will we choose to use it?

Copyright 2005 The New York Times Company

Jared Diamond, who won the 1998 Pulitzer Prize in general nonfiction for “Guns, Germs and Steel: The Fates of Human Societies,”is the author of the forthcoming “Collapse: How Societies Choose or Fail to Succeed.”