Natural History essay – our fate

Natural History in one essay:



The State Of   The Species, By Charles C. Mann





Reposted from ORION MAGAZINE


The problem   with environmentalists, Lynn Margulis used to say, is that they think   conservation has something to do with biological reality. A researcher who   specialized in cells and microorganisms, Margulis was one of the most   important biologists in the last half century—she literally helped to reorder   the tree of life, convincing her colleagues that it did not consist of two   kingdoms (plants and animals), but five or even six (plants, animals, fungi,   protists, and two types of bacteria).

Until   Margulis’s death last year, she lived in my town, and I would bump into her   on the street from time to time. She knew I was interested in ecology, and   she liked to needle me. Hey, Charles, she would call out,   are you still all worked up about protecting endangered species?

Margulis was   no apologist for unthinking destruction. Still, she couldn’t help regarding   conservationists’ preoccupation with the fate of birds, mammals, and plants   as evidence of their ignorance about the greatest source of evolutionary   creativity: the microworld of bacteria, fungi, and protists. More than 90   percent of the living matter on earth consists of microorganisms and viruses,   she liked to point out. Heck, the number of bacterial cells in our body is   ten times more than the number of human cells!

Bacteria and   protists can do things undreamed of by clumsy mammals like us: form giant   supercolonies, reproduce either asexually or by swapping genes with others,   routinely incorporate DNA from entirely unrelated species, merge into   symbiotic beings—the list is as endless as it is amazing. Microorganisms have   changed the face of the earth, crumbling stone and even giving rise to the   oxygen we breathe. Compared to this power and diversity, Margulis liked to   tell me, pandas and polar bears were biological epiphenomena—interesting and   fun, perhaps, but not actuallysignificant.

Does that   apply to human beings, too? I once asked her, feeling like someone whining to   Copernicus about why he couldn’t move the earth a little closer to the center   of the universe. Aren’t we specialat all?

This was just   chitchat on the street, so I didn’t write anything down. But as I recall it,   she answered that Homo sapiens actually might be   interesting—for a mammal, anyway. For one thing, she said, we’re unusually   successful.

Seeing my   face brighten, she added: Of course, the fate of every successful species is   to wipe itself out.



Why and how   did humankind become “unusually successful”? And what, to an evolutionary   biologist, does “success” mean, if self-destruction is part of the   definition? Does that self-destruction include the rest of the biosphere?   What are human beings in the grand scheme of things anyway, and where are we   headed? What is human nature, if there is such a thing, and how did we   acquire it? What does that nature portend for our interactions with the   environment? With 7 billion of us crowding the planet, it’s hard to imagine   more vital questions.

One way to   begin answering them came to Mark Stoneking in 1999, when he received a   notice from his son’s school warning of a potential lice outbreak in the   classroom. Stoneking is a researcher at the Max Planck Institute for   Evolutionary Biology in Leipzig, Germany. He didn’t know much about lice. As   a biologist, it was natural for him to noodle around for information about   them. The most common louse found on human bodies, he discovered, is Pediculus   humanus. P. humanus has two subspecies: P. humanus capitis—head   lice, which feed and live on the scalp—and P. humanus corporis—body   lice, which feed on skin but live in clothing. In fact, Stoneking learned,   body lice are so dependent on the protection of clothing that they cannot   survive more than a few hours away from it.

It occurred   to him that the two louse subspecies could be used as an evolutionary   probe. P. humanus capitis, the head louse, could be an   ancient annoyance, because human beings have always had hair for it to   infest. But P. humanus corporis, the body louse, must not be   especially old, because its need for clothing meant that it could not have   existed while humans went naked. Humankind’s great coverup had created a new   ecological niche, and some head lice had rushed to fill it. Evolution then   worked its magic; a new subspecies,P. humanus corporis, arose.   Stoneking couldn’t be sure that this scenario had taken place, though it   seemed likely. But if his idea were correct, discovering when the body louse   diverged from the head louse would provide a rough date for when people first   invented and wore clothing.

The subject   was anything but frivolous: donning a garment is a complicated act. Clothing   has practical uses—warming the body in cold places, shielding it from the sun   in hot places—but it also transforms the appearance of the wearer, something   that has proven to be of inescapable interest to Homo sapiens. Clothing   is ornament and emblem; it separates human beings from their earlier,   un-self-conscious state. (Animals run, swim, and fly without clothing, but   only people can be naked.) The invention of clothing was a sign   that a mental shift had occurred. The human world had become a realm of   complex, symbolic artifacts.

With two   colleagues, Stoneking measured the difference between snippets of DNA in the   two louse subspecies. Because DNA is thought to pick up small, random   mutations at a roughly constant rate, scientists use the number of   differences between two populations to tell how long ago they diverged from a   common ancestor—the greater the number of differences, the longer the   separation. In this case, the body louse had separated from the head louse   about 70,000 years ago. Which meant, Stoneking hypothesized, that clothing   also dated from about 70,000 years ago.

And not just   clothing. As scientists have established, a host of remarkable things   occurred to our species at about that time. It marked a dividing line in our   history, one that made us who we are, and pointed us, for better and worse,   toward the world we now have created for ourselves.

Homo   sapiens emerged on the   planet about 200,000 years ago, researchers believe. From the beginning, our   species looked much as it does today. If some of those long-ago people walked   by us on the street now, we would think they looked and acted somewhat oddly,   but not that they weren’t people. But those anatomically modern   humans were not, as anthropologists say, behaviorally modern.   Those first people had no language, no clothing, no art, no religion, nothing   but the simplest, unspecialized tools. They were little more advanced,   technologically speaking, than their predecessors—or, for that matter, modern   chimpanzees. (The big exception was fire, but that was first controlled by Homo   erectus, one of our ancestors, a million years ago or more.) Our   species had so little capacity for innovation that archaeologists have found   almost no evidence of cultural or social change during our first 100,000   years of existence. Equally important, for almost all that time these early   humans were confined to a single, small area in the hot, dry savanna of East   Africa (and possibly a second, still smaller area in southern Africa).

But now jump   forward 50,000 years. East Africa looks much the same. So do the humans in   it—but suddenly they are drawing and carving images, weaving ropes and   baskets, shaping and wielding specialized tools, burying the dead in formal   ceremonies, and perhaps worshipping supernatural beings. They are wearing   clothes—lice-filled clothes, to be sure, but clothes nonetheless.   Momentously, they are using language. And they are dramatically increasing   their range. Homo sapiens is exploding across the planet.

What caused   this remarkable change? By geologists’ standards, 50,000 years is an instant,   a finger snap, a rounding error. Nonetheless, most researchers believe that   in that flicker of time, favorable mutations swept through our species,   transforming anatomically modern humans into behaviorally modern humans. The   idea is not absurd: in the last 400 years, dog breeders converted village   dogs into creatures that act as differently as foxhounds, border collies, and   Labrador retrievers. Fifty millennia, researchers say, is more than enough to   make over a species.

Homo   sapiens lacks claws,   fangs, or exoskeletal plates. Rather, our unique survival skill is our   ability to innovate, which originates with our species’ singular brain—a   three-pound universe of hyperconnected neural tissue, constantly aswirl with   schemes and notions. Hence every hypothesized cause for the transformation of   humankind from anatomically modern to behaviorally modern involves a physical   alteration of the wet gray matter within our skulls. One candidate   explanation is that in this period people developed hybrid mental abilities   by interbreeding with Neanderthals. (Some Neanderthal genes indeed appear to   be in our genome, though nobody is yet certain of their function.) Another   putative cause is symbolic language—an invention that may have tapped latent   creativity and aggressiveness in our species. A third is that a mutation   might have enabled our brains to alternate between spacing out on imaginative   chains of association and focusing our attention narrowly on the physical   world around us. The former, in this view, allows us to come up with creative   new strategies to achieve a goal, whereas the latter enables us to execute   the concrete tactics required by those strategies.

Each of these   ideas is fervently advocated by some researchers and fervently attacked by   others. What is clear is that something made over our   species between 100,000 and 50,000 years ago—and right in the middle of that   period was Toba.



About 75,000   years ago, a huge volcano exploded on the island of Sumatra. The biggest   blast for several million years, the eruption created Lake Toba, the world’s   biggest crater lake, and ejected the equivalent of as much as 3,000 cubic   kilometers of rock, enough to cover the District of Columbia in a layer of   magma and ash that would reach to the stratosphere. A gigantic plume spread   west, enveloping southern Asia in tephra (rock, ash, and dust). Drifts in   Pakistan and India reached as high as six meters. Smaller tephra beds   blanketed the Middle East and East Africa. Great rafts of pumice filled the   sea and drifted almost to Antarctica.

In the long   run, the eruption raised Asian soil fertility. In the short term, it was   catastrophic. Dust hid the sun for as much as a decade, plunging the earth   into a years-long winter accompanied by widespread drought. A vegetation   collapse was followed by a collapse in the species that depended on   vegetation, followed by a collapse in the species that depended on the   species that depended on vegetation. Temperatures may have remained colder   than normal for a thousand years. Orangutans, tigers, chimpanzees,   cheetahs—all were pushed to the verge of extinction.

At about this   time, many geneticists believe, Homo sapiens’ numbers shrank   dramatically, perhaps to a few thousand people—the size of a big urban high   school. The clearest evidence of this bottleneck is also its main legacy:   humankind’s remarkable genetic uniformity. Countless people have viewed the   differences between races as worth killing for, but compared to other   primates—even compared to most other mammals—human beings are almost   indistinguishable, genetically speaking. DNA is made from exceedingly long   chains of “bases.” Typically, about one out of every 2,000 of these “bases”   differs between one person and the next. The equivalent figure from two E.   coli (human gut bacteria) might be about one out of twenty. The   bacteria in our intestines, that is, have a hundredfold more innate   variability than their hosts—evidence, researchers say, that our species is   descended from a small group of founders.

Uniformity is   hardly the only effect of a bottleneck. When a species shrinks in number,   mutations can spread through the entire population with astonishing rapidity.   Or genetic variants that may have already been in existence—arrays of genes   that confer better planning skills, for example—can suddenly become more   common, effectively reshaping the species within a few generations as   once-unusual traits become widespread.

Did Toba, as   theorists like Richard Dawkins have argued, cause an evolutionary bottleneck   that set off the creation of behaviorally modern people, perhaps by helping   previously rare genes—Neanderthal DNA or an opportune mutation—spread through   our species? Or did the volcanic blast simply clear away other human species   that had previously blocked H. sapiens’ expansion? Or was   the volcano irrelevant to the deeper story of human change?

For now, the   answers are the subject of careful back-and-forth in refereed journals and   heated argument in faculty lounges. All that is clear is that about the time   of Toba, new, behaviorally modern people charged so fast into the tephra that   human footprints appeared in Australia within as few as 10,000 years, perhaps   within 4,000 or 5,000. Stay-at-home Homo sapiens 1.0, a   wallflower that would never have interested Lynn Margulis, had been replaced   by aggressively expansive Homo sapiens 2.0. Something   happened, for better and worse, and we were born.

One way to   illustrate what this upgrade looked like is to considerSolenopsis invicta, the   red imported fire ant. Geneticists believe thatS. invicta originated   in northern Argentina, an area with many rivers and frequent floods. The   floods wipe out ant nests. Over the millennia, these small, furiously active   creatures have acquired the ability to respond to rising water by coalescing   into huge, floating, pullulating balls—workers on the outside, queen in the   center—that drift to the edge of the flood. Once the waters recede, colonies   swarm back into previously flooded land so rapidly that S. invictaactually   can use the devastation to increase its range.

In the   1930s, Solenopsis invicta was transported to the United   States, probably in ship ballast, which often consists of haphazardly loaded   soil and gravel. As a teenaged bug enthusiast, Edward O. Wilson, the famed   biologist, spotted the first colonies in the port of Mobile, Alabama. He saw   some very happy fire ants. From the ant’s point of view, it had been dumped   into an empty, recently flooded expanse. S. invicta took   off, never looking back.

The initial   incursion watched by Wilson was likely just a few thousand individuals—a   number small enough to suggest that random, bottleneck-style genetic change   played a role in the species’ subsequent history in this country. In their   Argentine birthplace, fire-ant colonies constantly fight each other, reducing   their numbers and creating space for other types of ant. In the United   States, by contrast, the species forms cooperative supercolonies, linked   clusters of nests that can spread for hundreds of miles. Systematically   exploiting the landscape, these supercolonies monopolize every useful   resource, wiping out other ant species along the way—models of zeal and   rapacity. Transformed by chance and opportunity, new-model S.   invictus needed just a few decades to conquer most of the southern   United States.

Homo   sapiens did something   similar in the wake of Toba. For hundreds of thousands of years, our species   had been restricted to East Africa (and, possibly, a similar area in the   south). Now, abruptly, new-model Homo sapiens were racing   across the continents like so many imported fire ants. The difference between   humans and fire ants is that fire ants specialize in disturbed habitats.   Humans, too, specialize in disturbed habitats—but we do the disturbing.



As a student   at the University of Moscow in the 1920s, Georgii Gause spent years   trying—and failing—to drum up support from the Rockefeller Foundation, then   the most prominent funding source for non-American scientists who wished to   work in the United States. Hoping to dazzle the foundation, Gause decided to   perform some nifty experiments and describe the results in his grant   application.

By today’s   standards, his methodology was simplicity itself. Gause placed half a gram of   oatmeal in one hundred cubic centimeters of water, boiled the results for ten   minutes to create a broth, strained the liquid portion of the broth into a   container, diluted the mixture by adding water, and then decanted the   contents into small, flat-bottomed test tubes. Into each he dripped   five Paramecium caudatum or Stylonychia mytilus, both   single-celled protozoans, one species per tube. Each of Gause’s test tubes   was a pocket ecosystem, a food web with a single node. He stored the tubes in   warm places for a week and observed the results. He set down his conclusions   in a 163-page book, The Struggle for Existence,published in 1934.

Today The   Struggle for Existence is recognized as a scientific landmark, one   of the first successful marriages of theory and experiment in ecology. But   the book was not enough to get Gause a fellowship; the Rockefeller Foundation   turned down the twenty-four-year-old Soviet student as insufficiently   eminent. Gause could not visit the United States for another twenty years, by   which time he had indeed become eminent, but as an antibiotics researcher.

What Gause   saw in his test tubes is often depicted in a graph, time on the horizontal   axis, the number of protozoa on the vertical. The line on the graph is a   distorted bell curve, with its left side twisted and stretched into a kind of   flattened S. At first the number of protozoans grows slowly, and the graph   line slowly ascends to the right. But then the line hits an inflection point,   and suddenly rockets upward—a frenzy of exponential growth. The mad rise   continues until the organism begins to run out of food, at which point there   is a second inflection point, and the growth curve levels off again as   bacteria begin to die. Eventually the line descends, and the population falls   toward zero.

Years ago I   watched Lynn Margulis, one of Gause’s successors, demonstrate these   conclusions to a class at the University of Massachusetts with a time-lapse   video of Proteus vulgaris, a bacterium that lives in the   gastrointestinal tract. To humans, she said, P. vulgaris is   mainly notable as a cause of urinary-tract infections. Left alone, it divides   about every fifteen minutes. Margulis switched on the projector. Onscreen was   a small, wobbly bubble—P. vulgaris—in a shallow, circular glass   container: a petri dish. The class gasped. The cells in the time-lapse video   seemed to shiver and boil, doubling in number every few seconds, colonies   exploding out until the mass of bacteria filled the screen. In just   thirty-six hours, she said, this single bacterium could cover the entire   planet in a foot-deep layer of single-celled ooze. Twelve hours after that,   it would create a living ball of bacteria the size of the earth.

Such a   calamity never happens, because competing organisms and lack of resources   prevent the overwhelming majority of P. vulgarisfrom reproducing.   This, Margulis said, is natural selection, Darwin’s great insight. All living   creatures have the same purpose: to make more of themselves, ensuring their   biological future by the only means available. Natural selection stands in   the way of this goal. It prunes back almost all species, restricting their   numbers and confining their range. In the human body, P. vulgaris is   checked by the size of its habitat (portions of the human gut), the limits to   its supply of nourishment (food proteins), and other, competing organisms.   Thus constrained, its population remains roughly steady.

In the petri   dish, by contrast, competition is absent; nutrients and habitat seem   limitless, at least at first. The bacterium hits the first inflection point   and rockets up the left side of the curve, swamping the petri dish in a   reproductive frenzy. But then its colonies slam into the second inflection   point: the edge of the dish. When the dish’s nutrient supply is   exhausted, P. vulgaris experiences a miniapocalypse.

By luck or   superior adaptation, a few species manage to escape their limits, at least   for a while. Nature’s success stories, they are like Gause’s protozoans; the   world is their petri dish. Their populations grow exponentially; they take over   large areas, overwhelming their environment as if no force opposed them. Then   they annihilate themselves, drowning in their own wastes or starving from   lack of food.

To someone   like Margulis, Homo sapiens looks like one of these briefly   fortunate species.



No more than   a few hundred people initially migrated from Africa, if geneticists are   correct. But they emerged into landscapes that by today’s standards were as   rich as Eden. Cool mountains, tropical wetlands, lush forests—all were teeming   with food. Fish in the sea, birds in the air, fruit on the trees: breakfast   was everywhere. People moved in.

Despite our   territorial expansion, though, humans were still only in the initial stages   of Gause’s oddly shaped curve. Ten thousand years ago, most demographers   believe, we numbered barely 5 million, about one human being for every   hundred square kilometers of the earth’s land surface. Homo sapiens was   a scarcely noticeable dusting on the surface of a planet dominated by   microbes. Nevertheless, at about this time—10,000 years ago, give or take a   millennium—humankind finally began to approach the first inflection point.   Our species was inventing agriculture.

The wild   ancestors of cereal crops like wheat, barley, rice, and sorghum have been   part of the human diet for almost as long as there have been humans to eat   them. (The earliest evidence comes from Mozambique, where researchers found   tiny bits of 105,000-year-old sorghum on ancient scrapers and grinders.) In   some cases people may have watched over patches of wild grain, returning to   them year after year. Yet despite the effort and care the plants were not   domesticated. As botanists say, wild cereals “shatter”—individual grain   kernels fall off as they ripen, scattering grain haphazardly, making it   impossible to harvest the plants systematically. Only when unknown geniuses   discovered naturally mutated grain plants that did not shatter—and   purposefully selected, protected, and cultivated them—did true agriculture   begin. Planting great expanses of those mutated crops, first in southern   Turkey, later in half a dozen other places, early farmers created landscapes   that, so to speak, waited for hands to harvest them.

Farming   converted most of the habitable world into a petri dish. Foragers manipulated   their environment with fire, burning areas to kill insects and encourage the   growth of useful species—plants we liked to eat, plants that attracted the   other creatures we liked to eat. Nonetheless, their diets were largely   restricted to what nature happened to provide in any given time and season.   Agriculture gave humanity the whip hand. Instead of natural ecosystems with   their haphazard mix of species (so many useless organisms guzzling up   resources!), farms are taut, disciplined communities conceived and dedicated   to the maintenance of a single species: us.

Before   agriculture, the Ukraine, American Midwest, and lower Yangzi were barely   hospitable food deserts, sparsely inhabited landscapes of insects and grass;   they became breadbaskets as people scythed away suites of species that used   soil and water we wanted to dominate and replaced them with wheat, rice, and   maize (corn). To one of Margulis’s beloved bacteria, a petri dish is a   uniform expanse of nutrients, all of which it can seize and consume.   For Homo sapiens, agriculture transformed the planet into   something similar.

As in a   time-lapse movie, we divided and multiplied across the newly opened land. It   had taken Homo sapiens 2.0, behaviorally modern humans, not   even 50,000 years to reach the farthest corners of the globe. Homo   sapiens 2.0.A—A for agriculture—took a tenth of that time to conquer   the planet.

As any   biologist would predict, success led to an increase in human numbers. Homo   sapiens rocketed around the elbow of the first inflection point in   the seventeenth and eighteenth centuries, when American crops like potatoes,   sweet potatoes, and maize were introduced to the rest of the world.   Traditional Eurasian and African cereals—wheat, rice, millet, and sorghum,   for example—produce their grain atop thin stalks. Basic physics suggests that   plants with this design will fatally topple if the grain gets too heavy,   which means that farmers can actually be punished if they have an   extra-bounteous harvest. By contrast, potatoes and sweet potatoes grow   underground, which means that yields are not limited by the plant’s   architecture. Wheat farmers in Edinburgh and rice farmers in Edo alike   discovered they could harvest four times as much dry food matter from an acre   of tubers than they could from an acre of cereals. Maize, too, was a winner.   Compared to other cereals, it has an extra-thick stalk and a different, more   productive type of photosynthesis. Taken together, these immigrant crops   vastly increased the food supply in Europe, Asia, and Africa, which in turn helped   increase the supply of Europeans, Asians, and Africans. The population boom   had begun.

Numbers kept   rising in the nineteenth and twentieth centuries, after a German chemist,   Justus von Liebig, discovered that plant growth was limited by the supply of   nitrogen. Without nitrogen, neither plants nor the mammals that eat plants   can create proteins, or for that matter the DNA and RNA that direct their   production. Pure nitrogen gas (N2) is plentiful in the air but plants are   unable to absorb it, because the two nitrogen atoms in N2 are welded so   tightly together that plants cannot split them apart for use. Instead, plants   take in nitrogen only when it is combined with hydrogen, oxygen, and other   elements. To restore exhausted soil, traditional farmers grew peas, beans,   lentils, and other pulses. (They never knew why these “green   manures” replenished the land. Today we know that their roots contain special   bacteria that convert useless N2 into “bio-available” nitrogen compounds.)   After Liebig, European and American growers replaced those crops with   high-intensity fertilizer—nitrogen-rich guano from Peru at first, then   nitrates from mines in Chile. Yields soared. But supplies were much more   limited than farmers liked. So intense was the competition for fertilizer   that a guano war erupted in 1879, engulfing much of western South America.   Almost 3,000 people died.

Two more   German chemists, Fritz Haber and Carl Bosch, came to the rescue, discovering   the key steps to making synthetic fertilizer from fossil fuels. (The process   involves combining nitrogen gas and hydrogen from natural gas into ammonia,   which is then used to create nitrogenous compounds usable by plants.) Haber   and Bosch are not nearly as well known as they should be; their discovery,   the Haber-Bosch process, has literally changed the chemical composition of   the earth, a feat previously reserved for microorganisms. Farmers have   injected so much synthetic fertilizer into the soil that soil and groundwater   nitrogen levels have risen worldwide. Today, roughly a third of all the   protein (animal and vegetable) consumed by humankind is derived from   synthetic nitrogen fertilizer. Another way of putting this is to say that   Haber and Bosch enabled Homo sapiensto extract about 2 billion   people’s worth of food from the same amount of available land.

The improved   wheat, rice, and (to a lesser extent) maize varieties developed by plant   breeders in the 1950s and 1960s are often said to have prevented another   billion deaths. Antibiotics, vaccines, and water-treatment plants also saved   lives by pushing back humankind’s bacterial, viral, and fungal enemies. With   almost no surviving biological competition, humankind had ever more   unhindered access to the planetary petri dish: in the past two hundred years,   the number of humans walking the planet ballooned from 1 to 7 billion, with a   few billion more expected in coming decades.

Rocketing up   the growth curve, human beings “now appropriate nearly 40% . . . of potential   terrestrial productivity.” This figure dates from 1986—a famous estimate by a   team of Stanford biologists. Ten years later, a second Stanford team   calculated that the “fraction of the land’s biological production that is   used or dominated” by our species had risen to as much as 50 percent. In   2000, the chemist Paul Crutzen gave a name to our time: the “Anthropocene,”   the era in which Homo sapiens became a force operating on a   planetary scale. That year, half of the world’s accessible fresh water was   consumed by human beings.

Lynn   Margulis, it seems safe to say, would have scoffed at these assessments of   human domination over the natural world, which, in every case I know of, do   not take into account the enormous impact of the microworld. But she would   not have disputed the central idea:Homo sapiens has become a   successful species, and is growing accordingly.

If we follow   Gause’s pattern, growth will continue at a delirious speed until we hit the   second inflection point. At that time we will have exhausted the resources of   the global petri dish, or effectively made the atmosphere toxic with our   carbon-dioxide waste, or both. After that, human life will be, briefly, a   Hobbesian nightmare, the living overwhelmed by the dead. When the king falls,   so do his minions; it is possible that our fall might also take down most mammals   and many plants. Possibly sooner, quite likely later, in this scenario, the   earth will again be a choir of bacteria, fungi, and insects, as it has been   through most of its history.

It would be   foolish to expect anything else, Margulis thought. More than that, it would   be unnatural.



In The   Phantom Tollbooth, Norton Juster’s classic, pun-filled adventure   tale, the young Milo and his faithful companions unexpectedly find themselves   transported to a bleak, mysterious island. Encountering a man in a tweed   jacket and beanie, Milo asks him where they are. The man replies by asking if   they know who he is—the man is, apparently, confused on the subject. Milo and   his friends confer, then ask if he can describe himself.

“Yes,   indeed,” the man replied happily. “I’m as tall as can be”—and he grew   straight up until all that could be seen of him were his shoes and   stockings—“and I’m as short as can be”—and he shrank down to the size of a   pebble. “I’m as generous as can be,” he said, handing each of them a large   red apple, “and I’m as selfish as can be,” he snarled, grabbing them back   again.

In short   order, the companions learn that the man is as strong as can be, weak as can   be, smart as can be, stupid as can be, graceful as can be, clumsy as—you get   the picture. “Is that any help to you?” he asks. Again, Milo and his friends   confer, and realize that the answer is actually quite simple:

“Without a   doubt,” Milo concluded brightly, “you must be Canby.”

“Of   course, yes, of course,” the man shouted. “Why didn’t I think of that? I’m as   happy as can be.”

With Canby,   Juster presumably meant to mock a certain kind of babyish, uncommitted   man-child. But I can’t help thinking of poor old Canby as exemplifying one of   humankind’s greatest attributes:behavioral plasticity. The term   was coined in 1890 by the pioneering psychologist William James, who defined   it as “the possession of a structure weak enough to yield to an influence,   but strong enough not to yield all at once.” Behavioral plasticity, a   defining feature ofHomo sapiens’ big brain, means that humans can   change their habits; almost as a matter of course, people change careers,   quit smoking or take up vegetarianism, convert to new religions, and migrate   to distant lands where they must learn strange languages. This plasticity,   this Canby-hood, is the hallmark of our transformation from anatomically   modern Homo sapiens to behaviorally modern Homo   sapiens—and the reason, perhaps, we were able to survive when Toba   reconfigured the landscape.

Other   creatures are much less flexible. Like apartment-dwelling cats that   compulsively hide in the closet when visitors arrive, they have limited   capacity to welcome new phenomena and change in response. Human beings, by   contrast, are so exceptionally plastic that vast swaths of neuroscience are   devoted to trying to explain how this could come about. (Nobody knows for   certain, but some researchers now think that particular genes give their   possessors a heightened, inborn awareness of their environment, which can   lead both to useless, neurotic sensitivity and greater ability to detect and   adapt to new situations.)

Plasticity in   individuals is mirrored by plasticity on a societal level. The caste system   in social species like honeybees is elaborate and finely tuned but fixed, as   if in amber, in the loops of their DNA. Some leafcutter ants are said to   have, next to human beings, the biggest and most complex societies on earth,   with elaborately coded behavior that reaches from disposal of the dead to   complex agricultural systems. Housing millions of individuals in   inconceivably ramose subterranean networks, leafcutter colonies are “Earth’s   ultimate superorganisms,” Edward O. Wilson has written. But they are   incapable of fundamental change. The centrality and authority of the queen cannot   be challenged; the tiny minority of males, used only to inseminate queens,   will never acquire new responsibilities.

Human   societies are far more varied than their insect cousins, of course. But the   true difference is their plasticity. It is why humankind, a species of   Canbys, has been able to move into every corner of the earth, and to control   what we find there. Our ability to change ourselves to extract resources from   our surroundings with ever-increasing efficiency is what has made Homo   sapiens a successful species. It is our greatest blessing.

Or was our   greatest blessing, anyway.



By 2050,   demographers predict, as many as 10 billion human beings will walk the earth,   3 billion more than today. Not only will more people exist than ever before,   they will be richer than ever before. In the last three decades hundreds of   millions in China, India, and other formerly poor places have lifted   themselves from destitution—arguably the most important, and certainly the   most heartening, accomplishment of our time. Yet, like all human enterprises,   this great success will pose great difficulties.

In the past,   rising incomes have invariably prompted rising demand for goods and services.   Billions more jobs, homes, cars, fancy electronics—these are things the newly   prosperous will want. (Why shouldn’t they?) But the greatest challenge may be   the most basic of all: feeding these extra mouths. To agronomists, the   prospect is sobering. The newly affluent will not want their ancestors’   gruel. Instead they will ask for pork and beef and lamb. Salmon will sizzle   on their outdoor grills. In winter, they will want strawberries, like people   in New York and London, and clean bibb lettuce from hydroponic gardens.

All of these,   each and every one, require vastly more resources to produce than simple   peasant agriculture. Already 35 percent of the world’s grain harvest is used   to feed livestock. The process is terribly inefficient: between seven and ten   kilograms of grain are required to produce one kilogram of beef. Not only   will the world’s farmers have to produce enough wheat and maize to feed 3   billion more people, they will have to produce enough to give them all   hamburgers and steaks. Given present patterns of food consumption, economists   believe, we will need to produce about 40 percent more grain in 2050 than we   do today.

How can we   provide these things for all these new people? That is only part of the   question. The full question is: How can we provide them without wrecking the   natural systems on which all depend?

Scientists,   activists, and politicians have proposed many solutions, each from a   different ideological and moral perspective. Some argue that we must   drastically throttle industrial civilization. (Stop energy-intensive,   chemical-based farming today! Eliminate fossil fuels to halt climate change!)   Others claim that only intense exploitation of scientific knowledge can save   us. (Plant super-productive, genetically modified crops now! Switch to   nuclear power to halt climate change!) No matter which course is chosen,   though, it will require radical, large-scale transformations in the human   enterprise—a daunting, hideously expensive task.

Worse, the   ship is too large to turn quickly. The world’s food supply cannot be   decoupled rapidly from industrial agriculture, if that is seen as the answer.   Aquifers cannot be recharged with a snap of the fingers. If the high-tech   route is chosen, genetically modified crops cannot be bred and tested   overnight. Similarly, carbon-sequestration techniques and nuclear power plants   cannot be deployed instantly. Changes must be planned and executed decades in   advance of the usual signals of crisis, but that’s like asking healthy, happy   sixteen-year-olds to write living wills.

Not only is   the task daunting, it’s strange. In the name of nature, we   are asking human beings to do something deeply unnatural, something no other   species has ever done or could ever do: constrain its own growth (at least in   some ways). Zebra mussels in the Great Lakes, brown tree snakes in Guam,   water hyacinth in African rivers, gypsy moths in the northeastern U.S.,   rabbits in Australia, Burmese pythons in Florida—all these successful species   have overrun their environments, heedlessly wiping out other creatures. Like   Gause’s protozoans, they are racing to find the edges of their petri dish.   Not one has voluntarily turned back. Now we are asking Homo sapiens to   fence itself in.

What a   peculiar thing to ask! Economists like to talk about the “discount rate,”   which is their term for preferring a bird in hand today over two in the bush   tomorrow. The term sums up part of our human nature as well. Evolving in   small, constantly moving bands, we are as hard-wired to focus on the   immediate and local over the long-term and faraway as we are to prefer   parklike savannas to deep dark forests. Thus, we care more about the broken   stoplight up the street today than conditions next year in Croatia, Cambodia,   or the Congo. Rightly so, evolutionists point out: Americans are far more   likely to be killed at that stoplight today than in the Congo next year. Yet   here we are asking governments to focus on potential planetary boundaries   that may not be reached for decades. Given the discount rate, nothing could   be more understandable than the U.S. Congress’s failure to grapple with, say,   climate change. From this perspective, is there any reason to imagine   that Homo sapiens,unlike mussels, snakes, and moths, can exempt   itself from the natural fate of all successful species?

To biologists   like Margulis, who spend their careers arguing that humans are simply part of   the natural order, the answer should be clear. All life is similar at base.   All species seek without pause to make more of themselves—that is their goal.   By multiplying till we reach our maximum possible numbers, even as we take out   much of the planet, we are fulfilling our destiny.

From this   vantage, the answer to the question whether we are doomed to destroy   ourselves is yes. It should be obvious.

Should be—but perhaps is not.



When I   imagine the profound social transformation necessary to avoid calamity, I   think about Robinson Crusoe, hero of Daniel Defoe’s famous novel. Defoe   clearly intended his hero to be an exemplary man. Shipwrecked on an   uninhabited island off Venezuela in 1659, Crusoe is an impressive example of   behavioral plasticity. During his twenty-seven-year exile he learns to catch   fish, hunt rabbits and turtles, tame and pasture island goats, prune and   support local citrus trees, and create “plantations” of barley and rice from   seeds that he salvaged from the wreck. (Defoe apparently didn’t know that   citrus and goats were not native to the Americas and thus Crusoe probably   wouldn’t have found them there.) Rescue comes at last in the form of a   shipful of ragged mutineers, who plan to maroon their captain on the   supposedly empty island. Crusoe helps the captain recapture his ship and   offers the defeated mutineers a choice: trial in England or permanent   banishment to the island. All choose the latter. Crusoe has harnessed so much   of the island’s productive power to human use that even a gaggle of inept   seamen can survive there in comfort.

To get Crusoe   on his unlucky voyage, Defoe made him an officer on a slave ship,   transporting captured Africans to South America. Today, no writer would make   a slave seller the admirable hero of a novel. But in 1720, when Defoe   published Robinson Crusoe, no readers said boo about   Crusoe’s occupation, because slavery was the norm from one end of the world   to another. Rules and names differed from place to place, but coerced labor   was everywhere, building roads, serving aristocrats, and fighting wars.   Slaves teemed in the Ottoman Empire, Mughal India, and Ming China. Unfree   hands were less common in continental Europe, but Portugal, Spain, France,   England, and the Netherlands happily exploited slaves by the million in their   American colonies. Few protests were heard; slavery had been part of the   fabric of life since the code of Hammurabi.

Then, in the   space of a few decades in the nineteenth century, slavery, one of humankind’s   most enduring institutions, almost vanished.

The sheer   implausibility of this change is staggering. In 1860, slaves were,   collectively, the single most valuable economic asset in the United States,   worth an estimated $3 billion, a vast sum in those days (and about $10   trillion in today’s money). Rather than investing in factories like northern   entrepreneurs, southern businessmen had sunk their capital into slaves. And   from their perspective, correctly so—masses of enchained men and women had   made the region politically powerful, and gave social status to an entire   class of poor whites. Slavery was the foundation of the social order. It was,   thundered John C. Calhoun, a former senator, secretary of state, and vice   president, “instead of an evil, a good—a positive good.” Yet just a few years   after Calhoun spoke, part of the United States set out to destroy this   institution, wrecking much of the national economy and killing half a million   citizens along the way.

Incredibly,   the turn against slavery was as universal as slavery itself. Great Britain,   the world’s biggest human trafficker, closed down its slave operations in   1808, though they were among the nation’s most profitable industries. The   Netherlands, France, Spain, and Portugal soon followed. Like stars winking   out at the approach of dawn, cultures across the globe removed themselves   from the previously universal exchange of human cargo. Slavery still exists   here and there, but in no society anywhere is it formally accepted as part of   the social fabric.

Historians   have provided many reasons for this extraordinary transition. But one of the   most important is that abolitionists had convinced huge numbers of ordinary   people around the world that slavery was a moral disaster. An institution   fundamental to human society for millennia was swiftly dismantled by ideas   and a call to action, loudly repeated.

In the last   few centuries, such profound changes have occurred repeatedly. Since the   beginning of our species, for instance, every known society has been based on   the domination of women by men. (Rumors of past matriarchal societies abound,   but few archaeologists believe them.) In the long view, women’s lack of   liberty has been as central to the human enterprise as gravitation is to the   celestial order. The degree of suppression varied from time to time and place   to place, but women never had an equal voice; indeed, some evidence exists   that the penalty for possession of two X chromosomes increased with   technological progress. Even as the industrial North and agricultural South   warred over the treatment of Africans, they regarded women identically: in   neither half of the nation could they attend college, have a bank account, or   own property. Equally confining were women’s lives in Europe, Asia, and   Africa. Nowadays women are the majority of U.S. college students, the   majority of the workforce, and the majority of voters. Again, historians   assign multiple causes to this shift in the human condition, rapid in time,   staggering in scope. But one of the most important was the power of ideas—the   voices, actions, and examples of suffragists, who through decades of ridicule   and harassment pressed their case. In recent years something similar seems to   have occurred with gay rights: first a few lonely advocates, censured and   mocked; then victories in the social and legal sphere; finally, perhaps, a   slow movement to equality.

Less well   known, but equally profound: the decline in violence. Foraging societies   waged war less brutally than industrial societies, but more frequently.   Typically, archaeologists believe, about a quarter of all hunters and   gatherers were killed by their fellows. Violence declined somewhat as humans   gathered themselves into states and empires, but was still a constant presence.   When Athens was at its height in the fourth and fifth centuries BC, it was   ever at war: against Sparta (First and Second Peloponnesian Wars, Corinthian   War); against Persia (Greco-Persian Wars, Wars of the Delian League); against   Aegina (Aeginetan War); against Macedon (Olynthian War); against Samos   (Samian War); against Chios, Rhodes, and Cos (Social War).

In this   respect, classical Greece was nothing special—look at the ghastly histories   of China, sub-Saharan Africa, or Mesoamerica. Similarly, early modern   Europe’s wars were so fast and furious that historians simply gather them   into catchall titles like the Hundred Years’ War, followed by the shorter but   even more destructive Thirty Years’ War. And even as Europeans and their   descendants paved the way toward today’s concept of universal human rights by   creating documents like the Bill of Rights and the Declaration of the Rights   of Man and of the Citizen, Europe remained so mired in combat that it fought   two conflicts of such massive scale and reach they became known as “world”   wars.

Since the   Second World War, however, rates of violent death have fallen to the lowest   levels in known history. Today, the average person is far less likely to be   slain by another member of the species than ever before—an extraordinary   transformation that has occurred, almost unheralded, in the lifetime of many   of the people reading this article. As the political scientist Joshua   Goldstein has written, “we are winning the war on war.” Again, there are   multiple causes. But Goldstein, probably the leading scholar in this field,   argues that the most important is the emergence of the United Nations and   other transnational bodies, an expression of the ideas of peace activists   earlier in the last century.

As a   relatively young species, we have an adolescent propensity to make a mess: we   pollute the air we breathe and the water we drink, and appear stalled in an   age of carbon dumping and nuclear experimentation that is putting countless   species at risk including our own. But we are making undeniable progress   nonetheless. No European in 1800 could have imagined that in 2000 Europe   would have no legal slavery, women would be able to vote, and gay people   would be able to marry. No one could have guessed a continent that had been   tearing itself apart for centuries would be free of armed conflict, even amid   terrible economic times. Given this record, even Lynn Margulis might pause   (maybe).

Preventing Homo   sapiens from destroying itself à la Gause would require a still   greater transformation—behavioral plasticity of the highest order—because we   would be pushing against biological nature itself. The Japanese have an   expression, hara hachi bu,which means, roughly speaking, “belly   80 percent full.” Hara hachi buis shorthand for an ancient   injunction to stop eating before feeling full. Nutritionally, the command   makes a great deal of sense. When people eat, their stomachs produce peptides   that signal fullness to the nervous system. Unfortunately, the mechanism is   so slow that eaters frequently perceive satiety only after they have consumed   too much—hence the all-too-common condition of feeling bloated or sick from   overeating. Japan—actually, the Japanese island of Okinawa—is the only place   on earth where large numbers of people are known to restrict their own   calorie intake systematically and routinely. Some researchers claim   that hara hachi bu is responsible for Okinawans’ notoriously   long life spans. But I think of it as a metaphor for stopping before the   second inflection point, voluntarily forswearing short-term consumption to   obtain a long-term benefit.

Evolutionarily   speaking, a species-wide adoption of hara hachi buwould be   unprecedented. Thinking about it, I can picture Lynn Margulis rolling her   eyes. But is it so unlikely that our species, Canbys one and all, would be   able to do exactly that before we round that fateful curve of the second   inflection point and nature does it for us?

I can imagine   Margulis’s response: You’re imagining our species as some sort of   big-brained, hyperrational, benefit-cost-calculating computer! A better   analogy is the bacteria at our feet! Still, Margulis would be the first to   agree that removing the shackles from women and slaves has begun to unleash   the suppressed talents of two-thirds of the human race. Drastically reducing   violence has prevented the waste of countless lives and staggering amounts of   resources. Is it really impossible to believe that we wouldn’t use those   talents and those resources to draw back before the abyss?

Our record of   success is not that long. In any case, past successes are no guarantee of the   future. But it is terrible to suppose that we could get so many other things   right and get this one wrong. To have the imagination to see our potential   end, but not have the imagination to avoid it. To send humankind to the moon   but fail to pay attention to the earth. To have the potential but to be   unable to use it—to be, in the end, no different from the protozoa in the   petri dish. It would be evidence that Lynn Margulis’s most dismissive beliefs   had been right after all. For all our speed and voraciousness, our changeable   sparkle and flash, we would be, at last count, not an especially interesting   species.


About aschvetahata

Interests: Sanskrit, Hindi, Classical Greek, Latin, French, German Philosophy: especially Friedrich Nietzsche and South Asian Indian thought Computers
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