to what certainty does descartes’ methodical doubt lead? is he right about that?

(This essay was a finalist for a 2013 National Magazine Laurels in the Essay category.)

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 about important biologists in the concluding half century—she literally helped to reorder the tree of life, convincing her colleagues that it did non consist of 2 kingdoms (plants and animals), merely five or even six (plants, animals, fungi, protists, and two types of leaner).

Until Margulis'southward death concluding twelvemonth, she lived in my town, and I would bump into her on the street from time to time. She knew I was interested in environmental, and she liked to needle me. Hey, Charles, she would phone call out, are you lot still all worked up about protecting endangered species?

Margulis was no apologist for unthinking destruction. Still, she couldn't assistance regarding conservationists' preoccupation with the fate of birds, mammals, and plants as bear witness of their ignorance about the greatest source of evolutionary creativity: the microworld of leaner, fungi, and protists. More than ninety pct 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 tin exercise things undreamed of past clumsy mammals like us: form behemothic supercolonies, reproduce either asexually or past swapping genes with others, routinely incorporate Dna from entirely unrelated species, merge into symbiotic beings—the list is every bit endless equally it is astonishing. Microorganisms have changed the face of the world, crumbling stone and even giving rise to the oxygen we exhale. Compared to this power and variety, Margulis liked to tell me, pandas and polar bears were biological epiphenomena—interesting and fun, perhaps, simply non actually significant.

Does that use to human beings, too? I once asked her, feeling like someone whining to Copernicus about why he couldn't motion the earth a little closer to the center of the universe. Aren't we special at all?

This was just chitchat on the street, then I didn't write anything down. But every bit 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.

OF LICE AND MEN

Why and how did humankind become "unusually successful"? And what, to an evolutionary biologist, does "success" mean, if self-devastation is function of the definition? Does that cocky-destruction include the remainder of the biosphere? What are human beings in the grand scheme of things anyhow, and where are nosotros headed? What is human nature, if in that location is such a affair, and how did we acquire it? What does that nature portend for our interactions with the surround? With 7 billion of us crowding the planet, it's difficult to imagine more vital questions.

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

Information technology occurred to him that the 2 louse subspecies could be used equally an evolutionary probe. P. humanus capitis, the head louse, could be an aboriginal annoyance, because human beings have always had hair for it to infest. But P. humanus corporis, the body louse, must non be particularly old, considering its need for article of clothing meant that it could not have existed while humans went naked. Humankind'south dandy coverup had created a new ecological niche, and some head lice had rushed to fill up 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 information technology seemed probable. Merely if his thought were right, discovering when the trunk louse diverged from the head louse would provide a rough appointment for when people first invented and wore clothing.

The subject was anything just 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 advent of the wearer, something that has proven to be of inescapable involvement to Human being sapiens. Clothing is ornament and emblem; it separates human beings from their earlier, un-self-conscious state. (Animals run, swim, and fly without clothing, merely only people can be naked.) The invention of clothing was a sign that a mental shift had occurred. The human earth had become a realm of circuitous, symbolic artifacts.

With two colleagues, Stoneking measured the difference between snippets of DNA in the two louse subspecies. Because DNA is idea to pick upwards modest, random mutations at a roughly abiding rate, scientists utilise the number of differences between two populations to tell how long ago they diverged from a common antecedent—the greater the number of differences, the longer the separation. In this case, the torso louse had separated from the head louse virtually 70,000 years ago. Which meant, Stoneking hypothesized, that clothing likewise dated from about seventy,000 years ago.

And not just vesture. As scientists accept established, a host of remarkable things occurred to our species at about that time. It marked a dividing line in our history, 1 that made us who we are, and pointed us, for better and worse, toward the world nosotros now accept created for ourselves.

Man sapiens emerged on the planet nearly 200,000 years agone, researchers believe. From the starting time, our species looked much as it does today. If some of those long-ago people walked by us on the street at present, we would think they looked and acted somewhat oddly, but not that they weren't people. Just those anatomically modern humans were non, every bit anthropologists say, behaviorally modern. Those start people had no language, no clothing, no fine art, no religion, nada but the simplest, unspecialized tools. They were little more advanced, technologically speaking, than their predecessors—or, for that matter, mod chimpanzees. (The big exception was fire, but that was first controlled by Human being erectus, i of our ancestors, a million years ago or more.) Our species had and then little capacity for innovation that archaeologists have found almost no show of cultural or social modify during our start 100,000 years of existence. Equally of import, for almost all that fourth dimension these early humans were bars to a single, small surface area in the hot, dry out savanna of East Africa (and perchance a 2d, still smaller area in southern Africa).

Merely now jump forwards l,000 years. East Africa looks much the same. So practice the humans in it—merely suddenly they are drawing and carving images, weaving ropes and baskets, shaping and wielding specialized tools, burying the expressionless in formal ceremonies, and perhaps worshipping supernatural beings. They are wearing apparel—lice-filled wearing apparel, to be sure, but apparel 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, fifty,000 years is an instant, a finger snap, a rounding error. Nonetheless, virtually researchers believe that in that flicker of time, favorable mutations swept through our species, transforming anatomically modernistic humans into behaviorally modern humans. The idea is not cool: in the last 400 years, domestic dog breeders converted village dogs into creatures that act as differently as foxhounds, edge 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 amending of the wet grey thing within our skulls. One candidate explanation is that in this menstruum people adult hybrid mental abilities by interbreeding with Neanderthals. (Some Neanderthal genes indeed appear to be in our genome, though nobody is however sure of their function.) Another putative cause is symbolic language—an invention that may have tapped latent creativity and aggressiveness in our species. A tertiary 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 concrete world around us. The quondam, in this view, allows us to come up with creative new strategies to attain a goal, whereas the latter enables u.s.a. to execute the physical tactics required by those strategies.

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

CHILDREN OF 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'south biggest crater lake, and ejected the equivalent of as much as 3,000 cubic kilometers of rock, plenty to comprehend the District of Columbia in a layer of magma and ash that would reach to the stratosphere. A gigantic plume spread due west, enveloping south asia in tephra (rock, ash, and dust). Drifts in Pakistan and India reached every bit high equally 6 meters. Smaller tephra beds blanketed the Middle Eastward and E Africa. Keen rafts of pumice filled the ocean and drifted near to Antarctica.

In the long run, the eruption raised Asian soil fertility. In the brusque term, it was catastrophic. Dust hid the sunday for as much as a decade, plunging the earth into a years-long wintertime accompanied past widespread drought. A vegetation collapse was followed past a plummet in the species that depended on vegetation, followed past a plummet 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, Human being sapiens' numbers shrank dramatically, perhaps to a few yard people—the size of a big urban high school. The clearest bear witness of this bottleneck is also its main legacy: humankind'south remarkable genetic uniformity. Countless people take viewed the differences between races as worth killing for, simply compared to other primates—fifty-fifty compared to most other mammals—human beings are almost indistinguishable, genetically speaking. DNA is fabricated from exceedingly long bondage of "bases." Typically, almost one out of every two,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 clogging. 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 meliorate planning skills, for example—can of a sudden become more than common, finer reshaping the species within a few generations equally one time-unusual traits become widespread.

Did Toba, as theorists like Richard Dawkins take argued, cause an evolutionary bottleneck that set off the cosmos of behaviorally modern people, perhaps by helping previously rare genes—Neanderthal Deoxyribonucleic acid 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 modify?

For now, the answers are the subject area 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 and then fast into the tephra that homo footprints appeared in Australia within as few every bit 10,000 years, perhaps within four,000 or five,000. Stay-at-abode Homo sapiens ane.0, a wallflower that would never take 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 similar is to consider Solenopsis invicta, the red imported fire ant. Geneticists believe that S. invicta originated in northern Argentina, an surface area with many rivers and frequent floods. The floods wipe out ant nests. Over the millennia, these pocket-sized, furiously agile creatures have acquired the ability to reply to rising h2o by coalescing into huge, floating, pullulating balls—workers on the outside, queen in the heart—that migrate to the edge of the overflowing. Once the waters recede, colonies swarm back into previously flooded country so rapidly that Due south. invicta actually can use the devastation to increase its range.

In the 1930s, Solenopsis invicta was transported to the United States, probably in ship anchor, 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 burn down ants. From the ant's indicate of view, it had been dumped into an empty, recently flooded expanse. South. invicta took off, never looking dorsum.

The initial incursion watched by Wilson was likely just a few thousand individuals—a number small enough to suggest that random, bottleneck-fashion genetic modify played a role in the species' subsequent history in this state. In their Argentine birthplace, burn-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 pismire species forth the manner—models of zeal and rapacity. Transformed past chance and opportunity, new-model Southward. invictus needed only a few decades to conquer nigh of the southern United States.

Homo sapiens did something like in the wake of Toba. For hundreds of thousands of years, our species had been restricted to East Africa (and, peradventure, a similar area in the s). At present, abruptly, new-model Homo sapiens were racing beyond the continents like so many imported burn ants. The divergence between humans and fire ants is that burn ants specialize in disturbed habitats. Humans, too, specialize in disturbed habitats—but nosotros practice the disturbing.

THE WORLD IS A PETRI DISH

As a student at the Academy 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 draw the results in his grant awarding.

By today's standards, his methodology was simplicity itself. Gause placed one-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 past adding h2o, 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 exam tubes was a pocket ecosystem, a food web with a unmarried 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. Simply the book was not plenty to become Gause a fellowship; the Rockefeller Foundation turned down the twenty-four-year-former Soviet educatee as comparatively eminent. Gause could not visit the The states for another twenty years, by which time he had indeed get eminent, but as an antibiotics researcher.

What Gause saw in his examination 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 Southward. At first the number of protozoans grows slowly, and the graph line slowly ascends to the right. Just then the line hits an inflection betoken, and of a sudden rockets upwardly—a frenzy of exponential growth. The mad rise continues until the organism begins to run out of food, at which point there is a 2nd inflection signal, and the growth bend levels off once more equally leaner 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 course at the University of Massachusetts with a fourth dimension-lapse video of Proteus vulgaris, a bacterium that lives in the gastrointestinal tract. To humans, she said, P. vulgaris is mainly notable equally a crusade of urinary-tract infections. Left solitary, information technology divides nigh every xv 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 embrace 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. vulgaris from reproducing. This, Margulis said, is natural selection, Darwin's nifty insight. All living creatures have the same purpose: to make more of themselves, ensuring their biological future past the simply means available. Natural selection stands in the mode of this goal. It prunes back almost all species, restricting their numbers and confining their range. In the human being 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, contest 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 so its colonies slam into the second inflection bespeak: the border of the dish. When the dish's food supply is exhausted, P. vulgaris experiences a miniapocalypse.

By luck or superior accommodation, a few species manage to escape their limits, at least for a while. Nature's success stories, they are like Gause's protozoans; the earth is their petri dish. Their populations grow exponentially; they have over large areas, overwhelming their environs as if no forcefulness opposed them. Then they annihilate themselves, drowning in their ain wastes or starving from lack of nutrient.

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

THE WHIP HAND

No more than than a few hundred people initially migrated from Africa, if geneticists are correct. Simply they emerged into landscapes that by today's standards were every bit rich as Eden. Absurd 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 yet merely in the initial stages of Gause's oddly shaped curve. Ten k years agone, near demographers believe, we numbered barely 5 one thousand thousand, about one human being for every hundred square kilometers of the globe's land surface. Homo sapiens was a scarcely noticeable dusting on the surface of a planet dominated past microbes. Nevertheless, at about this time—x,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 accept been part of the man diet for nigh as long as in that location accept been humans to eat them. (The earliest testify comes from Mozambique, where researchers constitute tiny $.25 of 105,000-year-quondam sorghum on ancient scrapers and grinders.) In some cases people may have watched over patches of wild grain, returning to them twelvemonth later on year. Yet despite the effort and intendance the plants were not domesticated. As botanists say, wild cereals "shatter"—individual grain kernels fall off as they ripen, scattering grain haphazardly, making it incommunicable to harvest the plants systematically. Merely 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, outset in southern Turkey, later in half a dozen other places, early farmers created landscapes that, then to speak, waited for hands to harvest them.

Farming converted most of the habitable earth into a petri dish. Foragers manipulated their environs 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 consume. Nonetheless, their diets were largely restricted to what nature happened to provide in any given fourth dimension and flavor. Agronomics gave humanity the whip hand. Instead of natural ecosystems with their haphazard mix of species (then many useless organisms guzzling upward resources!), farms are taut, disciplined communities conceived and dedicated to the maintenance of a unmarried species: us.

Before agriculture, the Ukraine, American Midwest, and lower Yangzi were barely hospitable nutrient deserts, sparsely inhabited landscapes of insects and grass; they became breadbaskets equally people scythed away suites of species that used soil and water we wanted to boss and replaced them with wheat, rice, and maize (corn). To i of Margulis'southward beloved bacteria, a petri dish is a compatible 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, nosotros divided and multiplied across the newly opened land. It had taken Homo sapiens 2.0, behaviorally modern humans, not even 50,000 years to attain the uttermost corners of the world. Human being 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 effectually the elbow of the first inflection betoken in the seventeenth and eighteenth centuries, when American crops like potatoes, sweetness potatoes, and maize were introduced to the rest of the globe. 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 tin can really exist punished if they have an extra-bounteous harvest. Past contrast, potatoes and sugariness potatoes grow underground, which means that yields are not express by the plant's architecture. Wheat farmers in Edinburgh and rice farmers in Edo akin discovered they could harvest four times as much dry nutrient 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 actress-thick stem 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 plough 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 pharmacist, Justus von Liebig, discovered that plant growth was limited past the supply of nitrogen. Without nitrogen, neither plants nor the mammals that eat plants tin create proteins, or for that matter the Dna and RNA that direct their production. Pure nitrogen gas (N2) is plentiful in the air merely plants are unable to absorb it, considering the ii nitrogen atoms in N2 are welded then tightly together that plants cannot divide them apart for employ. 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 "greenish manures" replenished the land. Today nosotros 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 loftier-intensity fertilizer—nitrogen-rich guano from Peru at first, then nitrates from mines in Republic of 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. Near 3,000 people died.

2 more German chemists, Fritz Haber and Carl Bosch, came to the rescue, discovering the primal steps to making synthetic fertilizer from fossil fuels. (The procedure 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 also known every bit they should be; their discovery, the Haber-Bosch procedure, has literally inverse the chemic composition of the earth, a feat previously reserved for microorganisms. Farmers accept injected then much synthetic fertilizer into the soil that soil and groundwater nitrogen levels accept risen worldwide. Today, roughly a third of all the protein (creature and vegetable) consumed by humankind is derived from synthetic nitrogen fertilizer. Some other way of putting this is to say that Haber and Bosch enabled Homo sapiens to 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 establish breeders in the 1950s and 1960s are often said to have prevented another billion deaths. Antibiotics, vaccines, and h2o-handling plants as well saved lives past pushing back humankind'southward bacterial, viral, and fungal enemies. With almost no surviving biological competition, humankind had ever more unhindered admission to the planetary petri dish: in the by 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 bend, human beings "now advisable most twoscore% . . . of potential terrestrial productivity." This figure dates from 1986—a famous estimate by a squad of Stanford biologists. X years afterward, a 2nd Stanford team calculated that the "fraction of the land'south biological production that is used or dominated" by our species had risen to every bit much as 50 percent. In 2000, the chemist Paul Crutzen gave a name to our fourth dimension: the "Anthropocene," the era in which Homo sapiens became a force operating on a planetary scale. That yr, half of the earth's accessible fresh water was consumed past human beings.

Lynn Margulis, it seems safe to say, would have scoffed at these assessments of human being domination over the natural earth, which, in every case I know of, do non take into account the enormous impact of the microworld. But she would non accept disputed the central idea: Human sapiens has become a successful species, and is growing appropriately.

If we follow Gause's blueprint, growth volition continue at a febrile speed until we hitting the second inflection signal. At that fourth dimension we will have wearied the resources of the global petri dish, or effectively fabricated the atmosphere toxic with our carbon-dioxide waste material, or both. Subsequently that, human being life volition be, briefly, a Hobbesian nightmare, the living overwhelmed by the dead. When the rex falls, so practise his minions; information technology is possible that our autumn might also take downwards nearly mammals and many plants. Peradventure sooner, quite likely afterwards, in this scenario, the earth will again exist a choir of leaner, fungi, and insects, as it has been through most of its history.

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

Every bit PLASTIC As CANBY

In The Phantom Tollbooth, Norton Juster's archetype, pun-filled run a risk tale, the young Milo and his faithful companions unexpectedly detect themselves transported to a bleak, mysterious island. Encountering a man in a tweed jacket and beanie, Milo asks him where they are. The human replies by asking if they know who he is—the human being is, plainly, dislocated on the subject. Milo and his friends confer, then ask if he can describe himself.

"Yes, indeed," the man replied happily. "I'thousand as alpine as can be"—and he grew directly up until all that could be seen of him were his shoes and stockings—"and I'chiliad as short as tin be"—and he shrank downwardly to the size of a pebble. "I'm as generous as can be," he said, handing each of them a big red apple, "and I'm as selfish as can be," he snarled, grabbing them back again.

In brusk society, the companions learn that the man is as strong as can exist, weak equally tin be, smart equally tin be, stupid equally tin exist, graceful as tin can exist, impuissant as—you get the picture. "Is that any aid to yous?" he asks. Over again, Milo and his friends confer, and realize that the respond is actually quite simple:

"Without a dubiety," Milo concluded brightly, "you must be Canby."

"Of form, yes, of course," the man shouted. "Why didn't I think of that? I'thou as happy as tin exist."

With Canby, Juster presumably meant to mock a certain kind of babyish, uncommitted man-child. But I tin can't aid thinking of poor old Canby as exemplifying ane of humankind's greatest attributes: behavioral plasticity. The term was coined in 1890 past the pioneering psychologist William James, who defined it every bit "the possession of a construction weak plenty to yield to an influence, but strong enough not to yield all at one time." Behavioral plasticity, a defining feature of Human sapiens' big brain, means that humans tin can change their habits; almost equally a matter of form, people alter careers, quit smoking or take upwardly vegetarianism, catechumen to new religions, and migrate to afar lands where they must larn strange languages. This plasticity, this Canby-hood, is the hallmark of our transformation from anatomically modern Homo sapiens to behaviorally modern Human sapiens—and the reason, perhaps, we were able to survive when Toba reconfigured the landscape.

Other creatures are much less flexible. Like apartment-habitation cats that compulsively hibernate in the closet when visitors make it, they accept 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 explicate how this could come well-nigh. (Nobody knows for certain, but some researchers at present think that particular genes give their possessors a heightened, inborn sensation of their environment, which can pb both to useless, neurotic sensitivity and greater power to discover and adapt to new situations.)

Plasticity in individuals is mirrored by plasticity on a societal level. The caste organization in social species similar honeybees is elaborate and finely tuned but fixed, as if in amber, in the loops of their DNA. Some leafcutter ants are said to accept, next to human beings, the biggest and most circuitous societies on earth, with elaborately coded behavior that reaches from disposal of the dead to complex agronomical systems. Housing millions of individuals in inconceivably ramose subterranean networks, leafcutter colonies are "World's ultimate superorganisms," Edward O. Wilson has written. But they are incapable of central modify. The centrality and authority of the queen cannot exist challenged; the tiny minority of males, used only to inseminate queens, will never larn new responsibilities.

Human societies are far more varied than their insect cousins, of grade. Merely the true difference is their plasticity. It is why humankind, a species of Canbys, has been able to motility into every corner of the globe, and to control what we notice there. Our power to alter ourselves to extract resources from our surround with always-increasing efficiency is what has made Homo sapiens a successful species. It is our greatest blessing.

Or was our greatest blessing, anyway.

DISCOUNT RATES

By 2050, demographers predict, as many every bit ten billion human beings volition walk the earth, iii billion more than today. Non only will more people be than ever before, they will be richer than e'er before. In the terminal three decades hundreds of millions in Cathay, India, and other formerly poor places take lifted themselves from destitution—arguably the nearly important, and certainly the most heartening, accomplishment of our time. Still, similar all human being enterprises, this bang-up success will pose slap-up difficulties.

In the past, rise 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 near basic of all: feeding these extra mouths. To agronomists, the prospect is sobering. The newly flush will not want their ancestors' gruel. Instead they will inquire for pork and beefiness and lamb. Salmon will sizzle on their outdoor grills. In wintertime, 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 resource to produce than simple peasant agriculture. Already 35 percent of the world'south grain harvest is used to feed livestock. The process is terribly inefficient: betwixt seven and ten kilograms of grain are required to produce one kilogram of beef. Not only volition the world's farmers have to produce enough wheat and maize to feed 3 billion more people, they will take to produce enough to give them all hamburgers and steaks. Given present patterns of food consumption, economists believe, we will demand 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 function 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 modify!) Others claim that only intense exploitation of scientific knowledge can save us. (Institute super-productive, genetically modified crops at present! Switch to nuclear power to halt climate change!) No thing which course is chosen, though, it will require radical, large-calibration transformations in the human being enterprise—a daunting, hideously expensive task.

Worse, the ship is as well large to turn apace. The globe'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 loftier-tech route is chosen, genetically modified crops cannot exist bred and tested overnight. Similarly, carbon-sequestration techniques and nuclear power plants cannot exist deployed instantly. Changes must be planned and executed decades in accelerate of the usual signals of crunch, but that's like asking good for you, happy sixteen-year-olds to write living wills.

Not merely is the task daunting, it'southward strange. In the proper name of nature, we are asking human being beings to exercise something deeply unnatural, something no other species has ever done or could e'er exercise: constrain its ain growth (at to the lowest degree 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 Commonwealth of australia, Burmese pythons in Florida—all these successful species take 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 dorsum. At present we are request Homo sapiens to fence itself in.

What a peculiar thing to ask! Economists like to talk well-nigh the "discount rate," which is their term for preferring a bird in hand today over ii in the bush tomorrow. The term sums up part of our man nature equally well. Evolving in modest, constantly moving bands, we are as hard-wired to focus on the firsthand 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 side by side year in Republic of croatia, Cambodia, or the Congo. Rightly and then, evolutionists point out: Americans are far more likely to be killed at that stoplight today than in the Congo next yr. Yet here we are request governments to focus on potential planetary boundaries that may not exist reached for decades. Given the discount rate, zero could exist more understandable than the U.South. Congress'southward failure to grapple with, say, climatic change. From this perspective, is there whatever reason to imagine that Homo sapiens, different 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 but office of the natural lodge, the reply should exist clear. All life is similar at base of operations. All species seek without pause to make more than of themselves—that is their goal. By multiplying till we reach our maximum possible numbers, even as we have out much of the planet, we are fulfilling our destiny.

From this vantage, the reply to the question whether nosotros are doomed to destroy ourselves is yep. Information technology should be obvious.

Should exist—simply peradventure is not.

HARA HACHI BU

When I imagine the profound social transformation necessary to avoid cataclysm, I think about Robinson Crusoe, hero of Daniel Defoe's famous novel. Defoe clearly intended his hero to be an exemplary human. 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 plain didn't know that citrus and goats were non 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 helm recapture his ship and offers the defeated mutineers a choice: trial in England or permanent adjournment to the island. All choose the latter. Crusoe has harnessed so much of the island's productive power to human utilize that fifty-fifty a gaggle of inept seamen tin can survive in that location in comfort.

To go Crusoe on his unlucky voyage, Defoe made him an officer on a slave send, transporting captured Africans to South America. Today, no writer would make a slave seller the beauteous hero of a novel. Simply in 1720, when Defoe published Robinson Crusoe, no readers said boo virtually Crusoe's occupation, considering slavery was the norm from one finish of the globe to another. Rules and names differed from identify to place, merely coerced labor was everywhere, edifice roads, serving aristocrats, and fighting wars. Slaves teemed in the Ottoman Empire, Mughal India, and Ming Communist china. Unfree hands were less common in continental Europe, just 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 infinite of a few decades in the nineteenth century, slavery, one of humankind's about indelible institutions, nearly vanished.

The sheer implausibility of this change is staggering. In 1860, slaves were, collectively, the single most valuable economic asset in the United states of america, worth an estimated $3 billion, a vast sum in those days (and near $10 trillion in today'due south money). Rather than investing in factories like northern entrepreneurs, southern businessmen had sunk their capital into slaves. And from their perspective, correctly and then—masses of enchained men and women had made the region politically powerful, and gave social condition to an entire form of poor whites. Slavery was the foundation of the social social club. It was, thundered John C. Calhoun, a old senator, secretarial assistant of country, and vice president, "instead of an evil, a practiced—a positive expert." Nonetheless just a few years after Calhoun spoke, function of the United States gear up out to destroy this institution, wrecking much of the national economy and killing half a million citizens forth the way.

Incredibly, the turn confronting 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 amid the nation'due south most profitable industries. The Netherlands, France, Kingdom of spain, and Portugal presently followed. Like stars winking out at the approach of dawn, cultures beyond the earth removed themselves from the previously universal exchange of human cargo. Slavery still exists here and at that place, but in no order anywhere is it formally accepted as part of the social fabric.

Historians have provided many reasons for this boggling transition. But i of the about important is that abolitionists had convinced huge numbers of ordinary people around the world that slavery was a moral disaster. An establishment central to homo lodge for millennia was swiftly dismantled by ideas and a call to activity, loudly repeated.

In the last few centuries, such profound changes take occurred repeatedly. Since the beginning of our species, for instance, every known gild has been based on the domination of women by men. (Rumors of by matriarchal societies grow, but few archaeologists believe them.) In the long view, women's lack of liberty has been every bit primal to the human enterprise every bit gravitation is to the celestial guild. The caste of suppression varied from time to fourth dimension and identify to place, but women never had an equal phonation; indeed, some evidence exists that the penalty for possession of two X chromosomes increased with technological progress. Fifty-fifty 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 higher, have a bank business relationship, or ain property. Every bit confining were women's lives in Europe, Asia, and Africa. Nowadays women are the bulk of U.Southward. 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 telescopic. Simply one of the most important was the ability of ideas—the voices, deportment, and examples of suffragists, who through decades of ridicule and harassment pressed their case. In recent years something similar seems to accept occurred with gay rights: outset a few lonely advocates, censured and mocked; then victories in the social and legal sphere; finally, mayhap, a slow movement to equality.

Less well known, but equally profound: the refuse in violence. Foraging societies waged state of war less brutally than industrial societies, simply more than oft. Typically, archaeologists believe, about a quarter of all hunters and gatherers were killed by their fellows. Violence declined somewhat every bit humans gathered themselves into states and empires, but was still a constant presence. When Athens was at its acme in the 4th and fifth centuries BC, it was always at war: against Sparta (Offset and Second Peloponnesian Wars, Corinthian War); against Persia (Greco-Persian Wars, Wars of the Delian League); confronting 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 Mainland china, sub-Saharan Africa, or Mesoamerica. Similarly, early modern Europe'southward wars were so fast and furious that historians simply get together them into catchall titles similar the Hundred Years' War, followed by the shorter only even more destructive Xxx Years' War. And even every bit Europeans and their descendants paved the way toward today's concept of universal human rights by creating documents like the Neb of Rights and the Proclamation of the Rights of Man and of the Citizen, Europe remained then mired in gainsay that information technology fought 2 conflicts of such massive scale and reach they became known as "globe" wars.

Since the Second World State of war, withal, rates of trigger-happy expiry accept 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 earlier—an extraordinary transformation that has occurred, nearly 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. Merely Goldstein, probably the leading scholar in this field, argues that the most of import is the emergence of the Un and other transnational bodies, an expression of the ideas of peace activists earlier in the concluding century.

As a relatively immature species, nosotros take an adolescent propensity to brand 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 ain. Just 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 exist able to marry. No one could accept guessed a continent that had been violent itself autonomously for centuries would exist free of armed conflict, fifty-fifty 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 nonetheless greater transformation—behavioral plasticity of the highest order—considering we would be pushing against biological nature itself. The Japanese take an expression, hara hachi bu, which means, roughly speaking, "belly fourscore percent total." Hara hachi bu is shorthand for an ancient injunction to finish eating before feeling total. Nutritionally, the command makes a great deal of sense. When people eat, their stomachs produce peptides that indicate fullness to the nervous organisation. Unfortunately, the mechanism is and so slow that eaters frequently perceive satiety but afterward they take consumed too much—hence the all-too-mutual condition of feeling bloated or sick from overeating. Japan—really, the Japanese isle 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. Just I recall of it every bit a metaphor for stopping earlier the second inflection bespeak, voluntarily forswearing brusque-term consumption to obtain a long-term benefit.

Evolutionarily speaking, a species-wide adoption of hara hachi bu would be unprecedented. Thinking nearly information technology, I tin can picture show Lynn Margulis rolling her eyes. But is information technology so unlikely that our species, Canbys one and all, would be able to do exactly that before we round that fateful bend of the second inflection point and nature does information technology for u.s.?

I tin can imagine Margulis's response: You're imagining our species as some sort of large-brained, hyperrational, benefit-cost-computing computer! A better analogy is the bacteria at our anxiety! Still, Margulis would be the start 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 material of countless lives and staggering amounts of resources. Is it actually incommunicable to believe that we wouldn't use those talents and those resource to draw back earlier 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 incorrect. To have the imagination to see our potential end, merely not have the imagination to avert it. To send humankind to the moon but fail to pay attention to the world. To have the potential but to exist unable to utilise it—to exist, in the end, no different from the protozoa in the petri dish. Information technology 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 specially interesting species. O

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Source: https://orionmagazine.org/article/state-of-the-species/

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