In the time frame of evolution, the ultimate fate of all populations is extinction. Extinction is the moment when the last surviving individual of a population bites the dust. Some populations have gone extinct in little more than a single human lifetime. The dodo of Mauritius was so unwary that early visitors to the island, in the 1600s, found the flightless bird to be easy prey for food. However, it is likely that hunting was not the sole cause of the dodo’s extinction. Remote island populations (such as those on Mauritius) are often much more vulnerable to population fluctuations, particularly in the face of habitat destruction due to human activities and colonization. Mauritius’s forests (the dodo’s preferred habitat) were being cleared for timber precisely at the time the dodo population was declining. By 1700, a hundred years after it was discovered, the dodo was extinct, along with several other large vertebrate populations on Mauritius.
Populations are interconnected in complex ways that are often hard to unravel. The dodo’s extinction coincided with the near extinction of a tree, Sideroxylon grandiflorum, known as the tambalacoque, or dodo tree. Some biologists have speculated that the trees’ seeds needed to be processed by the dodos’ gravel-filled gizzards before they could germinate. Others have suggested that the real culprits were the domesticated pigs and goats who trampled the soil and grazed it bare, making germination of the tambalacoque impossible. These animals invaded Mauritius in swarms along with the first Westerners, and widespread deforestation followed in their wake. Whatever the case, the fate of the dodos, trees, and the invasive species were linked; the original species, vulnerable from the start, declined as the newcomers thrived.
Extinction is caused by unobvious, often multifarious factors. It’s not always clear when a species has gone extinct. Other species are artificially sustained by human intervention. The tambalacoque is prized for its hardwood; modern Mauritian farmers now help the seeds germinate by abrading them, or running them through gem polishers. It is still unclear if this action is crucial to the species’ survival, but either way we can be certain that the tambalacoque lives on at least partly because human beings find it too valuable to be allowed to die out.184
Many American families have witnessed a real-time population crisis in a native tree species. If you live east of the Mississippi you’ve probably heard about the demise of elm and chestnut trees. Most small towns in the eastern United States lined their main streets with elms. The street signs still stand (how many of you readers live on an Elm Street?), but the trees are long since dead. Our grandparents may remember these enormous elms shading their streets in summertime. But by 1960 tens of millions of mature trees had died and were cut down. Their death was due to a beetle infestation from Europe. Logs from Holland, destined for furniture makers in Ohio, brought the beetles to our shores. And the beetles carried a fungus of the genus Ophiostoma, which infests and kills mature elms.
Another arboreal treasure, the American chestnut, met a similar fate. These graceful giants were loved as shade trees, nut producers, and beautifully ornamental and fragrant springtime bloomers. Their tall trunks made lumber that was long, straight, workable, and strong. Many of the old barns that still stand throughout the United States are held up by chestnut beams fourteen inches or more in width. In fact, the old barns that dot the countryside of upstate New York couldn’t have been built without the support of these beams. The size of these barns was limited only by the length of the single beam that supports the roof, and their huge size is a living testimony to the majesty of those old timber stands. Despite its usefulness and healthy population size, the chestnut declined in the twentieth century due to a blight (fungal infection) from Asia. Imported trees carried a fungus from China to America in the first decade of the twentieth century, and it quickly spread to nearly all the chestnuts on this continent. Aggressive logging in the 1920s (to prevent the spread of the blight), along with the disease itself, led to the destruction of most of the timber. The population was nearly decimated; it went from an estimated 3 billion trees at the start of the century to fewer than one thousand mature trees today.
Remarkably, however, the chestnut persists against the odds; some small stands still exist, one of which was planted by an early settler in Wisconsin in the 1800s. These trees are the lucky remnants of a once larger, healthy population. Somehow the remaining stands had a fortunate combination of genes and habitat selection that led to lower susceptibility to fungal infection. One wonders how much of this potentially resistant variation was eliminated by overzealous logging of chestnuts to quell the spread of infection in the last century.
If you look carefully, you may yet find elm trees in the forests of the eastern United States. They aren’t large, they aren’t dominant in number, and they aren’t creating shade the way their ancestors did, but they are in fact growing and reproducing. As with the chestnut trees that you also may find growing in out-of-the-way groves at much-reduced number, these individuals show some degree of resistance to the infestation early in their growth. The problem is, when the elms reach a certain age, usually much younger than their ancestors’ age at maturity, they succumb to the elm beetle and the fungus it brings.
The key to this lesson on trees is that the populations were not vanquished even though all indicators suggested that they should have been. Unlike the dodo, a population in crisis from the get-go (island populations are always fragile), the mature elm and chestnut trees succumbed to disease at the peak of their health and prosperity. Widespread large populations such as these are hard to kill. In fact the species in question have individuals who are still reproducing despite their brief lives. This leads to an interesting generalization about populations and infections: Infections (or infestations, or blights) rarely cause extinction. Large portions of populations may succumb to outbreaks, but there always seems to be some degree of resistance in every population, and some portion will survive.
There are American beech on our property in upstate New York. The beech, like the elm and chestnut, is threatened by a beetle that introduces a fungus into the tree. Beech trees were once abundant and huge, but by the middle of the twentieth century most adults in the populations of New York and New England were dead from disease. Medium-size trees survive, but usually in very remote settings, far from roads and surrounded by evergreens such as hemlock, which seem to insulate the beech from infestation. Again the population is not extinct—it has trees that reach reproductive maturity and produce offspring—but it is devoid of really large, timber-grade individuals. By the age of thirty years or so, beech trees succumb to the disease, whereas their ancestors lived to be more than two hundred years old. The last selective harvesting of timber on my property was around forty years ago, so these trees—obviously avoided by the loggers due to their youthful size—must be at least that old, but not much more. They are likely due to succumb within the next few years. I keep watch, but there’s not much I will be able to do when the disease begins to show. I’ve seen slightly larger trees than those on our property, in forests nearby, that are in various stages of the disease. They tend to be broken, cracking, or bending to one side, with huge gashes in the bark, and showing few to no leaves in the canopy.
These species still exist, but not in a way that would be recognizable to eighteenth-century Indians or settlers. The small stands of trees that have some resistance cling on, though their life cycle has been cut short. It’s important to reflect on resistance and infection in relation to our own population.
Our ancestors would be astonished to know that we no longer worry too much about infections or small cuts or abrasions. There was no such thing as a “minor” injury in the colonial era. Even if you had a doctor on hand to treat a wound, there was no effective treatment to stop any resulting infection. But our antibiotics cannot permanently protect us. Canadian researchers recently discovered a bacterium on raw squid, which was being imported into their country from Korea, that was resistant to carbapenems—the antibiotics of “last resort.” The bacterium itself not particularly dangerous—the bigger threat was the possibility of it being ingested by a human and then passing on its DNA to that individual’s gut bacteria.185 With the increasing prevalence of infections that are untreatable with conventional antibiotics, this hypothetical human, no longer treatable with carbapenems, would die. It astonishes me that stories like this one, of populations and evolution, aren’t leading the news every night. But instead news tends to focus on heroism and sensationalism.
As I write this, the Ebola epidemic in Liberia and Sierra Leone is in fact a top news story. The coverage, however, is skewed toward human-interest aspects—suffering of families, fears of spread in the United States, or most commonly, the bravery of the doctors. As soon as the human interest stories fade, I fear the news coverage will wane. The real story should be the expanding population of the virus (called by its generic name, Ebolavirus) and its doubling rate as seen in the infected people. The doubling rate is a rough measure of how fast a population is growing. It simply reveals the time it takes for a population to double its number of individuals. Since all populations grow exponentially at first (before their growth is slowed down by limiting factors), they follow a predictable pattern that can be depicted by a curve on a two-dimensional graph. One axis of this graph is a measure of elapsed time—years or generations—since the population began. The other axis measures number of individuals. All unchecked populations—those that are free to reproduce without limits, such as pathogens during an outbreak—show an initial, relatively flat trajectory for a period of time. But at some point the curve steepens suddenly, indicating very rapid population growth over little elapsed time. At this point populations are in the steep phase of their growth and are doubling ever faster. For diseases this often means that the pathogen population is out of control.
Ebola is being controlled by health-care workers, so the virus is not exactly free to expand. But the viral population experienced a nearly unchecked exponential growth for the first months of its outbreak. After being contained for nearly thirty-five years in Central Africa, the latest epidemic was first reported in December 2013, in countries with poor health systems, Guinea, Sierra Leone, and Liberia. In July 2014, as indicated by the number of infections, the viral population had begun to reach an initial steep point of its growth curve.186 Deaths began to increase. By August one thousand people had died of the disease. By October that number had risen to three thousand in the three countries. By December it had surpassed five thousand. The doubling rate of the viral population continues to increase. This makes it progressively more difficult for health-care workers to manage the epidemic.
Ebola is most contagious (at its highest level of “virulence”) when the host becomes a corpse. Virions are most abundant in the pools of body fluids that collect in the dead individual (blood plasma, lymph, saliva, urine, and so on). In order to manage this disease, careful stewardship of the pathogen’s population is necessary. This comes from the workers doing the burying and containment of the infected corpses. As the doubling rate of infection increases, the workers may become overwhelmed. As of December 2014, the UN hoped to contain the virus by safely burying at least 70 percent of the dead in Sierra Leone and Liberia. The actual numbers are closer to 23 percent in Liberia and only 40 percent in Sierra Leone. This means that most of the diseased corpses are not being isolated, which leads to more infection of healthy unprotected bystanders. Many of these infections occur at burial rituals, based on long-standing cultural practices, in which family and friends touch the corpse before it is buried. If the knowledge of viral population growth and its effect on the rising death toll is not shared, decisions about rituals and isolation of bodies will continue to hobble the containment of this disease.187
Many of us have older friends or family members who contracted polio, whooping cough, or measles in the early to mid-twentieth century. These diseases of the past, and the Ebola outbreak going on currently, should be reminders that only through population management—containment of bacterial, viral, and other pest populations—can we hope to maintain the health of our own species. It is foolish to think we can vanquish any of them. Populations persist, and these dangerous ones are waiting in the wings for another opportunity to expand their range.
All biological and environmental threats to the well-being of our population require constant stewardship. Stewardship is not a simple one-step operation, such as pouring weed-and-feed herbicide and fertilizer on your lawn twice a year. In order to be good stewards of the biosphere, we have to foster an ongoing commitment to learning about other species. We need to find an answer to the fundamental question: What is the modern human ecosystem? before we can address how to manage the ecological interrelationships we have with other species. Stewardship refers to active management of those species and careful monitoring of ourselves in the context of a functional biosphere. I have faith that humans will—like most populations—persist through the hardships of the future. However, the grim possibility that our descendants will, like the beech and the chestnut, survive only in small, isolated populations, fearful of one another, merely eking out a meager living on their own small patch of land, goes against every hopeful bone in my body.
Homo sapiens is remarkably persistent. We’ve survived diseases that decimated continents, wars that wiped out entire generations, and natural disasters that obliterated whole countries. The worst human-caused impacts seem to kill off at most 50 percent of the population, as we will see below. Extinction, however, would be total. It is primarily associated with large-scale environmental climatological events. In the past, species have been wiped out by climate changes caused by unforeseeable events—meteor strikes, or vast amounts of atmospheric poison caused by volcanic activity. We are the first species that has been able to monitor and modulate the waste products that affect our environment. This means that we are also the first species that has a chance to reverse course and prevent hundreds of millions of climate-change-related deaths. In order to do this we need to learn to care about people, populations, and environments that seemingly have nothing to do with our own individual lives. A shift in focus, from individuals to populations, is the crucial factor that will bring this about.
I don’t think that indulging in an overly emotional reaction to human tragedy is helpful. This does not mean, however, steeling oneself against compassion, or forgoing sympathy. There is plenty of suffering to be mindful of. Instead what is needed is a rational sense of empathy. Empathy means that we can understand another person’s pain by extrapolating from a painful event in our own life. I am aware that I can’t alleviate the pain for most suffering individuals in the world, but I feel motivated to do something about it. For instance, empathy motivates me to take action by raising awareness about the human condition in my songs, books, and lectures.
Most human suffering has identifiable causes. Our civilization learned how to avoid many of these dangers as it grew, passing on that knowledge to later generations, and we have now ameliorated many of the most insidious problems. Many diseases, weather disasters, and conventional wars, have, for the most part, been kept at bay in the Western world by modern technology, sanitation, and diplomacy. None of these advances is guaranteed to stay in place permanently. Populations are in a constant state of flux; and we are foolish to declare victory prematurely. This is especially true where we began this book, in the realm of conventional warfare, defining and trying to eradicate so-called enemy populations.
At certain times, such as during natural disasters, famines, or disease outbreaks, our human capacity for empathy is heightened. But sometimes caring should be balanced by a distanced analysis. It’s this attitude I take when I consider that most newsworthy tragedies don’t actually have a devastating effect on the standing size of the human population. We, as rational thinkers, have to acknowledge that our globe is interconnected as never before. Therefore our human population is nearly panmictic, which means that anyone has the potential to mate with anyone else on the planet. True, there is less likelihood of a villager in Africa mating with a farmer in Nebraska than of a Wall Street trader mating with a Chinese business executive. But there are plenty of examples of poverty-stricken foreigners from the Third World marrying Westerners and having kids who are brought up far from their parents’ original habitats. We can thank intercontinental airplane travel for that.
Because of this, and because we are at such a steep phase of the exponential growth curve, the human population is at once relatively impervious to local “tragedies” and at the same time capable of producing more variations of new people to replace those who die in such catastrophes. In short, the rate of replacement is what a population scientist focuses on, and it’s this perspective that I consider most prudent. However, most human-interest drama causes us to focus less on the rate of replacement and more on the loss of individual lives.
As one example, consider this. The largest single catastrophe from a weather-related incident was the Bhola cyclone of 1970 in Bangladesh (then called East Pakistan). This storm killed an estimated five hundred thousand people, many of whom were swept away by huge storm-surge ocean waves (aka tidal waves or tsunamis) and were never recovered. A similar tragedy happened more recently. In 2008 Burma (now Myanmar) experienced a cyclone called Nargis, that killed around 150,000 people. This cyclone sent a huge storm-surge wave twenty-five miles up the Irawaddy River and decimated towns along the way. Most victims were washed away in an instant. On the day after Christmas 2004, an earthquake brought equal destruction to residents in Indonesia. The quake, although registering as the third-largest Richter-scale reading in history (9.3), was not the killer. Once again, it was the storm surge, this time caused by the shifting ocean floor that cracked apart from tectonic forces. A wave nearly one hundred feet high spread outward from the epicenter in the southeastern Indian Ocean. Within hours this wave struck land and nearly 250,000 people lost their lives in Indonesia, Sri Lanka, India, and Thailand.
These events are heartbreaking. When tens of thousands of people die in one short burst of “nature’s wrath,” we naturally feel that our population’s future is vulnerable. But if we take the population scientist’s approach to these events, we see that they don’t actually predict anything about the health of our species at large. In fact that might be the disconnect, and the greatest challenge to our ability as stewards of the planet. How can we manage our species if we get caught up in these horrific disasters? I’m not sure the answer is easy, but certainly the facts are sobering.
In Japan the birth rate in 2011, the year of the 3/11 Tohoku earthquake and tsunami,188 was about 7.3 per 1,000 people. The disaster may have removed twenty thousand people from the Japanese population, but from new births, roughly twenty-six thousand were added to the population every month that year. So in one sense, though a very callous one, it took only about twenty-two days for the Japanese population to restore its population size . Given the rate of population growth in the northern Bay of Bengal at the time of the 1970 Bhola cyclone, it took the residents of that region only two months to replace the numbers of those killed in the storm with new births.
So, if natural disasters don’t do much to dent the human population, what about warfare? Certainly we’ve heard plenty of stories about the vanquishing of previous civilizations by dominating armies and occupations. And in fact the numbers of casualties from modern warfare are staggering. Until the twentieth century those killed in individual battles by “conquerors” in history made up relatively small numbers, on the order of tens of thousands at worst—similar to some of the natural disasters just described. A notable exception is the Mongol conquests of Genghis Khan in the thirteenth century. Inspired by territorial imperatives, Khan and his men slaughtered nearly forty million people, who stood in the way or resisted the spread of Mongol culture. Considering that the world’s population was only around 400 million at the time, this means that Genghis Khan was responsible for killing one in every ten people alive! This may well have caused a population bottleneck, eliminating a sizable portion of the standing diversity at the time. Khan and his men, however, also raped many of the women along the way, thereby unwittingly assimilating the very populations he hoped to vanquish. And through it all, the world population continued to grow.
By the middle of the nineteenth century, there were roughly 1 billion people on the planet. During that century in China, the Taiping Rebellion saw roughly twenty million die from warfare, while more than five hundred thousand died in Spain in a series of civil wars. Some 750,000 people perished in the American Civil War. These wars merely set the stage for what was to come in the twentieth century.
The most brutal wars came as the twentieth century matured. Roughly fifteen million people lost their lives as a result of the First World War, and since the issues that caused it were never successfully laid to rest through diplomacy, World War II rose up amid its ashes and caused the greatest loss of life ever witnessed from human conflict. Between sixty and eighty million humans died during that war in the years 1939–45. In China and Russia, civil wars took place between the two world wars, resulting in the deaths of roughly twelve million people. It’s normal to wonder what effect this loss of life had on our population structure189 (I’ve always maintained that the world lost its mind in the two or three decades before I was born.)
At the end of World War I Lenin called for a European revolution based on socialism and meant to establish communist communities of peasants and workers. At the same time Woodrow Wilson proclaimed that a League of Nations, headed by the United States, should be based on democracy, not communism (the United States eventually failed to join). Russia and the United States, allied in the fight over Europe, harbored opposing, incompatible ideologies that remained intact through another global conflict, World War II. At each step of the way violence made citizens miserable or worse, while the promises that came from the war’s architects always fell short of fulfillment. “Victory” was felt only in the relief of misery, but not in the vanquishing of some enemy population.
Nearly half of the sixty to eighty million people who lost their lives in the Second World War were civilian. The end of the war brought “peace” in name only, as Russia and the United States had vast ideological differences on how the world’s states should comingle. It took almost fifty years, but in the end the Soviet system gave out (in 1989–90), and today democracy is not only the mainstay of the Western world, but it has displaced imperial and dictatorial regimes, and has been an intrusive partner of socialist governments worldwide.
But socialism wasn’t vanquished, either as an ideology or a policy. Congress is currently debating the very same issues that Russia and the United States debated in 1918 (namely the role of centralized government in provision for and procurement from its citizens). In other words the global wars, the carnage and suffering, of the last hundred years ended without an ideological conclusion to bring disparate populations together. It’s as if warfare in the twentieth century and even today were just part of a never-ending philosophical debate. Yet despite all these senseless deaths from war, the global population of humans continued to increase, from about 1.6 billion in 1900 to about 2.5 billion in 1950, to today’s 7.1 billion. It would take a lot more than hundreds of millions of deaths from warfare to vanquish our population.
Unlike typhoons, earthquakes, or other natural disasters, war is predicated on failed diplomacy. It can be prevented! But, more important, war can be understood. That is to say, the way we treat human warfare in our historical narratives can be rewritten to be more consistent with how we explain the evolution of organisms. Populations, by their nature, come to coexist with much difficulty; many, many individuals will die in the process of assimilation. War doesn’t have to be this way because we, unlike animals and other species, can put ideology aside if we value the lives of individuals and the potential benefits they bring to our population’s future. No other species has the ability to do this. We should be able to foster a more harmonious cultural mélange using policy and reason, without the extreme violence and upheaval caused by conventional warfare.
The brutality of human wars is only one of two major hurdles we need to clear in order to achieve a satisfying shift in focus away from individual suffering toward that of true population stewardship. The other is the burgeoning environmental crisis we are busily creating for ourselves. If we can learn to manage everything from wild species to microbe populations, we should be able to create a global, sustainable environment for ourselves.
All extant organisms have the tendency to coexist. Extinction takes place despite, not because of, this coexistence. So it’s crucial that we recognize the following: Nearly all mass extinction events correlate with some kind of atmospheric or oceanic disturbance. Our own species is not immune to extinction; if we wish to persist we need to look at our predicament from a scientific perspective, just as we might consider the plight of any endangered animal. Or, as a biologist would say, we need to figure out a way to preserve our longevity as an evolutionary taxon.190 The recognition that our atmosphere and oceans are being fouled by our own industry means that we are not only unscientific but supremely stupid if we don’t do everything in our power to clean them up. This will, as a first requirement, entail widespread education about the atmosphere and the oceans, bolstered by strong pollution laws and the spread of environmental ethics.
Earth history has to play a central role in the new narrative of the twenty-first century. All discussions of sustainability ultimately come down to expectations with respect to the environment. The rocks beneath our feet record a long history of environmental change and contain correlated atmospheric signatures. They tell us that mass extinctions are accompanied by climatic perturbations. Human hunting or overuse of natural resources only exacerbates the “natural” process of extinction, especially if the species in question is already out of equilibrium with its environment and its population numbers are dwindling. If we are serious about being stewards, therefore, we have to understand our role in disturbing the environment. This ultimately boils down to what we consume, what we throw away, and the by-products created in the process.
In early Earth history it was an easier equation than it is today. Those populations that first inhabited the planet were cyanobacteria or something closely akin to them, around 3.5 billion years ago. They consumed water and CO2 and produced oxygen as a by-product. At first, this oxygen was sequestered in sediments that rusted (oxidized) and formed great deposits called banded iron formations (BIFs). Also called “oxygen sinks,” these sediments were soon unable to absorb the excess oxygen produced by rapidly proliferating populations of photosynthetic organisms, and it began to pervade every part of the primitive oceans. So much oxygen was produced, in fact, that it created a crisis in the atmosphere and oceans: too much oxygen. Oxygen is toxic to most organisms, and much of evolutionary “innovation” has been devoted to dealing with this reality by chemical means called “antioxidant molecules.”
Had not the earliest life-forms evolved a means of protection, they would have succumbed to oxidation poisoning from their own waste products after sedimentary oxygen sinks had been used up. Today the cells of many species are surrounded by walls made of cellulose (plants) or peptidoglycan (bacteria) as a protective layer against the damages of atomic dismantling from oxygen. More effective yet, antioxidant molecules were an early evolutionary innovation of photosynthetic cells. They act as cellular oxygen sinks. In the case of animal cells, these substances are contained in small chambers inside the cytoplasm called peroxisomes. Peroxisomes contain hydrogen peroxide, a molecule found in almost every cell that comes into contact with oxygen. The ubiquity of this molecule suggests its crucial status. It likely took hundreds of millions of years to evolve, but hydrogen peroxide contained in peroxisomes was the result of the atmospheric buildup of oxygen. The evolution of this oxygen-absorbing organelle may have begun around 2.1 billion years ago, and it might have been the defining innovation that led to the eventual evolution of all the familiar kingdoms of life on the planet, including fungi, plants, and animals.191
Peroxisomes may have been the single most important player in the early Earth’s oxygen toxicity crisis, which began about 2.1 billion years ago. Microbes that contained these organelles (certain primitive eukaryotes) or those that could protect their cell contents by surrounding themselves with some kind of cell wall (peptidoglycan in some prokaryotes) were safe. But most cell biologists believe that there was a mass extinction at this early stage of the biosphere. The majority of cells and primitive colonies could not withstand the atmosphere and aquatic environments because they were quickly being poisoned by oxygen from photosynthesis. In other words these early prokaryotes were the first populations to establish the tradition of polluting the atmosphere due to careless overabundance.
Although the buildup may have been gradual, eventually all organisms on the planet became extinct except for those that had some kind of antioxidant mechanism to contend with the toxic environment. Some scientists posit that the first mass extinction on the planet was in response to this “great oxidation event”—the buildup of oxygen from photosynthetic microbes—during the Precambrian. There is a certain amount of irony in the fact that even the very first living cells on the planet eventually caused their own extinction by changing their environment.
We don’t have to look that far back in history to see life-threatening atmospheric perturbation; we are experiencing such an upheaval today. But it requires a shift in focus to recognize it. Just as in the stupidity of seemingly endless cycles of warfare in human history, we, like all organisms of the biosphere, blindly fall victim to our own exuberance of environmental overexploitation.
Global warming has become a politically charged discussion that divides scientifically minded citizens from conspiracy theorists and their advocates. The former, led by an international group, the IPCC,192 maintains a staunch position that CO2 from human activities is drastically affecting global warming. Hundreds of top scientists, performing ongoing research in chemistry, geology, atmospheric sciences, and biology, issue frequent reports on the state of our atmosphere. This group is counterbalanced by citizens who view science and global warming as a conspiracy to mislead the public. Many of those fueling the flames of doubt against scientists are industrialists, representatives from the coal and gas industries and the billionaires who make their fortunes from the unrestrained combustion of fossil fuels.193
There is no doubt that carbon dioxide in the atmosphere is correlated with Earth temperature and it has been so for most of Earth history.194 The degree of warming caused by humans in the current rise in atmospheric CO2 is debatable, but certainly more of it in the atmosphere means adding to, not detracting from, our woes of higher global temperatures. Whenever glaciation has predominated on our planet—and we are in a relatively cool phase currently, although much warmer than it was 12,800 years ago—there is an associated historical signature in rocks or ice cores that indicates low levels of CO2 in the atmosphere (lower than around 500 parts per million). In 1860 the atmosphere contained roughly 280 ppm, and today it has risen rapidly to around 380 ppm (about a 36 percent rise). This is due to industrialization during that time span.
Whether atmospheric CO2 causes global temperature to rise directly—as in its reflection of infrared radiation—or indirectly as a correlate of other factors, there is no denying that it is a potent greenhouse gas that needs to be closely monitored and regulated by environmental policies. If you’re not alarmed by the catastrophic weather-related disruptions to human health and welfare that are reported daily, then perhaps you should be alarmed by the drastic tornado activity in the Midwest (where warm, wet air of the midcontinental United States collides with cool air coming in from the West), or the nearshore coastal communities that are progressively becoming inundated at the current rate of 1.5 inches per decade, or the melting of glaciers in Antarctica and Greenland, or the measurement of global temperature in August 2014 as the highest ever recorded.195 These issues reveal that we are in the midst of a global climate change. If our ethical objective is to be good stewards of the planet in an effort to avoid human extinction, then our greenhouse-gas emissions should take center stage in all economic and social discourse. In other words our human population wars are ultimately at the mercy of the climate. If we successfully shift our focus to the most pressing environmental concerns—oceanic and atmospheric health—we will alleviate strife between all groups because we will have to cooperate to overcome such global-scale problems.
As I’ve shown throughout this book, Earth’s history is an episodic sequence of population wars. We are, as Shakespeare famously wrote, actors for whom “all the world is a stage.” It’s just that none of us gets that much time in the spotlight in the drama of evolution. Our individual lives are so short as to be almost insignificant—even the lifespan of a species is relatively brief in relation to the time frame of geologic history. Every epoch of Earth history is defined by species of fossil organisms that failed to live on into the subsequent period. For instance, the Frasnian-Famennian boundary divides the Late Devonian Period in Earth history (about 372 mya). On either side of this stratigraphic boundary are fossils representing vastly different ecological communities that were relatively intact for about ten million years. During the Famennian Age, the younger of the two, tetrapods first evolved, a distant, four-legged human ancestor we share with amphibians. No true tetrapods existed prior to this in the Frasnian. Of the fish that occurred in the Famennian, all had ancestors in the older Frasnian Age, but those ancestors were all extinct. They didn’t make it to live among their descendants in the Famennian. There was nearly total loss of jawless fishes, the most primitive members of our subphylum, Vertebrata.
I point out this boundary not because of its significance, but rather to use it as a representative of hundreds of similar such formal boundaries recognized by paleontologists throughout the fossil record. Every major division in the long record of Earth history is subdivided by these smaller boundaries. The thing to keep in mind is that they are all defined by faunal turnover (or floral turnover, when you consider plant communities). That means that every ten million years or so there is a significant-enough difference in the communities of species alive at the time to warrant a new stage in the formal classification of evolutionary history.
Because of this fossil evidence I prefer to see evolution as a sequence of generally disconnected episodes of coexistence rather than as a smoothly branching, graceful “tree of life.” The episodes are distinct; the species that coexisted during the deposition of one geological stratum are different from those that coexisted in the subsequent geological era. Yet there is a connection, even if the characters have all changed from one episode to the next. In all of Earth’s historical stratigraphic subdivisions there were communities of species that depended on one another and reached some sort of equilibrium, a state of ecological balance. It can be disrupted, such as in times of environmental crisis, but eventually new equilibria are established and life goes on for those populations that are lucky enough to make it to the next stage.
Each tick of the geological time scale brings countless extinctions; in fact extinction in Earth history is as common as warfare in human history. It’s these repetitive sequences of tragedies that we use to calibrate life on Earth. Consider one of countless examples, from a slice of Earth’s rock record that I studied as a graduate student, the Ordovician Period (485–444 mya).
Climate change affected the Ordovician biosphere in a number of ways. Glacial sequestering of water (freezing on continents) meant there was less water in the ocean basins, which caused exposure of the continental margins. These were, as today, nearshore reefs, precisely the areas of the greatest biological diversity in the ocean. At this time in Earth history there was no terrestrial ecosystem as we know it today. Neither plants nor animals had evolved on land yet. Habitats of nearshore marine organisms, once bathed in shallow water that received nutrient runoff from the continents, became flooded with harsh sunlight, exposed to cooler temperatures, and simply dried up. By the end of the Ordovician, there were 85 percent fewer species than were alive in the middle of the period. Some of the most popular fossils for collectors, trilobites (those flattened, insectlike creatures with greater than twenty pairs of jointed legs), lost many of their species, as did the clamlike group called brachiopods, and the clams themselves, the Bivalvia. Tinier creatures than these, viewable as fossils only with microscopes, which resemble minuscule branching woody plants—but are actually animals—the graptolites and bryozoans, also died out en masse. Perhaps the most familiar organism to go extinct at the end of the Ordovician were certain types of corals.
Coral reefs are the most biologically diverse ecosystems in the oceans. They are nearshore communities of species that live on, inside, and around secreted skeletons of stationary animals. Usually when you look at a coral in a museum or collection, you have a sample of only its skeleton, since the soft tissue has decomposed. The first thing you notice is that it’s composed of a hard, limestone-like material that is pockmarked with cavities. Inside each of these cavities is where an individual animal lived. Corals are colonial populations all living together in this combined skeletal structure. Over time new generations build up on top of previous ones. Billions of individuals combine to form the framework of coral reefs, and a single fused-together colony can extend over hundreds of square miles.
Mass extinctions in Earth history have always destroyed the world’s reefs. In the Ordovician Period, the dominant reef species (aka, the framework species) were stromatoporoid sponges, flat matlike organisms with multiple layers of sequentially deposited skeletal calcium carbonate (calcite or CaCO3). Another reef framework builder at this time was an alga called Receptaculites sp. This organism looked like the head of a sunflower, and like the sponges, also deposited calcitic skeletons. These were accompanied by a group called Rugosa, or “horn” corals. Much different in anatomy than our corals today, they performed the same ecological function—catching tiny prey using specialized stinging cells or trapping free-floating plankton in the nearshore environment, excreting nitrogenous waste, and building calcitic skeletons that contributed to the framework of the reef.196 All these groups formed the framework of a huge and complex biological community. When they went extinct due to climate change, glaciation, and the disappearance of their nearshore environment at the end of the Ordovician, all the other species that depended on them also went extinct. When reefs die, it is not simply the loss of a single coral species, it is the erasure of an entire web of coexisting animals, plantlike algae, protists, and bacteria.
Fossils don’t provide the only window into mass extinction. Thanks to geochemistry we can measure the signature of ecologically significant elements in rocks that indicate changes in the primitive atmosphere. Specifically, carbon can be traced in Earth history as never before. We can now put a correlative atmospheric chemical stamp on the fossil record. Elemental variations (called isotopes) tell a story about the environment that accompanied the mass extinctions.
In each mass extinction, there was a rapid change in atmospheric carbon.197 Most commonly this was due to rapid fluctuations (usually an increase) in atmospheric CO2 levels. In fact, after the extinction of reefs during the “Big Five” mass extinctions, the Ordovician being one of them, it took roughly ten million or more years for new reef communities to become established. These are known as “reef gaps” in the fossil record, and they indicate voids of biodiversity inflicted by the environmental aftereffects of climate disruptions. Carbonic acid, created by high levels of CO2 in the atmosphere, enters the reef environment as rain. If sufficiently high levels are encountered, the ocean can’t absorb or “buffer” the acid, and the water chemistry is affected (lowering the pH level). This is just one of several environmental factors, correlated with the carbon cycle, that cause reefs to die. Algae that secrete calcifying cement are also affected by acidification. Without the physical process of mineralization created by organisms all working in synergy, the reef community is doomed. Reefs, like forests of the ocean, are, and always have been, the bellwethers of ecological health, and today’s reefs are showing signals of stress.
Recent monitoring studies have found that reefs worldwide show between 27 percent and 35 percent dead coral polyps (the tiny animals that live on and secrete the framework of the reef).198 Meanwhile, nitrates from agricultural runoff end up in the nearshore and cause a huge increase in algae. These populations encrust on top of the reefs and destroy the living polyps. Furthermore, warmer surface waters (from increasing greenhouse conditions), cause “bleaching” of the corals, which eventually destroys the reef’s vitality and causes depletion in the entire community of reef species. This is particularly relevant to the theme of this book because it shows how environmental perturbation causes a breakdown of symbiosis.
Arguably the most important element in today’s reef ecosystems is a genus of photosynthetic algae (or protist, depending on the classification) called Symbiodinium. This genus is a member of a larger group of single-celled, mostly free-swimming algae called Dinoflagellates. Individuals of the tiny single-celled Symbiodinium live in huge numbers, up to one million of them in a single cubic centimeter of coral polyp tissue. They form a mutualistic, symbiotic relationship with the corals, and contribute to the growth and secretion of the reef’s carbonate framework.
Beginning their lives as free-swimming organisms, these tiny dinoflagellates are taken up through phagocytosis by individual cells of the coral tissue. Once inside the coral tissue, Symbiodinium begins its mutualistic relationship. Both inorganic and organic molecules are exchanged between both partners, host coral and mutualist dinoflagellate. This means that both populations continue to grow, replicate, and thrive in the presence of the other. Each partner in the symbiotic relationship brings valuable resources to the other. The lovely colors of corals are due to varying amounts of photosynthetic pigments contained in their symbiotic dinoflagellate population. Corals are not photosynthetic organisms, but they derive benefits from the sugars and other compounds produced by photosynthesis due to their symbiotic dinoflagellates.
When waters become polluted, or when temperatures rise in the surface layers of the ocean, corals become stressed. The first action taken under such conditions is an expulsion of their symbiotic partners. It’s almost as if Poseidon puts out a clarion call for all organisms to “save yourselves” in times of ecological distress! In reality, bleaching is due to the lack of symbiotic algae, and this indicates that the coral is damaged. What’s worse, expelling the dinoflagellates only makes them less healthy. Corals begin to starve when they expel their dinoflagellate residents. Bleached coral is not dead per se, but it is not actively growing or thriving either. Numerous reef species that depend on coral for their sustenance, such as “grazing” fish and mollusks that eat the polyps, disappear or begin to starve. In short the disappearance of the dinoflagellates sets off a chain reaction that depletes the entire community of reef species. The best estimates indicate that today’s reef communities are disappearing. Some of the reefs in the Florida Keys have lost 90 percent of their coral population in the last forty years.199
Less than a call to action for reefs specifically, this data is most alarming because of what it says about the environment that we have created. Using the history of extinct reefs as our guide, we can already see the beginnings of a modern-day mass extinction upon us. Shifting our focus toward that of population stewardship might save the reefs, but more important, it might be just the thing to save our own species from this mass extinction.
The time frame of extinction is not easy to grasp. Only very rarely do examples like the dodo present themselves, which, as mentioned, went extinct in a relatively short period of time and was recorded in journals as it happened. Yet extinction is a fact of the fossil record. This record is imperfect, which means that it’s too coarse grained to reveal the slowness of population decline. Think of the fossil record this way: If an inch of strata takes ten thousand years to deposit (as is reasonable to assume in layers of mudstone), that means that finding a fossil, say a snail shell, in one of those layers reveals one species alive during that particular span of time. If no more fossils of those snail shells are found in the overlying layers, all we can say is that somewhere in the span of ten thousand years, the species became extinct. Maybe it was a slow death of the population, maybe it was instantaneous, but because the sample size of the fossils is so small, and the time span between strata so long, we cannot pinpoint the exact time or rate of the extinction. Often, due to the vagaries of the fossil record, we deal with millions of years rather than tens of thousands.
So, if we consider the coarseness of the fossil record, we have to accept that extinctions might be slow. We know, for instance, that our own species has existed over a time span of roughly two hundred thousand years during the Pleistocene Epoch of Earth history. Since that time there have been numerous notable extinctions of large mammals that comprised a community often referred to as the Pleistocene megafauna. The La Brea tar pits in Los Angeles, one of the richest fossil sites in the world, contains a great sampling of many of their remains. One of the most important aspects of the La Brea tar pits is the evidence that humans lived alongside these giants of the past. Among the strange species is the giant ground sloth, genus Paramylodon. This beast weighed fifteen hundred pounds, could reach up to branches nearly twenty feet high, and ate rough vegetation and leaves. Nothing like it exists today. Our ancestors also lived alongside the saber-toothed cat, genus Smilodon. Larger than any lion alive today, this ferocious predator hunted huge elephants (mastodons and mammoths) that roamed North America and Asia. Both the saber-toothed cat and the elephants are now extinct. The short-faced bear, genus Arctodus, is another veritable La Brea giant. Standing five feet at the shoulders (when on all fours), this bear weighed nearly one ton and was as ferocious in its predatory behavior as any grizzly alive today. But, like its cohorts in the Pleistocene megafauna, it is not to be found anywhere today. Likewise for other huge mammals with whom our ancestors shared the late Pleistocene landscape: the ancient camel, genus Camelops, the huge dire wolf, genus Canis, and the seven-foot-tall ancient bison, genus Bison. This is just a mere sampling of the many species that made up the Pleistocene megafauna, but all are extinct today. In fact all large mammals of the Pleistocene megafauna died out by eleven thousand years ago. Our own species, however, has continued to expand its range and increase its population size since that time.
A paleontologist of the future might discover sediments that contain these huge fossil mammals commingled with bones from modern humans. The sediments filling the Los Angeles Basin are slowly piling up with each rainstorm that washes down the canyons. All the debris from modern humans, including their remains from the nearby Hollywood Forever Cemetery, might be washed together with the fossils from the La Brea tar pits into one great sedimentary unit somewhere just offshore, perhaps in Santa Monica Bay. This sedimentary layer, containing a mixture of our modern human remains with bones from La Brea tar pits, might get quickly covered by sediments washing down off the Santa Monica Mountains, whose canyons empty directly into the sea.
In this case of a hypothetical mixture of “young fossils” from the La Brea tar pits with modern bones of today, there would be no recognizing the megafauna as distinct from modern man. The stratigraphic horizon would be a jumble of bones that would all seem to have lived contemporaneously. The paleontologists of the future would have no other data than those allowing them to conclude that we modern humans lived alongside the Pleistocene megafauna. There is truth to this conclusion because we already know, from other fossil evidence, that humans lived alongside the megafauna. But what this possibility says to me is that this stage of Earth history is still ongoing. The Pleistocene extinction might still be under way, and we are living to witness it.
The endangered large mammals of today, the polar bear, cheetah, elephant, rhino, or timber wolf, for instance, when viewed in the light of the already dead megafauna, and coupled with the data from the declining vitality of bleached corals, tell me that there is a good reason to view extinction as a long-term phenomenon, and consider that we might become a very widespread and abundant fossil as part of this “sixth” mass extinction.200 The fact that we continue to increase our population, however, is both a blessing and a curse. It means that we are doing something right in the midst of all this extinction of large mammals. But it also points out how crucial it is to heed the examples I’ve used throughout this book to remember that humans are subject to the same laws of population growth, equilibrium, and extinction as other species, if we don’t actively manage our evolution.
The mention of managing evolution in humans leads immediately to the fear of eugenics, the misguided attempts of geneticists, particularly in the early twentieth century, to change the human race through breeding. Led by Charles Darwin’s cousin Francis Galton, an otherwise gifted mathematician and statistician, an entire cadre of intellectuals, geneticists, and politicians agreed that one of the great imperatives of mankind should be the elimination of harmful and less-desirable genes from our species. “I … maintain that it is a duty we owe to humanity to investigate the range of that power [of breeding in humans], and to exercise it in a way that, without being unwise towards ourselves, shall be most advantageous to future inhabitants of the Earth.”201 There is an undeniably hopeful tone to Galton’s mission. Just as the practice of animal husbandry changed livestock into improved races, he and his followers believed that through scientifically rigorous social programs, the human race could be improved. Since Galton’s main focus, originally, was related to breeding for genius, it should come as no surprise that his followers devised plans, not altogether pernicious, to distinguish between those of low and high mental ability.
Sadly, this mission, begun in 1883 with Galton’s coining of the word “eugenics” (meaning “of good stock”), devolved into a misguided scientific agenda after genes were discovered around 1900. The pervasive belief among geneticists of the early 1900s (who at the time knew nothing of the genetic complexity of human intelligence) was that “feeble-minded” people carried bad genes. If such people could be prevented from passing those genes on to future generations, they thought, the stock of the human race would improve. So, much energy and expense was wasted in measurement of races, classes, occupations, and abilities, in an attempt to quantify their degree of intelligence. In the United States this led to a tragic program of forced sterilization of the “feeble minded,” justified by law, first in Indiana in 1907, and eventually ratified by the Supreme Court in 1927 (Buck vs. Bell).202 Called “genetically unfit” under these laws, an estimated 65,000 people were sterilized without their consent in the United States in the first half of the twentieth century.
The idea that intelligence could be reduced to a single, measurable, quantity, based in the genes, was taken to extremes in those days, and scientists—particularly social scientists—applied the idea to an outdated scale of human races from the eighteenth century, placing Caucasians at the top.203 In more recent times the reflection of this racism, based in eugenics, has been espoused by those who promote the IQ test as the best way of measuring human intelligence. Intelligence is dominantly affected by culture and its impact on development of the brain, that is, neuronal selection. Unlike the genes, intelligence can, therefore, be changed dramatically during a person’s lifetime through education and new experiences. Thus intelligence is not a measurable genetic variant that is useful in characterizing racial differences in humans. As the geneticist Richard Lewontin succinctly noted: “The genes for intelligence have never been found.”204
The prevention of human breeding through sterilization is now considered a form of genocide, and it is condemned by all member nations of the UN. The belief in “improvement” of the human race is not generally considered possible, or desirable from an evolutionary perspective. First, it’s difficult to think of a trait that is universally considered “bad.” Second, most traits are linked to other traits, so getting rid of a so-called bad trait in a population might also affect the proliferation of a beneficial linked trait. But third, and most important, whatever we view as a bad trait is arbitrary, and should instead be seen as a variant. Variation is the raw material of natural selection. Who is to say that a bad trait today will retain its “badness” in the future, when conditions change? Even if we could breed “bad genes” out of our genomes, in a very real sense we would be short-changing future populations by removing variation, and thereby lowering their potential for evolutionary change.
With the outrageous failures of the early geneticists, one would think that the science of human improvement might have died a long time ago. Not so. Instead of government policies on breeding, however, today’s eugenics has taken on a new name: personalized genomics. Today individuals are given choices about reproduction that allow them to feel some degree of control over the future complexion of their family. These screenings have become commonplace for cancer and other diseases.
For less than one hundred dollars, any couple planning on having children can get a genetic screening, which is a complete readout of both partners’ DNA sequence. Within this sequence, specialists recognize gene variants (aka alleles), some of which might be detrimental if combined in a certain way with other gene variants. Through decades of accumulating genetic data, hundreds of genes are now known to correlate with various cancers and other diseases. If a specialist determines that both partners of the couple are carrying a disease gene variant, but not showing any signs of that disease, it is possible that they could remain healthy but give birth to a child who develops the disease. In such a case the couple might decide to forgo having a child.
This doesn’t sound like evolution management, but it is. If a couple decides not to pass on their genes, the future population will not inherit any of their genetic variations. Since our population is so huge, however, individual actions like this will probably not even make a dent in the future of our species unless they’re widely adopted. We cannot revert to the legally implemented genetic policies of the early twentieth century, even if we did universally agree that cancer genes are bad. Government mandates on breeding in humans are just too unsettling ever to be viable again. But I believe we can still manage the evolution of our species by paying close attention to the environment. It’s less of a question of population genetics and more a question of determining the limits of environmental parameters under which the human organism thrives, and then committing to maintaining ourselves within that range.
I’m a child of the seventies. As a kid I wore T-shirts that said, “Save the Whales,” “Save the Pandas,” or simply “Save the Planet.” My focus was on saving other species because we—Homo sapiens—didn’t seem at risk. I’m not so sure about that anymore. Now I think that when we talk about “saving the planet,” what we really need to think about is “saving ourselves as well.” I have friends who are such committed environmentalists that they think the best possible outcome is an Earth that has been wiped clean of human beings, where the natural world has returned to some kind of prehuman equilibrium. I don’t understand this idea; I don’t see Homo sapiens as being some kind of irredeemably flawed species. My friends who embrace these kinds of extreme ideas are against the destruction of anything in the natural world—other than humans. Their point of view, which I understand, is that enough of nature has already been destroyed. They believe that instead of indiscriminate destruction we must now embrace indiscriminate preservation. The problem with this philosophy, as pointed out earlier, is that it does not take into account the fact that we live in a world that is already disturbed.
Disturbed areas are vulnerable; and in order to maintain any kind of population balance you have to be willing to manage actively what gets to live and what has to die. Anyone who has tended a garden or mowed a lawn has done so without thinking twice about it. I do it routinely as a landscaper on my property in upstate New York. In fact some of my friends are surprised to see that I don’t hesitate to use the controversial weed killer Roundup to control unwanted invasives. This to me is less about supporting some supposedly conspiratorial multinational company (Monsanto invented Roundup), and more about population management or stewardship. Applying Roundup responsibly, in limited areas, during alternate growing seasons, is an effective and safe way to kill weeds and prevent incursions from invasive species. Almost everyone, from organic farmers to florists to national park rangers to golfers, agrees that invasive plants bring with them invasive animals, and all of them are bad.
We all have inherited a disturbed world in which our forebears have artificially created and exaggerated areas of ecological imbalance. Oceans are in crisis because of pollution, global warming, overfishing, rising acidity, and the great gyres of trash in the Pacific. Substitute a forest for an ocean and it is the same story—there is no going back to an older version of some idealized, natural, prehuman world. The only way is onward. We have to be active stewards of our environment and operate in a logical and rational way. I am incredibly sad that my large beech trees die at such a premature age, but that is the new reality of the arboreal world, and I have to accept it. Instead of lamenting the fact that I’ll never see a stand of healthy chestnut trees, I have to manage the populations that have persisted in their stead.
As a landowner, I have a say about what happens to my small patch of eastern hardwood forest. Legally I own that right, as well as the rights to any minerals underneath the forest. What I don’t own, in any logical sense, is the species themselves, or the ecosystem in which they participate. I have taken it upon myself, through a sense of ethical stewardship, to preserve as much of that ecosystem and keep it untrammeled as possible. Our elected officials and every citizen who consumes natural resources need to take the same responsibility. If they can’t do this by understanding the implications of science or by reflecting on facts of evolutionary history, then at least they can achieve this through understanding that they are dependent on other populations for their own well-being.
Having some control over the environment could rightly be seen as humankind’s greatest achievement, greater than walking on the moon, greater than the Internet, greater than modern medicine. I say this because dealing with environmental hazards is the one thing we share with every other population that has ever existed in nearly 4 billion years of Earth history. The earliest life-forms created atmospheric pollution that nearly destroyed them. Through the evolution of antioxidant molecules and other “strategies,” those hazards were overcome, but it took nearly a billion years. In a sense we are still contending with the challenges of the earliest population wars. From Earth’s most primitive organisms to us is a long, circuitous, line of descent, and we have ended up in the same predicament. Like our bacterial predecessors, we have unwittingly released poisons into the environment from our activities. Also, as seen in the early cyanobacteria, the effects of this pollution have altered the other species with which we coexist. For the first time in the history of life, however, we can break free from the unwitting poisoning of the planet because we have an evolved trait that they lacked: consciousness. Through the monitoring and control of production, consumption, and disposal, we can manage the evolutionary constraints to which other species must adapt.
Charles Darwin recognized that adaptation entailed two components: survival and reproduction. In order for evolution to occur, populations have to show variation of its individuals in their ability to contend with the environment (survival) and to leave more offspring (reproduction). For the first time in the evolutionary history of life, our species now has the ability to manage each of these components to some degree. We can sequence the genome of any organism, including our own, use biomolecules to cut out sections of DNA, splice them together, and manage their gene products (beneficial or harmful proteins). We can invent machines that create few to no toxic by-products for the environment. We can control other populations, from pathogens to household pests, by killing them, displacing them, or immunizing ourselves, as never before. We can even modify the genetics of food populations upon which we subsist (from fish to plants and everything in between). But what we can’t seem to do is shake the pervasive belief that a God or some other force is in charge of our ultimate destiny.
Those who believe that God’s hand guides everything in the universe are in the same nihilistic boat as scientists who believe that there is nothing we can do to prevent our imminent extinction. They both leave the destiny of our species in the hands of something over which we have no control—either a deity or a grim statistical probability based on other mammals’ longevity. I don’t identify with either of these groups. I’m a naturalist, and therefore I find solace in the facts of an evolutionary worldview, which teaches that nothing is predestined by a deity or by a static system of genes interacting with the environment. The biosphere is in constant flux. I believe that we have some control over both of the major components of evolution, survival with respect to the environment, and reproduction of our own as well as other species. This is all the validation I need to come to the conclusion that humans can be effective stewards of the planet and thereby guide, however coarsely, our own microevolution.205
My view still leaves room for debates over ultimate fate. Throughout the course of Earth’s history, as we have seen, there are unforeseen tragedies that affect all species (mass extinctions). Despite much biogeochemical research and alarming preliminary data on mass extinctions, it is at least possible that we have no control over these catastrophic biocrises. If that is the case, and we cannot predict such large-scale depletions of biological diversity, I see no reason why a religious person’s position that “only God knows when the next mass extinction will occur” should not be considered at least equal to that of the scientist who claims “we cannot predict when the next catastrophic event will occur.” If, however, the data continue to accumulate showing that past mass extinctions are correlated with widespread and rapid swings in CO2, then we have another reason to abandon faith in all supernatural forces and accept our role as stewards of the environment. Knowing where we have control and admitting where we don’t are a guide to further research. Relinquishing all responsibility to some supernatural entity—fate or God—is hopeless.
Back home on the farm I see incremental improvements in technology that give me reasons to be hopeful. My old tractor is a 1962 Allis-Chalmers D19, and it burns gasoline. At the time of its manufacture very little concern was paid to hazardous emissions. Even though it has no emissions technology built into it, I don’t use it enough to make a significant dent in the atmosphere. I ride it only rarely. My newer tractor is a 2015 CaseIH 75C with a diesel engine that meets or exceeds the clean emissions standards set by the California Air Resources Board (CARB) and the U.S. Environmental Protection Agency (EPA). Our family car is the cleanest-burning vehicle on the road, with a high-efficiency diesel engine that give us forty-three miles to the gallon and whose exhaust is mixed with diesel exhaust fluid (DEF), which turns poisonous nitrous oxides (from normal combustion of fuels) into harmless, inert components of the atmosphere (water and nitrogen gas). As mentioned earlier, our house uses less water, is heated by less energy input, assisted by better insulation, and contributes less biological waste to the environment than any comparable house built within the last fifty years. All these are hopeful signs that incremental improvements in technology, coupled with greater public awareness, strict controls on industrial production, and enforcement of rigid and sensible environmental policies, could in fact lead to a better quality of environmental health.
A new era is creeping closer, one with perhaps zero harmful emissions, a new electric age for machinery and transportation. I look forward to riding my first electric tractor. This new technology, however, will be accompanied by a new way of looking at the world. This new worldview will carry with it a tacit understanding of coexistence, and a belief, although rarely acknowledged, that we have some control over the evolution of other species and our own.
Since we can monitor our environment like never before in Earth history, it should be our ethical imperative to try and maintain our species’ gradual evolution by controlling the correlates of mass extinctions, namely carbon dioxide. This may be only one of many yet undiscovered environmental factors that lead to widespread extinctions, and we have to acknowledge our limitations. There’s much that we cannot control—plate tectonics and its associated phenomena such as volcanoes and rifts come to mind. These processes cause greenhouse gases to be emitted into the atmosphere and oceans. Even though there’s nothing we can do to prevent volcanic activity, however, inventors and futurists are working hard to develop innovations that can absorb or reuse greenhouse gases from all sources, even volcanic, in order to make our environment more sustainable.206
Instead of fighting conventional wars to eradicate “evil” people, pathogens, or ideologies, we can instead shift our ethical focus to managing the most fundamental factor in our evolution, the environment. By doing so we will also affect all other species of the biosphere. We can either accept the truth that the human population has already mushroomed to the point of affecting nearly all other species on the planet, or hide from it and pretend that we are an isolated population living a distinct and parallel existence with no need to care about others. If we accept the truth, we will have gone a long way toward adopting a new, promising worldview that we have some control over the future of population wars.