Living things have something profound in common: They are all members of populations. In the past these groups were easy to tell apart. We humans considered some of them evil, some friendly, some wild and untamed, and some put here simply to serve our own selfish needs. It was easy to do so because we were ignorant. We didn’t have DNA tests to determine relatedness. We didn’t have electron microscopes to view microbes living inside us. We didn’t have radioactive isotopes to calibrate the time lines of migrations. And before about 1859, we didn’t have a narrative that linked all organisms as related by descent from a common ancestor.
Today, as more facts of history and biology have come to light, it’s much harder to draw a distinction between ourselves and those we consider “others.” This has created an intellectual crisis on many levels. How, for instance, do we make sense of the data that show humans are healthier when they have symbiotic bacteria living all over and inside them? This implies that our “selves” are actually shared communities of different species. What do we make of the data that show nearly half of our genome is from viruses? We carry around in each of our cells a habitat that allows viral replication as a necessary mechanism in the perpetuation of our own species. Another portion of the human genome is from Neanderthals, long-dead ancestors who could rightly claim us all as carrying on a portion of their genetic heritage. How can we reconcile this growing list of facts that testify to the ubiquity of symbiosis with the old narratives of competition and the “struggle for existence”? I think humans—particularly those who consider themselves paragons of an intellectually advanced, modern society—are having a hard time with it. Rapidly accumulating biological data are causing a dissonance of sorts between old narratives, based on ignorance, that run deep in the collective consciousness of all societies, and the new implications coming from recent studies. Scientists in general do a great job of collecting empirical data, but generally fall short in explaining the implications of their findings. Because of this, ironically, the delusions of modern Western society grow stronger in the face of increased knowledge. This is particularly evident in the narrative of war.
Why do we go to war? There are many answers, but part of this book concerns one of them: because war is an inevitable property of humankind, an inheritance from our distant ancestors, and as such it’s part of the interconnectedness of the biosphere throughout its long history. In other words, war is part of the symbiotic heritage of all life. Therefore we must look to coexisting populations and their interactions, historical as well as recent, human as well as other species’, if we ever want a serious answer to the question above. Behaviors akin to warfare are found in species across the entire spectrum of the animal kingdom, so it’s no surprise that humans exhibit them too.
Despite the ubiquity (and tacit inevitability) of population wars, a closer examination of some distantly related species reveals that there is as much interdependence in the biosphere as there is violence. The present is full of assimilations from populations of the past, and when we recognize some of these, it becomes apparent that there is hope for a less violent future for humankind. Hence the inevitability of population wars doesn’t mean that our future has to be violently catastrophic. In order to achieve such a result, however, humans have to come to terms with some basic facts of population biology, and we need to see a shift in consciousness away from some of our most deeply rooted prejudices and bad habits that have come from the rapid expansion of our species.
Today we exist as a globally distributed species with a particular nasty propensity: When we can’t see our enemies, we invent them. This illusory act of human nature allows us to justify attempts at eradicating, eliminating, or vanquishing other people or species. But such actions nearly always fail. A further goal of this book is to highlight those failures as a reason to take a fresh approach to one of the time-honored problems of human existence: defining “us” as distinct from “them.” This is ultimately a question of biology. How distinct are different groups of living things? I hope to show you that the answer is, A lot less than you previously thought. If I’m successful, you’ll see why we need to rethink the entire justification for war, not only the human military kind but also the thought of Darwin’s “war of nature” or “struggle for existence,” because war follows logically only from a notion of distinctness. If lines of distinction are blurred, whom (or what) are we fighting? In my view all types of conflict have to be recast in the light of coexistence and historical contingency. That is the message of this book.
We Americans love the war metaphor. As I write this, it seems that everyone is debating over how to deal with sinister forces that are attacking us on many fronts. We have the war on poverty, the war on drugs, the war on Ebola, the war on terror. Then there’s the war on the middle class, the war on workers, the culture wars, the war on women, the war on our kids, the war on family, among many others. Given all these deadly conflicts we’re engaged in, it’s no wonder that we’re considered a war-weary nation.1 We turn to narratives of “good vs. evil,” such as the Star Wars epics or the slew of Marvel comic-book movies, with almost religious fervor. These simplistic tales are emotionally satisfying to the general public, perhaps because they hark back to a time when it was easier to believe that the “bad guys” could be easily eradicated. Unfortunately, today we know better.
Are the enemies we face in these wars conquerable? The answer is no, but it seems that most people don’t know it. These trite phrases—“the war on…”—make for attention-grabbing headlines because of their emotional appeal, not their intellectual accuracy. Most people assume that there is an easy victory to every war. Whether it’s exterminating a pest from your house, eliminating a military force with a drone strike, or erasing an entire enemy population by dropping a nuclear warhead.
It should come as no surprise that none of those solutions have worked in the past, and they won’t work in the future either. Although in the short term an enemy might appear to be vanquished, in the long term that same population rebounds and—even if changed, perhaps—it eventually rebuilds its numbers. What we commonly assume to be wars are an elemental part of life, and the ebb and flow of population size is due to these conflicts. In fact they typify an ongoing biological drama that has been occurring since the origin of the biosphere, nearly 4 billion years ago. Populations have an inherent tendency to expand, and eventually, overcoming the constraints of their environment, they come in contact with one another. History is written and calibrated by these constant population wars that have occurred and that are still occurring today. Our only hope of mitigating entrenched misunderstandings, and in due course eliminating human wars—the actual military type that has caused so much needless suffering—is first to understand more about the natural world and the population interactions that typify other species.
Debates rage in our country over whether or not to ban all flights from Ebola-plagued countries in Africa, as if that alone could stop the “enemy” microbe from spreading. The idea is simple: Equate an enemy population of microbes with an enemy host population and vanquish both at once. As of this writing, more than 10,600 people have died from that disease in Liberia, Guinea, and Sierra Leone. Four people, on different occasions, have brought it back to the United States, and one of them died. But in the process the dead man infected two nurses in Texas, one of whom flew on a domestic airplane to Ohio, and may have passed the Ebola virus on to others. How this story plays out is anyone’s guess, but clearly we are witnessing a population war that is complicated. A microbe is increasing its species’ range. An ever-increasing panmictic2 human population is continuing to assimilate. And the American public—the vast majority of whom have a very low probability of ever coming in contact with an Ebola victim—are frightened beyond belief, and busy themselves with judgments about who is the enemy. Blame goes to the government—the CDC should have done more to stop the spread. Blame goes to the individual—the victim, now dead, should never have carried the disease to our country.3 Blame goes to the doctors—why did the Texas hospital staff allow a man infected with Ebola to leave the hospital instead of immediately putting him in quarantine? In fact there is enough blame to dole out to multiple enemies in order to justify eliminating all of them in this war on Ebola. But that won’t make the disease go away. Blame doesn’t solve population wars; it simply helps preserve—and foster—the illusion of an enemy.
Debates rage about the culprits in other diseases as well. Who will play the role of the victim and who the perpetrator in the war on AIDS or the war on tuberculosis? Is the flu shot an effective way to vanquish a persistent enemy, which attacks us every fall and winter? Are chronic intestinal ailments and digestive dysfunctions caused by the food industries? Or can those wars be won simply by eating more yogurt probiotics?
There is much to be considered with respect to human and microbe interactions. But I don’t want to give the impression that this book deals only with diseases, for there are many other types of population wars. Debates rage over the need for protection of endangered species. Livestock owners blame their lack of profits on the wolf, or the mountain lion, both majestic animals that live by eating other mammals, including domestic cattle and sheep. Protection of predatory species, and in some cases reintroduction of them into their former geographic range, now occupied by ranches, draws ire from property owners and applause from environmentalists (many of whom live far from the regions in question). Again we see a multidimensional problem that isn’t simple to convey in a catchy one-liner. The biological dimension of this population war—predators and their prey—has been going on since the origin of vertebrate animals at least 540 million years ago. The human dimension of this war is framed in terms of environmental health and restoration practices vs. the livelihood of farmers and ranchers and how public land should be used. Any change to one of these terms has a profound effect on the others.
Hawks and doves are the old symbols of the two sides in warfare. Today’s debates rage over the use of excessive force (hawkish behavior) by police officers against minorities, or by roving bands of well-armed government thugs, or by drone strikes to kill small teams of terrorists in areas heavily populated by nonmilitary citizens. Doves focus on the victims rather than on perpetrators. Body counts stick deep in their craws, causing resentment that often morphs into a misguided wish for retaliation. But those who favor revenge, like the general public ignorantly searching for an enemy during an epidemic, easily forget that population wars are, and have been, eternal because they are fought over the timeless constraints of resource utilization: They conveniently forget that every living thing requires resources. And that eventually populations will come in contact with one another because there isn’t a clean partitioning of each organism to a restricted patch of habitat. Resources commingle, and therefore populations are drawn together into a never-ending drama of coexistence.
Instead of an easy endgame to all these various population wars, it should be acknowledged that none of them are anything alike. Each interaction between populations is unique based simply on the extension of biology’s most fundamental fact—no two individuals are identical. No two populations are identical either, and therefore solutions to population problems require specific plans of action. But, as will be pointed out, any plan will end in failure if the naive notion of vanquishing enemies is at the forefront of one’s thinking. We will see that elimination of populations is difficult because of the one characteristic they all share: persistence. Populations are amalgams of previous populations. Usually a plethora of possible “enemies” from the past could be cited as participants in bringing about any given current population war. And therefore, simply not knowing who the enemy is could very well be our biggest failure in promoting warfare as an answer in the first place. Success will come from one tack only: long-term management of populations.
I began to appreciate population wars as a dominant theme in my thinking during my schooldays spent as a punk rocker. One of the common themes found throughout the punk subculture is a narrative of “them vs. us.”4 In Los Angeles, from around 1979 to 1981, it was very common for police violently to raid punk rock concerts, in full riot gear, batons swinging, because they believed that we were somehow destroying the fabric of youth culture and the hope of a clean-cut, organized future. The cops were spurred on in their disdain for us by songs that we sang in unison with our favorite bands: “California Über alles,” “No Values,” “Wrecking Crew,” “Fuck Authority,” and “I Don’t Care About You.”
I had no intention of overturning the status quo, simply reeducating it. I believed at an early stage that the “us” in punk referred to people who also felt like outcasts in the Southern California youth culture. Instead of nihilistic destruction, we believed in challenging the commonly held assumptions about what it meant to grow up in Los Angeles—that the only way to be cool was through surfing, skateboarding, hippy music, and smoking pot, and, as adults, the only way to be happy was to be rich so you could afford to buy more free time to surf, skate, and smoke pot.
I achieved early success as a songwriter, singer, and front man of Bad Religion. But somehow I never believed that it would last. So I remained committed to an intellectual pursuit of blending music with more “mainstream” academic work at universities. I immediately gravitated toward biology because of its focus on populations. All the fundamentals about natural selection and evolution—the foundations of all biology—require some sort of modeling about ideal populations and their interactions. This appealed to my identity as part of a subpopulation of outsiders—punk rockers in LA—and offered a promising way to make intellectual sense of that experience.
Biologists don’t actually measure entire populations in the wild; they sample them, and extrapolate the data to make theoretical predictions about how populations evolve and what brought them to a particular point in time. I learned that it wasn’t easy to idealize a population. I knew early on that punk rockers were more interesting than the stereotyped view that pigeonholed us as a population of kids who were useless no-goods, contributing nothing to our society. My punk friends in school were by and large the most intellectually motivated kids in the class, but the teachers by and large saw them as a subcultural aberration whose presence disrupted the tranquillity of the learning environment. These same individuals have gone on to achieve great success as adults—some of them are now both my friends and colleagues—with jobs such as academics, owners of media companies, movie directors, and record producers. I was drawn to using evolutionary themes as a songwriter, and mining the data of evolution to motivate my worldview. The story of any species’ ancestral lineage is multifaceted and surprising in many ways, just as human groups—such as punk rockers—don’t neatly conform to a predictable stereotype. Extrapolating from this realization leaves us with a profound conclusion.
Neither reprobate individuals, nor evil groups, nor species of predators, nor pathogenic microbes can be eradicated completely from our daily lives. Such a program of elimination will fail in the long term because of the persistence of populations. Rather than annihilation, it is tolerance and stewardship—providing resources and allowing some degree of freedom—that are required to coexist with other populations through time.
I find a lot of parallels in science and music, and I’ve dedicated my life to studying and practicing both. Music is what I do professionally. When I sing and play a song, there’s no ambiguity, no frustrations, just clarity in those moments of joy. I wish I could say the same for life science. Despite the huge compendium of accumulated biological data in the past one hundred years, we biologists only flatter ourselves with the belief that we are any closer to a unification of the field than we were in the last century. The field is more diversified than ever before, but this needn’t be a detriment. Rather than pretend that one unified theory underlies all of life science, I prefer to see the great accumulation of data as a broadening of the palette for creative scientific interpretations. Interdisciplinary syntheses often produce intradisciplinary squabbles, and that’s usually a good thing for all the participating academic fields. New knowledge comes from such frictions.
Punk tradition also has a deep current of philosophical friction associated with it, and I tend to write new songs by using the same hardened punk themes but expressing them in new ways. By doing so, I believe new standards can be achieved. By the same token this book is not the proposal of a new principle or theory; it’s more like a song, like an artist’s attempt to craft a worldview. Using the facts of evolutionary biology and geology as my palette, I see parallels in the way populations interact with one another today and in the past history of life on earth. I see consistent repetitions in these interactions throughout the episodes of history, and I think they are trying to tell us something. I want to elaborate some of my findings, knowing all the while that, like a punk songster, some of what I have to say is distasteful to many.
Even though I’m not a household name like a lot of rock stars, I feel privileged that I regularly travel the world to perform. I’ve used this privilege to visit museums, head out on excursions away from some of the exotic cities we play, and come home, reinvigorated by my travels, to lecture at universities on topics in natural history such as geology, biology, and anthropology.
These great pillars of knowledge used to be more closely allied than they are today. The first geologists were essentially creators of Earth’s chronology, using fossils and rock layers to mark the events leading up to the present day. Fossils had to be compared with skeletons and remains from living species. So every geologist had to know something about biology. Likewise every anthropologist had to understand biology—for humankind, the subject of the discipline, is a mammal of the Order Primates—as well as geology. The chronology of our species is ultimately calibrated by dating the layered sedimentary deposits associated with human activities. Human history, a story that is at least two million years old, is therefore superposed on a geological foundation.
Of course not all anthropologists today pay much attention to geology—for modern culture came about during just the most recent tiny fraction of time in earth history. In fact today scientists tend to specialize and become hyperfocused on one unique topic within their field. It’s generally not encouraged at universities to mix disciplines, but rather to pick only one, and in it, find some species or patch of Earth and study it completely. Become an expert on something small—that way you cannot be assailed as a phony or a “soft science” advocate (a somewhat pejorative term usually reserved for those of us who try to meld disciplines at a coarser scale of analysis). The tunnel-vision approach to science has never appealed to me. I feel that too much focus might lead me down a long, lonely path of overspecialization, with no significance to a broader audience. Instead I’m motivated to arrive at a satisfying plateau of interdisciplinary conduct that blends, rather than excludes, other influences in my work. Topics from other fields, like influences from other genres in songwriting, have been the mainstays of my creative life.
Therefore, in science I took the “long way home.” I got an undergraduate degree in anthropology, a master’s in geology, and a Ph.D. in zoology, as I continued to write songs with my band and tour whenever the opportunity came along. It took me about fifteen years to accomplish this education; others have done it much faster.
Even though I still learn new things every day, I’ve started to be more confident in melding my classical training in zoology and paleontology with observations on the current state of our industrialized species. In a sense I’ve taken an anthropological approach, and I’ve come to recognize that the great disparities in quality of life today seem to be entrenched, not something that can easily be overcome simply by a person’s hard work or dedication to a particular ideology. Rather it seems that the human population is participating in an elaborate ballet arranged by an unseen choreographer. Historical and economic circumstances have relentlessly thrust groups of people into contact with one another, bringing about violence and warfare. These violent episodes have repeatedly resulted in assimilations of the human species. Think of the conquest of Mexico or, as will be illustrated in a later chapter, the European settlement of New York. In both cases economic (or ecological) necessity drove populations together, violence ensued, assimilation resulted.
Such mainstays of the human drama are paralleled in populations of wild species. The easily observed historical pattern of conflict, followed by assimilation of populations brought into contact by the same environmental parameters, depicts what I call population wars. The first half of the book illustrates some of these. For instance, the rapidly expanding compendium of knowledge about other species that live inside us and all around us provides an eye-opening set of reasons to be concerned about our own population. As I lay out these examples, the perspective I’d like you to take is that of a naturalist, observing the empirical evidence of the wild, while still recognizing that we are a part of (not apart from) this elaborate biological pageant.
The second half of the book will require the reader to wear a different hat—that of the philosopher. The ultimate goal is to facilitate a shift in focus, away from the individual human being as an inheritor of free will from on high and toward an appreciation of the constraints placed on her by the circumstances of the group(s) to which she belongs. The result should be a recognition that we are all survivors of the population wars of the past, and we can use this knowledge to justify a peaceful stewardship of the planet.
Our journey will begin in the earliest days of life on our planet. Through tales of mass extinctions, developing immune systems, ancient human wars, the American industrial heartland, and our ever-degrading modern environment, the common thread of population wars will emerge. Our cast of characters ranges from simple cells in the primordial soup to plague-infected fleas in the Dark Ages, to American Indians in the Revolutionary War (1775–83) and modern-day, out-of-work skilled laborers in former manufacturing communities. We’ll look at species that are in the process of becoming endangered, and others, like the horseshoe crab, that have remained relatively unchanged for hundreds of millions of years. All these groups have commonalities that weave the narrative fabric of this book: They are composed of distinct populations, they have all assimilated to varying degrees, and they all have attributes of coexistence in the modern world.
I feel it a great privilege to teach at Cornell University. Like most colleges, it’s a hotbed of liberal beliefs and hippy ethics. Many years ago I started to see the bumper sticker around campus that spells out COEXIST—with each letter produced from an icon of the world’s great religions. It’s easy to dismiss this statement as too simplistic, yet the philosophy of coexistence has stuck with me. I think it is time to subject it to an intellectual discussion. We are all individuals and (as we will see) composed of numerous populations of other individuals as well, but we are also part of a population. The owners of that bumper sticker probably identify with one of the various religions depicted by the symbols, but their basic point in advertising the word is, Can’t we as individuals put aside our differences and just get along without violence? It’s a wonderful sentiment, and as an individual I agree with them. But as part of a population, we are constrained by various historical contingencies. The humanitarian goal of the twenty-first century as I see it is to learn those constraints, face them squarely, eliminate them, and agree on a global course of action for our species. The goal of this book, however, is simply to make you aware of some of those constraints, understand how they operate, acknowledge their importance, and consider the validity of this approach. What you choose to do next is up to you.
Obviously, I love natural history and specifically the study of evolution. But I also have children, and I take my role as a parent very seriously. Part of that role is figuring out the best way to introduce them to our culture. This is a process of assimilation, and each child is like a population. I have to acknowledge that my kids will experience pain and trauma before they attain stability and self-sufficiency. Although as parents we try our best to ameliorate suffering, growing up is always painful. In a sense the painful changes kids experience throughout life can be slightly mollified by parental stewardship—coaching, training, leading by example. Most important to this effort, however, is the realization that a future awaits these innocent loved ones. By presiding over the development of their bodies and minds we prepare them for that future. We feed them food and ideas, in each case creating an environment to meet the challenges they will face. Whether we admit it or not, we are acting as ecological stewards for the most precious ecosystem of all—the minds and bodies of our offspring, composed of developing cells and populations of symbiotic microbes.
By extension of my instinctive drive as a parent to foster intelligence and health in my children, I propose that there is a fundamental reason to advocate for environmental stewardship for the planet at large. The kids will inherit the Earth we leave to them. Now that every inch of the globe has been explored (and I’ve had the great privilege of exploring so much of it), I’m convinced that humans have the technology and knowledge to leave it in better shape than we found it at the time of our birth. There are many steps to this ambition. Mapping, for instance, is a fundamental one that has already gotten off to a fantastic start—just spend a half hour on Google Earth. Searching for the basis of coexistence, however—the theme of this book—is another key factor in the successful stewardship of the future. After all, human coexistence ultimately depends on our coexistence with other species.