Human populations can hardly be characterized as currently living in any kind of equilibrium. Rodney King, the reluctant face of the 1994 Los Angeles riots, famously asked, “Can’t we all just get along?” The answer to his question is, “Not really.” Without a unifying principle or ethic, the human race will continue to be fractured into subpopulations that have only their own self-interests to guide them. So far no human group has developed and passed along the cultural narrative that is necessary for peaceful coexistence.
Unfortunately most groups of humans lack empathy for “others,” and without it there is no common goal. The idea of working together for a sustainable future as an ethical imperative is a new concept; it may just take a long time for humans to figure out how to avoid conflict and cooperate instead.
Once we accept the long history of population wars we have to conclude that they are inevitable, and this means that we cannot get along unconsciously. Getting along—like most meaningful human endeavors—takes effort. It will require education, governmental policy, heightened awareness, and in some cases enforcement to do so. Look at something as simple as plastic shopping bags; we all know they are “bad” for the environment, but for the most part we stop using them only once a local ordinance bans them from our shops. These kinds of seemingly petty regulations—no matter how much they may gall our libertarian friends—are necessary. They are a small part of a bigger shift that will tweak the norms of behavior to benefit the environment and enact a grand compromise for the good of our species.
So how do we “all get along” as a species? It can’t be as hard as some would make it seem; the natural world is full of species that are able to do it despite their seemingly incompatible needs. The answer is for mankind to become a race of enlightened citizens among the community of other species with whom we coexist. The first step in our collective raising of consciousness is to look at how coexistence has been achieved in the natural world, and in the unconscious unfolding of human history. Throughout history we have been involved in grand compromises without even being aware of them.
On a recent drive along the country roads near my property in upstate New York, I passed a mangled piece of roadkill. Since I live out in the countryside I usually spot one or two deer carcasses a day. These deaths are unfortunate but inevitable. The deer like to graze along the grassy shoulders of the highway; as they eat they get spooked by traffic and dart into the road, where they are hit by oncoming vehicles. Their remains litter the sides of the road, and drivers rarely—if ever—stop to acknowledge the damage and death. Sometimes the animals have the last laugh; the impact of a deer on a small car can be dangerous to the driver as well. Everyone in my town knows the story of the farmer who struck a deer dead-on—elevating the animal just enough to lift it over the hood of the car and sending it through the windshield headfirst—and was impaled in the neck with the sharpest antler point. But the damage didn’t stop there. The momentum of the deer carried it well over the front seat of the car through the backseat, and smashed through the rear windshield, meanwhile having completely decapitated the driver! When rescuers reached the crash, the deer could not be found. They assumed the deer was well enough to hobble away. If it eventually died from its wounds, it did as much damage on its way out of this world as it received in the brutal collision.
When I see a dead deer, I don’t feel a deep sense of sadness for the poor helpless animal. Usually my sympathy is equally balanced by the possibility of the driver having been decapitated. In other words, the tragedy of the dead animal doesn’t overwhelm my emotions. I see the roadkill as evidence of two populations, human and deer, each going about its own selfish ways. Sometimes these populations interact; sometimes the results are violent. Even when individuals are killed in the process, both populations adjust to the interaction. Drivers are more cautious and aware of the deer, and the deer population has one less individual to breed and pass along the dangerous behavior of grazing near highways. It’s simply the winnowing effect of natural selection.
I also realize that if the deer population grew out of control, there would be many more accidents. Eventually the humans would have to adjust, by building fences or erecting deer-repellent barriers on the shoulders of the roads. Conversely, if the human population grew, as in large cities, the deer population would shrink drastically. Habitat would change from grazing lands to cemented pavement, and the killing rate would increase from the expansion of cars and trucks on the road. Eventually the amount of roadkill would reduce to almost zero, not due to safer behavior on either side but due to few deer. It’s a rarity to see any dead deer on the roads of Los Angeles because the deer population is now sparser than it was before the urban sprawl of the twentieth century. Hardly any drivers in LA have to be mindful of deer as a potential hazard.
The point I am making is that seeing a dead deer on the side of the road isn’t so much of an individual tragedy to me as it is an indication about the realities of where I live. I use this information to make sense of my environment instead of getting overwhelmed by emotion of this or that incident. It’s emotional detachment in favor of intellectual processing and planning.
I apply this detached attitude to other aspects of my day-to-day experience. I went to college in Los Angeles in the eighties; every day I would pass a few homeless people living on the streets between my off-campus apartment and UCLA. Today, remarkably, homelessness has spread outside our major cities. Now when I tour or travel, I see homeless youngsters begging for cash, and young mothers holding their hands out for change in the suburbs and small towns across the country. It’s no longer easy to avoid the realities of a growing homeless population in our land just by moving away from the urban centers.
Still, I try not to get wrapped up in the tragedy of each individual; instead I look at it as a consequence of something affecting our population, and wonder why homelessness became their best—or only—option. The reality is that the absolute number of unemployed people has gone up in our country as the population has increased drastically over my lifetime, and the number of social services has gone down in the past forty years. The cultural environment in the United States has shifted, it seems, and hardened into one that promotes a less compassionate view of our unfortunate citizens. Some assume that homeless people are homeless because they lack the moral backbone or ambition that propels the rest of us forward. Some successful people invoke a kind of pernicious Darwinian misapprehension to justify their negative view of others: If Darwin proved “survival of the fittest,” then the less successful people must be less fit and therefore undeserving of successes. The reality of homelessness and indigent citizens is more complicated than a shorthand phrase for evolution, however. Poverty, mental illness, lack of human services, and family or personal tragedies all play a role, and they have more to do with historical circumstances than any personal strengths or failings of the individual members of the homeless population. The political agendas of both dominant parties, particularly in the last decade, have been hostile to government agencies that could help the population of homeless people. Sympathy is out of fashion, as evidenced by cable news, where you are more likely to hear that “we are all on our own” and that government assistance—whether it’s funding for homeless shelters, food banks, or mental health facilities—should be ended. Luckily the political environment is changeable, and this can lead to cultural change.
In simple terms our society can be divided into the haves and have-nots. I’m fortunate to be a have, but I still find it easy to sympathize with the have-nots. I know that my future is tied up with theirs, and that making things better for our society as a whole is more important than simply making it better for my immediate family and me.20 Unfortunately, another view that is common among many of my fellow haves, is a senseless antipathy and narrow-minded harshness toward the less fortunate: These homeless bums are just looking for free handouts, taking advantage of charity, and not carrying their own weight. I had to work hard to get to where I am; no one gave me handouts. This shallow and inaccurate mantra reflects a portion of our society that has ancient roots. It is, like so many unexamined beliefs, a narrative of self-sufficiency that has very little basis in reality. Like many successful Americans, I had an average middle-class upbringing that included an adequate school, a reasonably stable family, and good health. Who knows what would have happened if I’d gone to a shitty school, had unreliable parents, or had a chronic illness. Perhaps I would have become one of the have-nots after all.
The reality is that most of us lucky enough to be haves have enjoyed subtle advantages throughout our lives. If we accept this, and remain aware of the differences between our social situations and those of the less fortunate (and how those helped determine our current status), we can begin to develop a much-needed sense of empathy toward the larger world.21
The deer that graze near the highways around my house have no idea that their lives are in danger from the trucks and cars speeding alongside them. Had they been born with an avoidance behavior that kept them away from cars, they could take action to prevent themselves from coming to a potentially violent end. Similarly, without any understanding of the multifarious causes that lead to homelessness, how can a population of privileged but unaware humans develop any kind of public policy or social action to make the situation better?
There’s a bigger point here: If we want to avoid extinction, and commit ourselves to long-term sustainability, we will need a greater sense of awareness of what’s happening to our environment, on both a local and global scale. We need to learn to care about issues that don’t directly affect us as individuals; in other words we will need to worry more about the common good than our own interests. The most obvious way to do this is to reject the superficial and selfish mantras about “makers” and “takers,” and instead focus on sharing fact-based knowledge. As social scientists collect more information about the world, for instance, it should become clear that assistance for the less fortunate benefits us all.
For most of the history of Western civilization, life was explained in terms of purpose. Aristotle, the great “first philosopher,” began a tradition of teleology that is still the foundation of how we view the world. Teleology is the intellectual practice of explaining things with respect only to their purpose. A teleological explanation for the variety of trees in a forest might go something like this: The purpose of the forest is to provide nesting places for spotted owls and other species of birds. Teleology puts the emphasis on why something exists. In many religions God becomes the answer to most of the “why” questions. Why do I exist? Because God created me for a specific purpose.
Evolution, however, is explicitly nonteleological. There is no ultimate purpose to why you exist, or to all those trees in the forest. The variety was produced over a very long time by “natural laws,” including natural selection, heredity, and genetic recombination (among others). Humans, like tree species, are the product of millions of years of evolution and natural selection, and we have extinct ancestors to prove it. With no ultimate-purpose, “how” we came to be becomes a more interesting and relevant question than “why” we came to be.
Part of the problem with teleology is that it biases the average citizen’s thinking about social issues. Perhaps you believe that the purpose of a free society is to allow individuals to accumulate as much material wealth as they want, regardless of the cost to the biosphere. If you meet someone who doesn’t believe this, then they are in conflict with the purpose of a free society, and they may be ignored, discredited, or worse.
If our purpose is a foregone conclusion and there is an overriding belief that the world exists solely to serve human needs, then we are justified in scorning those who seem to be going against purposeful order. If society is ordered simply to satisfy some overarching purpose then it becomes logical to blame and punish those who challenge the order. But what if our perception of the purpose is wrong? Isn’t it just as logical to believe that society, like virtually all populations, is a complex of interacting individuals focused on short-term needs? In such a world there is no single overarching purpose that applies to everyone.
Aristotle believed that the only explanation for animals and plants was in relation to their purpose. “Nature does nothing in vain” is a common quote from his philosophy, in which nature was all-purposeful. All things functioned with respect to its purpose, in deference to a “final cause.” But today we know that nature does all kinds of things in vain. Think of mutations, for example. The natural properties of populations reveal no ultimate purpose, but rather they could easily be seen as mere reservoirs of biological and behavioral diversity. We have to conclude, therefore, that Aristotle was wrong in one respect at least. His teleological philosophy cannot easily be applied to humans. If there is a purpose to be had for the human race, it is one that will have to be agreed upon, such as the goal of the longevity and sustainability of our species. This agreement of working together toward an arbitrary goal seems healthy and good for us, but it is entirely different from the “final cause” that Aristotle believed was an inherent property in the universe, responsible for the creation of all things.
Under Aristotle’s teleological worldview, all you had to do to figure out why something existed was to figure out its purpose. Once you knew the purpose of something, you then knew the reason for its existence. This idea is a powerful one; throughout Western history things were explained in relation to their purpose. This became the norm in the universities of the Middle Ages, and it was readily adopted by Christian theology as well.
As the Christian population expanded, so did the intellectual idea of ultimate purpose. Most of the activity that took place in universities until the advent of science in the sixteenth and seventeenth centuries was centered on disputation: reconciling discoveries with what was written in the Bible. God’s plan, as revealed by his word in scripture, became the go-to explanation for the purpose and existence of all things. Hence Aristotle’s “final cause” was repurposed in the universities of this era and understood to be “God’s will.” Why do species exist in their current forms and seem so perfectly adapted to their habitats? An early naturalist from this period of time would say, Because they are conforming to God’s plan.
As far as can be determined from a study of nature today, however, there is no overarching design or plan. Modern scientists are more interested in looking at process rather than purpose. We look at a population and ask how it came to be, instead of the teleological explanation of why it exists.
As soon as you adopt a scientific or naturalistic worldview you realize that populations come together because of properties that are fundamental to their biology. Certain needs must be fulfilled in order for an individual to remain viable. If those needs are not met, existence is impossible. All populations are therefore the products of only “chance and necessity.”22 There is no overarching purpose to their function or existence. This is an explicitly nonteleological way of looking at the world. The contact between any two populations is based on mathematically determined probabilities that depend on highly complex variables, such as the population growth rate, increase in geographic ranges, and resource abundance and efficiency of its utilization, for each population. Once you take into consideration the plethora of groups coexisting simultaneously you realize that these interactions are too complicated to be explained as the result of a simple purposive design. In other words, giving population interactions teleological explanations is overly simplistic and not in accordance with what we see in nature. Instead it is more important to figure out how the two populations came together, and recognize how their histories impact their present state of interaction, with a mind to managing their future.
In general I think it is more exciting to ask how something happened rather than worry about why it happened. Unfortunately most people still think and act teleologically. One of the most popular books in recent years is Rick Warren’s The Purpose Driven Life, which suggests that everyone is put on Earth by God to fulfill his given purpose. It has sold well over 30 million copies! I find this disappointing but understandable; no doubt it is reassuring to believe that “everything happens for a reason.” But the truth is that there is no ultimate reason, and the greatest challenge to overcoming teleology is the admission that our lives have no predetermined purpose, and that, furthermore, we have far less control over the direction of our individual lives than we think. The religious deal with this lack of control by telling themselves that God “has their back.” For them it’s soothing to believe that God has a purpose for all of us even if we don’t know what it is. Believing that God’s plan is a secret known only to him might seem comforting to some, but to others—myself included—it brings no sense of peace. I’m a skeptic. I need to see some proof that someone gives a shit about me. I feel that it is far more realistic to assume that no deity (or any corporation for that matter) cares a hoot about me as an individual. I’m content with the love of my family and friends.
I can see how a belief in God and a defined plan makes people feel great. Unfortunately the belief in this “ultimate purpose,” and the promise of a paradisiacal afterlife in a supernatural world of endless bounty, stands in stark contrast to the naturalist worldview that sees our biosphere as fragile and finite. The only real afterlife, to a naturalist, is the paradise around us—one that if we are lucky we will be able to leave to our children. There is no real agreement on what is best for the long-term success of our species, and in part this is due to the seductive and reassuring teleological belief system that is at the core of most religions. Each one presents a different path to salvation and a different purpose for the use of Earth for their benefit alone. Many people seem to believe that God’s ultimate purpose includes extracting, harvesting, and generally obliterating any life forms, even other humans, that are foolish enough to come between them and potential profits.
The teleological view is closely mated with the persistent belief in free will (discussed in chapter 9). When belief in an ultimate purpose is backed up by a belief that all people are free to pursue it, two very toxic fallouts result: blame and punishment. Why would anyone use their free will to disrupt God’s ultimate purpose? The belief is that no one of sound mind should escape being punished if they knowingly do something bad. Leaving aside the data that shows punishment doesn’t work,23 this kind of reasoning is the justification for viewing Rodney King as a perpetrator in the LA riots. Sure, King might not have been behaving like a model citizen when he resisted arrest, but there were profound historical circumstances at play that are far more influential than his supposed free will. Remember that he was driving drunk and resisted arrest, which led to his beating by cops who were probably provoked by his belligerence. The more complex and perhaps relevant “how” questions, however, didn’t get asked in that moment. A video captured a portion of the beating, the national news programs played only the most sensational part, showing the swinging batons (not the part where King was belligerent), and the public reacted to the viciousness. When the cops were acquitted of wrongdoing, Los Angeles citizens, mostly from the African-American community, blew off their anger in a fit of violence, vandalism, and terror. The rioters blamed the cops, the cops blamed Rodney King; both groups felt that the other was wrong, the anger and frustration was exacerbated, and the situation quickly devolved into chaos. What should have been at the forefront of everyone’s mind was the environment of hostility between the LAPD and the African-American community, which had existed long before the beating took place.24
Violence and chaos might be curtailed, sympathy and empathy might become more prevalent, if interacting populations encouraged a wider understanding of one another’s history. Context makes it difficult to interpret history simply in terms of “good guys vs. bad guys.” But it takes time, sometimes generations or longer, for the context to be understood and spread as general knowledge in a population. Such cultural assimilation, however, might be fostered by an outright rejection of teleology.
Nonhuman species interact only within the context of ecology. Their geographic ranges—the front lines of their population wars—are determined by niches comprised of multiple dimensions (mathematical abstractions referred to as “n-dimensional niche spaces”—more on this later). Most species have no way to avoid the inevitability of conflict if their population is growing out of control. Soon their resources will become scarce and their numbers will dwindle. Once you accept that species in the biosphere have no ultimate purpose—only a proximate purpose under the constraints of environmental selection—you can start to appreciate what brought them together. Scientists often ascribe purpose when they speak of adaptations “for” this or that particular function (for example, flying or swimming). This can be easily misconstrued and equated with theology—that is, how theologians speak of God’s plan in the creation myth of the human species. This way of thinking is merely meant to be descriptive, and doesn’t square with a starker interpretation of biological data. When taken at face value there is no ultimate purpose for the existence of a species. That is to say there is no long-term, goal-oriented, preferred endpoint, or an intelligently designed trajectory, to any evolutionary lineage or population.
Species exist because of environmental parameters that “allowed” their evolution. Each individual is simply meeting the conditions of existence in order to survive and reproduce, both of which can be considered proximate purposes (those that serve the immediate needs of an organism—nourishment, nesting sites, reproduction, and so on). No biological evidence exists that shows an ultimate purpose to the evolutionary process. In fact evolutionary lineages have repeatedly shown historical trajectories that change direction, speed up, slow down, and sometimes inexplicably terminate, all in response to their ever-changing environment. Studying the fossil record, where data like these are abundant, gives ample reasons to view life as ultimately purposeless.
While this might seem disheartening to some, for me this knowledge gives life more levity. In a simple, everyday sort of way, I can reason that there’s no ultimate purpose to a mosquito, so it’s futile to hate them for ruining your camping trip. Instead, why not try to understand how mosquitoes function in nature and how they interact with us. It’s more productive to think about their general behavior, distribution, and possible breeding sites than it is to complain about the bites. This knowledge allows us to tweak certain aspects of their biology in an effort to actively manage their population and possibly reduce the spread of malaria, the disease for which they are known to be the main vectors, and more prosaically to avoid them while camping. .
Naturalists and environmental scientists look at environmental factors and species’ functional ecology first; they don’t worry about why species behave the way they do. Instead they simply deduce how things came to be. We need to adopt the same approach when dealing with one another. First and foremost we should come to terms with the fact that we are all of the same species, regardless of nationality or belief system. We form a very large, global population. If we can resist the urge to blame and punish one another, we will improve the odds of our species’ long-term survival, and reduce violence in the short run. But to reach this level of enlightenment, we need first to reject teleology, as explained above, and then come to accept some of the basic biological facts about populations.
Most people think of “the population” as implicitly a human construct. For instance, “The population is growing in Jacksonville, Florida” because people are moving there at a rapid rate, making conscious personal choices to relocate: more jobs, better schools, nicer climate, and similar reasons. But biologists use a more basic definition of populations: A population is a collection of organisms linked unconsciously to one another due to some property of their biology—most important, reproduction. The most obvious thing that links all members of a population is heredity—they all carry the same DNA, the same genes. In fact, populations are often defined precisely by the genes that their members all carry.
For instance, the species Rana pipiens—the cute little frog that inspired Kermit from Sesame Street—is distributed throughout North America, but is divided into numerous discrete populations that function separately. This is common of many widely distributed species: They can be divided up into “races,” sometimes called “demes”—groups that differ only superficially from one another. Although all individuals of the species carry the same genome, their genes are variable across the geographic range. In the case of frogs, we can assume that their breeding circle in Oregon is completely isolated from individuals in Florida because it’s impossible for a frog to traverse that much distance in its lifetime. Sometimes this is referred to as a localized population.
Localized populations are effectively separated from the “gene pool” of the entire species. A gene pool is a collection of all the gene varieties that comprise a species. Theoretically speaking, all the genes in a gene pool make up the evolutionary raw materials from which natural selection can function. In reality, however, evolution occurs in localized populations, and these are disconnected from other such members of the species. In this sense populations grow and adapt based on their own properties, sometimes on a separate evolutionary trajectory from the other members of the species, because there is effectively no connection to the rest of the gene pool. But again theoretically speaking, if they are the same species they could breed with one another if collected and taken back to the lab.
The various demes that occur throughout a species’ range each have slightly different genes. Evolution is defined as a change in the gene frequency from one generation to the next, and this underscores the basic point that most evolutionary biologists like to emphasize: Genetic change—and thus evolution—occurs in isolated populations of a species, and only by adding up all these isolates, and tracking the changes in their gene frequencies from one generation to the next, can you tally the evolution of the species as a whole. Sometimes the isolated populations change in divergent directions, and over time the split creates two distinct new descendant populations. These groups eventually become reproductively isolated, which means that they can no longer interbreed with one another, only among themselves. This is the typical example of one ancestral species splitting into two daughter species.
Some genetic changes get weeded out over many generations because they impair the reproductive potential of the individuals that carry them. Other genetic variations, however, increase the likelihood of successful reproduction, and over time, and through many new descendant generations, they spread to more and more individuals until the frequency of those favorable genes in the population reaches a maximum.
Obviously the frogs are unaware of this process. The individual Rana pipiens have no ability to figure out if they are carrying genes that increase or decrease their potential to reproduce successfully. They’re simply preoccupied with being frogs. Just as no human instinctively knows if he or she is carrying genes that aid in successful breeding. One thing is certain: It takes a very long time, perhaps thousands of generations, to determine which genetic varieties are on their way out of a population and which are on the way to becoming fixed in a population. Evolution is hard to see in most animals and plants because its time frame is rarely experienced in a single human life. We have no direct experience with the phenomena of long-term evolutionary change. We can only infer its causes, as we witness small slivers of time and small fractions of populations in a continuous process that spans millennia.
Every year I lecture to undergraduates at Cornell University. The class is open to students from every walk of life, which can make teaching evolution very challenging. Most of our students are “nonmajors” who have only a basic grasp of biology or science in general. Every year I get a handful of students who are self-proclaimed intelligent-design creationists. This usually has no bearing on their performance in the class, although they get a bit frustrated when it comes to the lectures and readings about human evolution.
I ask the same thing of all students: Learn the material and think carefully about your reasoning when answering questions on the exam. I’m not trying to convert them. I just hope that they take some time to think about the ways in which their beliefs might be incompatible with science. I never give someone a lower grade because of his belief system. If he rejects evolution as a worldview, he can still pass the course because students are asked only to evaluate the evidence and write about the “organizing principles” or theories that are supported by the empirical facts.
It is a basic fact of science that evolution happens. The simplest definition of evolution is “descent with modification.” But that phrase has a profound meaning. Superficially it just looks like “change through time”; and that would not be a bad first impression of evolution. However, the word “descent” means that evolution is dependent on heredity—relationships of parents, offspring, and the long lines of familial connections that stretch through the generations. This long, slow progression of change through time puts the focus on the group as opposed to the individual.
Think about the evolution of the horse, for example. Its journey has been captured in the fossil record. We can trace the horse back roughly 55 million years, and horses show a hereditary link with ancestors that stretch farther back into deep evolutionary time. The oldest horse, Hyracotherium, was the size of a small fox. Horses alive today (Equus) are more than ten times taller. Height isn’t the only anatomical characteristic that has changed. Its teeth are longer and show a more intricate grinding surface than their ancient ancestors’. Modern horses stand and run on one enlarged middle toe on their hind limb and a single middle “finger” on their forelimb. The other toes and fingers are absent, except for vestiges of ancestral structures. We can see where those vestiges originated by studying its ancestor Hyracotherium. Hyracotherium had four digits on its forelimb, and three on the hind limb that touched the ground and supported the animal’s weight. The key to understanding evolution is understanding how these changes occurred over tens of millions of years; how, in a single lineage of descent, a perfectly formed foot with four toes could change over millions of years into one with only a single digit.
Charles Darwin wrote about this philosophical puzzle from 1838 until his death in 1882. He didn’t have the fossil record of horses at his disposal, or any understanding of the hereditary material (DNA was discovered in the twentieth century), or any knowledge of molecular biology. However, his interpretation of nature was so astute that he crafted the modern explanation of how populations diverge from one another and from their ancestors. His keen observations focused on two main aspects of natural history. The first was the recognition that offspring resemble their parents, and the second was that all members of a population show variations in observable traits. To Darwin these two basic facts went hand in hand, and he used these basic observations to infer that all organisms are linked by the same principle of heritable variation. That is to say, he realized that traits are passed along more frequently from parent to offspring, but are imperfect copies of one another. The more favorable traits, those that aid in reproduction and survival, get passed along and proliferate among descendants. The less favorable varieties result in fewer offspring, and lower incidence of the traits in future generations. This process provided Darwin with a deeply significant insight: All organisms are connected by descent, and thus we should be able to trace back in time all organisms to a single original ancestor.
Today the modern theory of Darwinian evolution has been substantiated on so many levels that most educated people accept it as fact. We know that the heritable material is DNA, a large molecule composed of discrete regions known as genes. DNA is found in the nucleus of every cell of your body, and most important it is found in the cells that are stored inside your sex organs. When you reproduce, your offspring inherit a copy of nuclear material from Dad’s genes and Mom’s genes. The reason offspring don’t look exactly like their parents, however, is that they are a mix of materials from both of the parents’ sex cells. These are called the “germ” cells. They are found in the gonads—testes in the male, ovaries in the female. They are distinguished from the “somatic,” or body, cells. Germ cells participate in heredity, while somatic cells do not. You can change a lot about your body cells throughout life—think about calluses or big muscles—but you cannot change your germ cells. A single egg cell and a single sperm unite at fertilization. These two individual cells carry all the genetic variations necessary to ensure that the offspring will not be an exact clone of either parent.
Variation in the genes assures that the process of sex will always produce offspring that are slightly different from their parents. Another commonly repeated phrase in science is “Mutation is the engine of evolution.” Offspring differ from their parents because of changes in their genetic material. Some of those offspring might vary in size, or have slightly different teeth, or some might have more drastic changes, such as the number of fingers or toes.
The parent-offspring hereditary mechanism (which includes genetic crossing-over—or sharing of slightly different genes on chromosomes before they get sorted into sperm or eggs, and low-frequency favorable mutations) ensures variation within the family. It does not ensure, however, that a descendant population will differ significantly from the ancestral population. For that you need some sort of selecting mechanism that will weed out certain varieties of offspring and prevent them from reproducing. This mechanism is called natural selection. Evolution occurs when certain offspring varieties are favored over others across an entire population. We say that those favorable variants have been naturally selected, and since the unfavored fail to pass on their genes, the population that results after another round of breeding will show genetic variation that is different from the previous generation. These naturally selected, slight variations in descendants are the measurable effects of the evolutionary process.
In nature things are much more complicated than this rough sketch of natural selection. The reason that natural selection is so hard to measure in nature is that it depends on two equally important factors that are constantly in flux: (1) Heredity—sperm cells are continuously produced throughout life, and each one of them has pluripotential genetic material that is active during millions of cell divisions after reproduction. At each step of embryonic development there is the potential for mutation in one or many of the offspring’s cells. Eggs are produced in great quantity, each one of which carries its own set of gene variants. (2) Environment—at every moment the environment changes, with each gust of the wind, each encounter with another individual, each flash of sunshine. It is the interaction of these two constantly changing factors that determines the reproductive success of an individual. The cumulative outcome across the entire population of offspring is how we measure natural selection.
This simplification is useful because it demonstrates how natural selection is a two-step process. Individuals can get only so far. Without the appropriate environment as a selecting mechanism, it doesn’t matter how fast you can run or how quickly you can solve a problem. Possession of individual traits does not guarantee their long-term success. Reproduction and functional utility are both subject to circumstance. If conditions that promoted success in the past change significantly, a trait that was beneficial in the past may become a burden. This justifies a strong emphasis on understanding the environment’s role in shaping the population.
The degree to which an offspring population can vary from its parental stock is predicated on the stability of the environment. If the environment has undergone a drastic change beyond that to which the parent population was finely adapted, the more similar offspring—those resembling their parents—will be selected against. Some fraction of variants among the descendants might match the new environmental parameters well, in which case they will form a new population radically different from their parents. In this case (drastic environmental change in one generation) descendants would not resemble their parents. It is in this sense that we can say that the environment “allows” new varieties to form.
Sometimes the hereditary raw materials, DNA molecules, undergo a biochemical “mistake” called a mutation. These kinds of biochemical mistakes happen within the nucleus of the sex cells when the maternal and paternal genes combine to create a new life. These genetic mutations occur spontaneously and most often cause serious problems in the developing embryo. Although we can think of mutations as a “natural” spontaneous biochemical process, it has been well documented that human activities can increase the rate of mutation through “unnatural” means, such as proximity to radiation, smoking, unhealthy diets, pesticide ingestion, and soon. Even without these human sources, small mutation events occur constantly in the gonads at a theoretically determined rate. Often they go unnoticed because the sex cells fail to become successfully fertilized.
These mistakes are almost always detrimental, causing impairment or death to the individual. But occasionally mutations turn out to be useful in some way. Think of a mutation that caused more hair to grow around the face in a cold climate, for instance. This would be a detriment if the climate turned hot—you would want to shed heat, not retain it. But in a cold climate the extra insulation from a beard could give the individual an edge; he would live longer, reproduce more, and eventually natural selection would bring about a population of furry-faced men. Over the long run of the evolutionary time-scale, a single hereditary mistake in one individual, if beneficial, can affect an entire lineage of organisms because it confers a reproductive advantage to all offspring who carry it.
Horses evolved over 55 million years because of very slight mutations. A male Hyracotherium may have passed along a sex cell that had a mutation that caused a slight reduction in all but the middle toe. Somehow this trait benefited his offspring—perhaps allowing them to have a longer, more unobstructed gait. This next generation of horses, being better at running, was able to avoid predators, attract more mates, and breed more successfully than those with a full complement of long toes. The mutation was passed along to every horse descended from this hypothetical ancestral population. Their descendants increased in number until every horse carried that mutated gene. The mutation may have started off in a single individual, but it soon became a fixture in the descendant populations because it was passed along so successfully.
Evolutionary science is essentially the study of populations through time. When we look at our world through an evolutionary lens, we can tease apart hereditary and environmental phenomena and start to figure out the processes that have shaped the human population and those of other species as well. Individuals are not strictly in control of their own destiny, because they are at the mercy of their heredity and their environment. The environment of an organism consists of two parts: (1) Biotic interactions—encounters between organisms; and (2) abiotic factors—those that depend on the climate, geography, altitude, or other physical conditions such as temperature, sunlight, salinity of water, or soil chemistry. The environment plays numerous complicated roles throughout the life of an organism and throughout the history of a population. In humans, culture has a profound influence on biotic interactions. Heredity is the transmission of traits from parent to offspring. The laws of heredity (worked out originally by the Austrian biologist Gregor Mendel) were determined in the absence of environmental influence, under controlled experimental conditions.
In nature the interaction of environment with heredity determines which genes are expressed and in what ratio. The environment also plays a key role in determining probabilities of successful mating. A particular gene might have a very low probability of getting passed on under certain environmental conditions, but if the environment changes the probability of that same gene being expressed might increase. In this way the environment works in tandem with the hereditary process. The flip side of this fact is that individual actions do not shape a population unless the environment allows them to flourish. This is such an important point that it cannot be overstated. If the environment is not receptive to a mutation, it will be quickly eliminated from the population. As a parallel phenomenon, in culture, ideas only spread if they are received by others and then repeated. The cultural environment, therefore, “allows” ideas to spread.
Those of us who live in relative comfort in the Western world like to think that we are in control of our destinies. We watch what we eat, how we exercise, and how we deal with the world around us. Most people assume that evolution is no longer affecting human beings. “After all,” they say, “haven’t we effectively insulated ourselves from the harshness of natural selection through the buffer of urban living and modern technology?” But evolution is ongoing, and our environment continues to interact with mutations in our genes. Sickle-cell anemia, a genetic affliction that is present in people of African, Middle Eastern, and Mediterranean descent, is an example of this. Sickle-cell anemia causes severe blood problems in those who carry the genetic disease, yet it persists. Why hasn’t natural selection weeded it out of the human population entirely? It takes only a few generations to remove deadly mutations under natural circumstances. There must be some selective benefit to having the condition. Let’s examine this more closely because it tells us something about how natural selection brings about the coexistence of a perceived evil—a mutation—in our population.
Malaria is a good candidate for being the deadliest disease on the planet. It killed roughly seven hundred thousand people in 2010, and the World Health Organization estimates that one child a minute dies because of the disease in Africa. The prevalence of infection by malaria is closely matched with the prevalence of sickle-cell anemia, in tropical, wet climates where mosquitoes are most abundant. Mosquitoes transmit malaria when they bite, attacking almost all humans living in tropical climates, but especially those at their most helpless: infants.
A microscopic parasite, Plasmodium falciparum, is the agent of the disease, and it spends its life cycle in the blood of humans and mosquitoes. After a human is bitten by an infected mosquito, the parasite quickly finds refuge inside the human liver and eventually comes to reside within the circulating red blood cells. If you are carrying this organism around in your bloodstream, you are infected with malaria, and it causes a biochemical change to your red blood cells: They become sticky and clog the arteries that feed your vital organs.
Malaria is deadly. The parasite evolved to travel easily between mosquito and humans; once bitten the victim quickly grows sick, experiencing fever, internal organ dysfunction, and vomiting. Young children die quickly. Human babies, in the time before modern medicine, had no way to resist or combat the infection. It is here that mutation comes back into our discussion. Imagine a mutation that changes the susceptibility of blood cells to infection by the parasite. This is precisely the case in sickle-cell disease.
Individuals with this hereditary mutation are protected from the parasitic malarial infections. It should come as no surprise, then, that the sickle-cell gene is more common in human lineages that originated in tropical climates where malaria is most common.
The sickle-cell trait stems from human mutation on one portion of a single gene, and it’s relatively benign if it occurs on only one of the paired chromosomes in an offspring (that is to say if the child received the gene from only one parent). The offspring in this case are considered “carriers” of the sickle-cell trait. If, however, an offspring inherits two of these mutations, one from Mom and one from Dad, very serious problems arise.
Sickle-cell disease shows up as improperly formed red blood cells. These cells are responsible for carrying oxygen to all the tissues of the body, and in sickle-cell disease they become flattened and curved like a sickle. This makes them somewhat immune to the malarial parasite. But there is a downside. The malformation also causes obstruction of the blood vessels and problems with kidney function, lung function, spleen function, and a host of other serious problems. Carriers of the disease might live long enough to reproduce and live fairly normal lives with minor ailments coming from the malformed red blood cells. People who inherit two copies of the sickle-cell gene variant (one from each parent), however, will experience more severe cases of the condition and die earlier having had fewer—if any—children.
The population of vulnerable people in the tropics is thus stuck between two diseases, one caused by heredity (sickle-cell), and one caused by the environment (malaria). This balance between two terrible endpoints—sickle-cell anemia or malarial parasite—is called an evolutionary trade-off. An evolutionary trade-off is a compromise between two lethal alternatives. Both alternatives will lead to the individual’s death, but one (sickle-cell trait) has a built-in mechanism that will allow the individual to live long enough to reproduce.25
People who carry the sickle-cell gene variant might pass it on to their offspring. As long as the mutation allows the offspring to reach reproductive age, its presence will outstrip the negative effects of malaria by eliminating the “normal” red-blood-cell host preferred by the parasite. The long-term result will be growth of the human population in the presence of malaria because more offspring are living to reproductive age. Eventually this will result in a balanced frequency of the sickle-cell mutation in the population. Hence there is “just enough” of the mutation present in our species to match the proportion of those living in the presence of malaria.
The point of all this is to illustrate that everything in life is influenced by both hereditary and environmental factors. From such a perspective, we can perceive that much of life is neither completely within our control nor entirely our fault. And it serves to illustrate the difficulty of pinning the blame for a problem on a single culprit. For instance, if we destroyed all the carriers of the sickle-cell trait the environmental problem would still remain: mosquitoes carrying Plasmodium falciparum in the tropics. Infection rates would soar among those humans who live alongside malaria-causing mosquitoes because we would have removed from the population all those who carried natural resistance to malaria (those with the sickle-cell trait mutation).
Mutations arise spontaneously; the only way to prevent the spread of mutations is to limit reproduction. This idea comes worryingly close to eugenics, but—whether we want to admit it or not—a form of eugenics is happening all the time, all around us. For example, most parents are now offered the chance to screen their unborn child for Down syndrome and other prenatal maladies. Some parents, upon learning of a possible mutation early on in the life of the embryo, choose to terminate the pregnancy. We can prevent some unwanted mutations from spreading, but we can’t prevent mutation itself because it is a fundamental biochemical process that goes on during the development of every sperm and egg.
We can apply this outlook to our cultural environment. The political process, for instance, is rife with failed experiments and shortsighted schemes. I like to think that great ideas can come out of “mistakes” in the same way that genetic mutations are a kind of mistake in the nucleus of a cell. We have hundreds of seemingly useless thoughts every day, which arise out of nothing and seem to have no purpose. Most of these “mistakes” are forgotten before you’re even able to register them fully as ideas. However, some of these mutant thoughts are the spark of something brilliant and big.
Ideas live and die in the same way, and for the same reason, as genetic mutations. Valuable knowledge gets passed on to younger generations, friends, peers, and so on, who in turn pass them along to their kids. Human knowledge is as vulnerable to the forces of selection as are traits in nonhuman species. If the idea is useful (note: not the same thing as “good”) to the individual it will spread in the population, but a weak or unuseful idea won’t last long. Our thoughts are spontaneous, quick moving, and unceasing, so there’s no end to the potentially cockamamie mutational ideas we can come up with. My local newspaper is packed with evidence of this. Sometimes these ideas have surprising longevity. Other times they just fall flat.
I consider the idea that “corporations are people” to be a remarkable mutant idea. The idea of corporate personhood has a precedent; the U.S. Supreme court first invoked it when “corporate personhood” had to be established in lawsuits. Corporations are entitled to certain protections if they’re being sued, just as a person is entitled to certain protections if she is being sued. But the right-wing group Citizens United, which bills itself as political documentary filmmakers (or, more accurately, political attack ads that are falsely robed as documentary films) decided to try and push this idea further in the Supreme Court. This wasn’t supposed to happen. In 2002 a bipartisan law banned attack ads during the election season: The bill enjoyed bipartisan support in Congress. Most Americans from both major political parties agreed that this was a sensible thing to do.
Citizens United protested this law, lobbied heavily to change it, and the right-leaning Supreme Court reversed it in 2010. Their ruling invoked the U.S. Constitution’s First Amendment right to freedom of speech. Essentially they said that companies like Citizens United—which receive tens of millions of dollars in corporate donations—were entitled to freedom of speech just like any American citizen. Radio and television advertisements were now open forums for corporations to run anticandidate propaganda (previously illegal under the bipartisan law) just like a street corner where Joe Blow could shout his opinions without fear of legal repercussion. Somehow, Citizens United hoodwinked the Court into believing that corporations should be as unrestricted in their social reach as ordinary citizens; and the Supreme Court created an environment for this mutant idea to flourish. Now the idea that “corporations deserve free speech just like citizens do” is justified by official sanction.
The problem of course, and the grave error made by the Supreme Court (as pointed out in the dissenting opinions by minority judges), was that corporations were not the intended benefactors of the freedoms laid out by the Founding Fathers. The idea that the people should be allowed freedom to express their opinions was not intended for corporations:
“… corporations have no consciences, no beliefs, no feelings, no thoughts, no desires. Corporations help structure and facilitate the activities of human beings, to be sure, and their ‘personhood’ often serves as a useful legal fiction. But they are not themselves members of “We the People” by whom and for whom our Constitution was established.”26
Let’s look at this mutated idea from an evolutionary perspective. It originated as a mutation of a preexisting functional idea: American citizens deserve free speech, and therefore you can’t put someone in jail for expressing their opinion or for publicly presenting factual information. As this idea spread some people lost sight of what the First Amendment actually protects. Some people sincerely believe that corporations deserve First Amendment rights, likely because of the clever propaganda produced by Citizens United that misrepresented the ideas behind the Court case.
In reality, of course, a corporation wields far more power than any individual. So much power, in fact, that we often require limits on that power to prevent them from abusing it. Corporations don’t need the First Amendment; ordinary citizens do. But as the saying “Corporations are people” gets repeated, the environment becomes more receptive and the mutation spreads.
I’d suggest that this process is akin to the concept of horizontal gene transfer. Usually genes are passed from parent to offspring. In other words, organisms have to reproduce in order to spread their genetic material. Most bacteria, however, have the ability to share their genes with others of their own generation. This means that a bacterium’s gene for protein A can be given to another mature individual in its population, and that bacterium will then also begin to make protein A. Imagine if humans could do this. We could, for instance, simply change our eye color by receiving a gene from a particularly striking model whose eyes we adore through donation of her eye-color gene directly from her. Of course we know that we can’t acquire genes from those we adore. In order to share our genes we need to create a whole new person through the process of reproduction (hopefully with someone whose eyes we adore).
The process of sharing genes between individuals is considered “horizontal” because it doesn’t require reproduction “vertically” down lines of descent from one generation to the next. Ideas similarly can be considered as spreading horizontally. They can pass vertically, as in early education or perhaps family traditions, but since we are exposed to new ideas throughout life—and sometimes we incorporate those ideas in our adult behaviors—there is a strong analogy with horizontal transmission. Ideas can simply spread unchecked, from one person to the next, among the standing population. It is this property of ideas that led the English biologist Richard Dawkins to propose the concept of memes. Memes are like genes: They contain information, and they self-replicate. But in order to do so they need human brains and culture in which to spread. Writing, language, and symbolism are the modes of replication of ideas, good or bad. Sometimes they are forgotten—even good ideas—in which case replication of the meme ends. Sometimes bad or pernicious memes spread, not because they are correct: they are passed on simply because they are popular.
But here you must recognize that we cannot do anything about controlling mutated ideas (or memes) at the source because this would require silencing dissent, censoring expression, eliminating free thought, and criminalizing intellectualism—strong-arm practices that have definitively failed throughout history. Once an individual unleashes a novel idea (a cultural mutation) the social environment decides if it is viable. In other words, if we want to do anything about treating a mutation, we need to do the same thing we are doing to treat malaria: tweak the environment so that the idea no longer holds any importance.
Human intervention at the genetic level does almost nothing to prevent the ultimate cause of sickle-cell disease. The only useful intervention is testing parents to see if they carry the appropriate genetic variant. If they both test positive they can take precautions to ensure that the fertilized embryo is healthy. There is a likelihood that sickle-cell disease will be avoided due to mathematical properties of gene assortment in the sperm and egg. Sickle-cell disease is a simple Mendelian trait, which means two carriers of the gene variant will produce only one in four offspring that show the extreme form of the disease. In vitro fertilization of the egg allows doctors to detect the healthy embryos from those that are positive for sickle-cell anemia gene variant. The parents can then decide to implant the healthy embryo into the mother’s womb. But this is an individual choice, not a population fix. The parasitic infections will continue to plague the larger community. If we want to make the biggest impact treating any of these diseases we have to intervene in the environment. Managing the breeding habitats of mosquitoes, or reducing the contact between humans and the pathogen (i.e. with mosquito netting), is ultimately more effective than treating individuals one at a time. It may not eliminate the parasite, but it will prevent malaria transmission, which means fewer human infections.
Sometimes, when dealing with mutant ideas, we can adopt a similar strategy. Citizens United is able to spread its ideas because our cultural and political environment allows for it. The Supreme Court gave the members a habitat into which they could release the disease. Until the Court gets back on track and overturns its overturn, we might be in for a sustained period of tragic consequences in our political system. The best way to quell a bad idea such as “Corporations are people” is to expose its proponents and their hidden agenda. Bad ideas rarely spread when the population is educated about better alternatives.
Mutations have a hard time coping with change. The vast majority of them result in the death or inviability of an embryo. If a mutation is advantageous in any way, it will spread through the generations, eventually replacing the original trait from which it was derived. When all members of a population are endowed with the trait in mutant form, it is considered a “fixed” mutation. Once they reach fixation, they depend on constancy of the environment. We don’t know the future of challenges to the First Amendment. All it takes, however, is a “viral meme”—perhaps a catchy song, persuasive movie, political speech, or news story—to remind people of the ruthless human toll caused by certain careless corporations in our midst, and the environment may turn cold to the idea that “Corporations are people.”