Unselfishness from Selfishness: A Gene-centric View of Evolution

For generations, a population of moths lived on the pale bark of trees in a quiet forest. Most moths were light-colored, but occasionally, a genetic mutation produced a darker moth. At first, the difference seemed unimportant. Then the forest changed. Pollution darkened the tree trunks, making the pale moths easier for birds to see. Darker moths were better camouflaged, so they were less likely to be eaten and more likely to survive and reproduce. Their offspring inherited the genetic variants associated with darker coloration. Generation after generation, the frequency of those variants increased in the population. The moths did not change because they needed to survive. Instead, heritable variation already existed, and natural selection caused some variants to become more common than others. Millions of years later, the forest looked different again. And so did its moths. Evolution has never been a conscious decision. It was the gradual change in the inherited characteristics of a population across generations.

The story suggests that the environment plays a vital role in shaping the organism. Moths have changed their colors according to their environment. Of course, evolution is the underlying idea behind the change in color. The deeper question is what is being selected by evolution. Is it the individual organism, the group, the species, or genes?

A traditional way of explaining animal behavior was through group selection. The idea is that animals behave in ways that are good for their species. For instance, suppose a bird gives an alarm bell when a predator approaches. The bird's warning may attract the predator's attention and therefore put the caller at greater risk. A group selection explanation might say the bird sacrifices itself for the good of the flock.

Richard Dawkins, a British evolutionary biologist, argues that this explanation is often inadequate. Evolution doesn't reward what is good for the species. Imagine two types of birds: Type A gives alarm calls and risks itself. Type B stays silent and hides when predators approach. If Type B survives more often and produces more offspring, then the genes associated with Type B become more common. Eventually, the population could be dominated by birds that don't sacrifice themselves. This creates a problem for the simple good of species survival.

What benefits the group doesn't necessarily benefit the individual. Imagine a population in which most individuals behave altruistically. An individual who behaves selfishly could sometimes exploit the altruism of others. For example, ten animals share food. Nine share generously, and one animal takes as much as possible for itself. The selfish animal may obtain more food and therefore have more reproductive success. If its behavior has a genetic component, the genes contributing to that behavior can spread, which creates an evolutionary problem.

If evolution favours individuals that reproduce successfully, why should genuine self-sacrifice evolve?

Dawkins encourages us to distinguish between the organism we see and the genetic information it transmits through generations. You and I are organisms, but our bodies are temporary. A human being lives for a relatively short period. Genes, however, can survive by being copied from one generation to the next. So Dawkins proposes that we need to think of evolution from the perspective of the gene. This doesn't mean that genes have thoughts or intentions. He uses the term selfish gene, which implies that a gene that increases the probability of its own replication will become more common in the population.

Selfish is just a metaphor for the outcome of natural selection. Suppose gene A contributes to a characteristic that increases the organism's reproductive success and gene B doesn't. Over many generations, gene A produces more copies than gene B. From the gene's evolutionary perspective, it is as though gene A is trying to survive, but there is no conscious decision.

A replicator is an entity capable of making copies of itself. Early Earth had a huge chemical environment containing many different kinds of molecules. Initially, molecules might have formed randomly through chemical reactions. Eventually, perhaps through chemical processes, molecules arose that could somehow assist in making copies of themselves. Before replication, chemical molecules simply existed and reacted. After replication, there would be heritable information. Suppose A ---> A, then A ---> A + A, then A + A produces even more copies of A. The properties of A are being transferred to its offspring, which creates the possibility of selection. Imagine molecule B that produces fewer copies of B. After many generations, A becomes more abundant than B. Nothing wants anything; just differential replication is enough.

A successful replicator needs:

1. Longevity: It must persist long enough to be copied.

2. Fecundity: It must produce copies effectively.

3. Accuracy: Its copies must resemble the original sufficiently well.

Genes have been preserved through generations, and organisms are the vehicles through which genes interact with the environment and get copied. The bird has eyes, feathers, muscles, a nervous system, a brain, instincts, etc. They exist because, over evolutionary time, genetic variants help them to reproduce successfully. Similarly, in humans, eyes, brains, immune systems, muscles, reproductive systems, etc. are the products of evolutionary processes ultimately shaped by genetic information.

It doesn't mean genes completely determine our behavior or that humans have no free will. Genes influence organisms through incredibly complicated developmental and environmental processes. Humans learn, reason, cooperate, and make moral decisions. We can even deliberately act against biological impulses.

Consider a mother risking her life to save her child. From an individual perspective, this may look like self-sacrifice. But the mother and child share many genes. Therefore, protecting a close relative can sometimes help copies of one's own genes survive. The important insight is that what looks like sacrifice at the level of the individual may sometimes make evolutionary sense at the level of genes.

Dawkins is not saying humans are selfish because their genes are selfish. In fact, one of the interesting consequences of his argument is that a selfish gene can produce cooperative organisms. For example, parents caring for children, animals cooperating, individuals defending relatives, and social insects working together. These behaviors may look selfless at the organism level while still being explainable through selection acting on genetic information.

Darwinian evolution requires three things:

1. Copying: Something must be able to make copies.

2. Variation: The copies can't be absolutely identical. Occasionally, copying errors occur.

3. Differential survival or Reproduction: Some variants must be better at surviving or reproducing than others.

Copying errors are essential. Otherwise, there would be no evolution. If every copy is perfectly identical, there would be no material for natural selection to work on. So the imperfection of evolution is actually essential to evolution.

We often think that complicated things must have been deliberately designed. Consider an eye; it's extremely complicated. It has lenses, light-sensitive cells, nerves, muscles, and connections to the brain. It's tempting to think that someone must have designed this. Natural selection can produce apparent design without a designer. The process is blind. There is no planning department, no future goal, and no molecule thinking that I need to become better at reproduction. The molecules that reproduce successfully leave more copies. Over an enormous period of time, this simple process can produce astonishing complexity.

The first replicator need not have DNA. They could have been much simpler molecules. The exact historical details of the origin of life are still an active research area. But perhaps, through chance, once a molecule capable of making copies appeared, Darwinian evolution became possible.

Imagine a replicator that makes copies with terrible accuracy. Its descendants might actually become completely different from a replicator. It would have difficulty maintaining its identity. Now another replicator copies itself with extreme accuracy, with occasional errors. Its descendants remain recognizably similar. This allows successful characteristics to persist. Therefore, the importance of longevity, copying, and fecundity comes into play.

Resources are very important when there are replicators. Suppose the environment contains limited molecules that replicators need. Imagine both replicators A and B need resources to make copies. If A reproduces more efficiently, it may consume resources that B could have used. Competition therefore emerges naturally. Nobody invents competition. Replicators reproduce in a world with limited resources.

Suppose replicator A can make copies with the help of some chemical machinery. Now imagine another replicator B that can't reproduce independently but can exploit A's machinery. B might effectively become a parasite. For example, A builds the system that helps replication. B uses that system to reproduce itself. This creates another evolutionary problem:

How can successful replicators protect themselves from competitors and parasites?

The replicators eventually became associated with increasingly sophisticated structures that helped them survive and reproduce. Imagine two replicators: replicator A produces copies but has little protection. Replicator B produces copies and influences the construction of a protective structure. B's descendants may be better protected. Over time, structures that help replicators survive and reproduce can become increasingly elaborate. Eventually, the process leads to replicators, cells, organisms, animals, and humans. The organism becomes a survival machine. The organism is the vehicle through which replicators survive and reproduce.

Most of us think that genes exist because organisms reproduce. The truth is, organisms reproduce because genes are being replicated through them. For example, consider a bird; we think that the bird produces offspring that inherit genes. The right explanation is that genes construct bodies and use them to reproduce offspring that copy the genes. A gene is a replicator, and the body is a vehicle. A gene doesn't generally move around independently in a world. Instead, it influences the construction and behavior of organisms and how they interact with the environment.

Humans, Elephants, butterflies, oak trees, Bacterium, Fish, octopuses, etc. look completely different. But Dawkins points out that at the molecular level, life is remarkably uniform. DNA in these organisms is built from the same four basic nucleotides: Adenine(A), Thymine(T), Guanine(G), and Cytosine(C). What makes organisms different is largely the sequence and organisation of these building blocks. DNA has a four-letter chemical alphabet, but enormous sequences can be constructed from it.

DNA is a very large molecule arranged in a double helix structure. Imagine it as a twisted ladder. The sides of the ladder form the backbone, while the rings are formed by paired bases. The four bases are A, T, C, and G, with A combining with T and C with G. DNA contains information that can be copied, which makes it important from an evolutionary perspective.

DNA has two crucial jobs: replication and building the organism. DNA can make copies of itself. If a particular genetic sequence survives and gets copied repeatedly, descendants can contain versions of that sequence. DNA also contains information that helps direct the production of proteins. Proteins are extremely important because they perform many jobs, like building structures, transporting molecules, catalyzing chemical reactions, regulating processes, and controlling cellular activity. DNA doesn't reproduce itself independently. It helps construct the body that protects it and helps it reproduce.

DNA is not simply one enormous loose molecule. It is organized into structures called chromosomes. A chromosome contains DNA, and within that DNA are many genes. It is difficult to define what exactly counts as a gene in DNA. A gene is a piece of genetic information capable of being transmitted through generations with sufficient integrity. Genes can persist through copies across many generations. That is why Dawkins calls them immortal coils. He doesn't mean that an individual DNA literally lives forever. DNA molecule is eventually broken down. He means that genetic information can survive by being copied into successive generations.

Suppose two organisms compete. One dies after reproducing, and another survives for a very long time but leaves no descendants. The successful organism is the one whose genetic information becomes more represented in the future. Instead of asking, why organism behave this way? A better question is: What effect does this behaviour have on the transmission of genes?

If genes are selfish, then why don't they constantly fight with each other? Genes often have common interests. A gene that builds an eye, a gene that builds the muscle, and a gene that builds the brain often depend on thousands of other genes. Therefore, selfish genes can cooperate extremely effectively. The genes cooperate because cooperation can increase the success of the genetic information in which they occur.

If genes benefit from survival, why don't genes build organisms that live forever?

Natural selection is much stronger on traits affecting reproduction earlier in life than on traits whose effects occur much later. Suppose a harmful genetic effect appears only after an organism has already reproduced. Natural selection has less opportunity to eliminate that gene because the gene has already passed on to the next generation. Evolution favours genetic variants according to their effects on reproductive success across generations.

If genes are the important replicators, why do organisms reproduce sexually? Why not simply make a perfect copy of yourself?

Sexual reproduction is strange because you don't pass your entire genome to one child. You generally pass approximately half of your genetic material. A child gets 50% of their genes from their mother and 50% from their father. During the production of gametes, chromosomes can exchange segments that means genetic combinations are continuously being reshuffled. A copy of a particular gene can become distributed into different genetic combinations and bodies.

A gene doesn't mean a single nucleotide. A useful evolutionary gene might be a stretch of genetic information that can persist and be selected as a relatively coherent unit. For example, imagine a sequence: ABCDE. If ABC produces one useful effect and DE another, evolutionary selection can act on different portions. But if a particular combination of sequence works especially well together, natural selection can preserve that combination. So the gene is a unit of inherited information that can persist and undergo selection, rather than simply one DNA letter.

Imagine a species A that is a poisonous insect. Predators learn from its appearance that it's a danger. Now imagine a species B that evolves a similar appearance. Predators avoid species B because it resembles the dangerous species. This is called Batesian mimicry. The resemblance can increase survival and therefore the chance that those genes are passed on. A genetic change that causes a useful resemblance can spread because of its consequence for the organism. Selection acts through the effects that genes have when expressed in organisms and environments.

If every animal is trying to maximise its own genetic success, shouldn't animals constantly attack one another? Imagine two animals competing for a territory. There is food inside the territory. Both want it. One possibility is: fight until one animal is killed or seriously injured. But the fighting is dangerous. Even the winner could be injured. An injured animal might have difficulty finding food, become vulnerable to predators, fail to reproduce, and spend energy recovering. Therefore, a fight can be extremely costly to both sides. Natural selection can consequently favor animals that have mechanisms for avoiding unnecessary fights.

Imagine a meeting of two animals. Each has different possible behavioral strategies. For simplicity, let's assume the hawk is aggressively competitive. If it wants something, it fights. It continues fighting until it wins or gets seriously injured. On the other hand, the dove is peaceful. It displays and threatens, but doesn't engage in serious fighting. If the opponent becomes seriously aggressive, the Dove retreats.

Consider a hypothetical example where two animals are competing for a valuable resource. Let's assign some imaginary values. The resource is worth +50. Winning a fight gives you the resource. But being injured costs -100.

Hawk vs Hawk: Both fight aggressively. Eventually, one wins. The winner gets +50, and the loser gets -100. There is therefore a serious risk.

Hawk vs Dove: The Dove doesn't fight seriously. The hawk gets the resource. Hawk: +50 and Dove: 0.

Dove vs Dove: Neither fights seriously. They may display or wait. Eventually, one gets the resource. The benefit is divided in some way. The best strategy depends on what the other animal is doing.

Suppose every animal is a Hawk. Then being a hawk can be dangerous. It's because there are frequent encounters with other hawks. The constant fights are very costly. Now imagine almost everybody is a Dove. A hawk entering this population can do extremely well. It can exploit the peaceful doves. So, the success of a strategy depends on how common other strategies are.

John Maynard Smith gives an idea of evolutionary stable strategies(ESS). An ESS is a strategy that, once established in a population, can't easily be invaded by other alternative strategies. It's a behavioral strategy that works well against the strategies currently present in the population and can't easily be replaced by a mutant strategy.

If everyone is aggressive, then behaving aggressively is not the best strategy. Everyone fights with everyone. The population experiences injuries, wasted energy, deaths, and lost reproductive opportunities. An individual that adopts a somewhat more cautious strategy might actually do better. Natural selection doesn't necessarily favor maximum aggression. It favors whatever strategy produces greater genetic success. Sometimes aggression is advantageous, and sometimes restraint is advantageous.

Imagine two animals fighting over food. Food gives +10, but fighting injury costs -50. It's not sensible to fight over the food because the downside is huge. Now change the situation where food gives +1000, and injury costs -10. Fighting makes sense here. Animal aggression depends on the cost-benefit structure.

Many animals don't attack immediately. Instead, they may display their size, make noises, show their teeth, spread feathers, threaten, etc., to obtain the essential information without paying the cost of actual combat. For example, two deer may confront each other. Instead of immediately killing each other, they may assess: How big, strong, or dangerous are you? The contest ends without serious injury. The stronger deer gets the territory, and the weaker deer avoids injury, but both survive. This is much better for both animals than a deadly fight.

The basic rule is: fight aggressively when you are the owner of a territory and retreat when you are the intruder. Imagine two animals encounter each other. Animal A owns the territory and behaves aggressively. Animal B is an intruder and gives way. This strategy is remarkably successful because the owner has more to gain by defending the territory, while the intruder may avoid a costly fight. This can produce a stable system of territorial behavior.

The same strategy can be beneficial in one environment and harmful in another. Therefore, the success of any strategy depends partly on what everyone else is doing. Moreover, the strategy that is more likely to spread the genes becomes common in a population over an enormous period of time. This is the foundation of evolutionary game theory.

Kin selection is an idea where a gene can spread not only by helping the individual carrying it reproduce, but also by helping copies of that gene in relatives reproduce. Natural selection favors genetic variants that, on average, cause organisms to behave in ways that increase the representation of those variants in future generations. Evolution doesn't necessarily favor a behavior because it benefits the individual. For example, an organism reproducing and passing its genes to its children is an instance of direct reproduction. On the other hand, an organism helping a close relative that carries copies of the same gene is an instance of indirect reproduction. Both routes can matter from the gene's perspective. This is called inclusive fitness.

Suppose an animal gave up an opportunity to reproduce but saves several close relatives from death. It may appear to have sacrificed its own fitness. But if those relatives carry many copies of the same genes, the gene responsible for helping the behavior may still increase its frequency. You and your biological child share, on average, about 50% of genes. You share 25% of genes with a half-sibling and 12.5% with cousins. These are average possibilities, not statements that every pair shares exactly those percentages. So if a gene causes you to help your brother, that behavior may help copies of that gene survive in your brother's body.

The logic is beautifully captured by Hamilton's rule: r * b > c, where r is genetic relatedness between the helper and recipient, b is the benefit to the recipient, and c is the cost to the helper. A helping behavior can be favored by natural selection when r * b > c. For example, suppose helping your brother costs you the equivalent of 1 offspring. Your brother gains the equivalent of 3 offspring because of your help. Since siblings have r = 0.5, we get rb = 0.5 * 3 = 1.5. The 1.5 is greater than 1. Therefore, the behavior can be favored because the genetic benefit gained through the relative exceeds the cost to the helper.

Natural selection doesn't operate according to the rule, "Always help the relative." The actual evolutionary logic is more sophisticated: "Help when the expected genetic benefit of helping is greater than the cost." An animal doesn't need to know that this individual shares 50% of my genes. Evolution can produce mechanisms that correlate with relatedness. For instance, animals may recognise their offspring, their siblings, nest mates, colony members, individuals with familiar smells, and individuals from their own social group. If these cues reliably correlate with genetic relatedness, natural selection can favor helping behavior toward those individuals.

An animal sometimes helps unrelated individuals because of reciprocity. It is based on the principle of "I help you today, and you help me tomorrow." Suppose two unrelated individuals repeatedly interact. Animal A helps animal B today. Later, animal B helps A. Over many interactions, both can benefit. So what looks like altruism at one moment may actually produce a long-term advantage. This is sometimes known as reciprocal altruism. The key condition is repeated interaction. If you help someone once and never encounter them again, reciprocity is difficult.

Let's see another important evolutionary problem. Suppose cooperation evolves and most of them cooperate. But some of them accept the help but won't help when you need them. These individuals are cheaters or free riders. They can potentially receive the benefits without paying the cost. If cheating becomes too common, cooperation can collapse. This creates an evolutionary arms race between cooperators and cheaters. Natural selection can therefore favor mechanisms that detect and punish cheating. Therefore, evolution can produce complex behavioral strategies involving cooperation, retaliation, recognition, punishment, forgiveness, cheating, etc. Apparently complicated social behavior emerges from simple evolutionary principles.

Conclusion: A selfish gene can promote seemingly altruistic behavior if that behavior helps it spread across generations. What appears altruistic from an individual’s perspective can make more sense when viewed from the perspective of genes. Much of the behavior we observe in humans can be understood through the lens of evolutionary game theory. This perspective can help us better understand human nature and develop healthier relationships with others.

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Photo by Vitaly Gariev on Unsplash