PDF Summary:The Selfish Gene, by Richard Dawkins
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Richard Dawkins, an evolutionary biologist and author, Dawkins argues that biology’s focus on organisms is misguided, and that life should instead be considered from the point of view of individual genes trying to perpetuate themselves through countless generations.
Though the book begins with the premise that biologists think too large (organisms instead of genes), it ends with the surprising idea that they think too small—that genes have much greater impacts on the world than simply creating bodies to inhabit. Dawkins offers compelling arguments for why we should think about biology as ranging from the microscopic to the wider world.
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Scientists have simulated this process using computers and game theory. By assigning arbitrary point and penalty values to different outcomes such as winning a confrontation, being injured, or wasting time on a lengthy contest, and programming in various strategies for the virtual “animals” to use, the simulation can run until the population stops shifting in any significant way. These simulations help scientists to find and understand the ESS.
Limited Resources May Cause Conflicts of Interest
Because Earth is a finite world with finite resources, there’s a natural struggle between the creatures who inhabit it to get those resources. This competition extends to family members, including the struggle between parents and their children for exactly what proportion of the resources each child should get. The parent will want to distribute resources for the best possible genetic payoff—in other words, the maximum number of surviving offspring. However, each child will be interested in getting more for itself. Therefore, the child will often try to trick its parents into believing it needs more resources than it’s getting.
Also, if there can be conflicts of interest between parents and children—who share 50% of the same genes—then there should be severe conflicts of interest between mates, who have no relation to each other at all. Genetically speaking, each is only valuable to the other in terms of their shared offspring. Each wants as many surviving children as possible, but they will naturally disagree on who should have to invest the resources to raise those children.
There are benefits to each of two conflicting situations: staying with your partner for as long as possible, and abandoning them with the child before being abandoned yourself. A mated pair that stays together can split the resource cost of raising their offspring. However, a parent who abandons their mate and offspring gains a significant advantage—if they can be reasonably sure that the remaining mate will successfully raise the child or children.
Worth noting in this situation is that the female will naturally be more invested in the offspring. This is because she contributes the larger and more resource-intensive egg cell and, in many species, because she takes on the cost and risk of pregnancy and birth. It will be much more difficult for the female to produce another offspring than the male, who could easily find another mate and impregnate her.
These two situations, parent vs. offspring and male vs. female mates, have led to a huge array of evolutionary tools and strategies. A child may use various tactics to try to get more than its fair share of the resources. For example, a common tactic among young birds is to cry more loudly than the others in the nest. Since the volume of a cry normally corresponds to how hungry the bird is, a louder hatchling can trick its parents into thinking it’s hungrier than the others, causing them to give it more food at its siblings’ expense.
For mates, many species of animals have long, intricate courtships to get both the male and female heavily involved before they actually reproduce. We mentioned before that, in theory, a male could simply leave and impregnate another female right away. However, if he knows he’ll have to go through the entire courtship again, it’ll be more worth his time to stay with the mate he already has.
Group Altruism and the Evolution of Culture
Many types of animals move, or even live, together in groups. Some advantages of this are obvious. For example, prey animals gain some protection from predators by living in groups. Meanwhile, predators like hyenas can bring down much larger prey by working together, so it benefits them all even though they have to share the food.
Another example is birds, many of which fly in formation and switch leaders frequently to reduce turbulence and make travel less tiring. However, birds have also been observed giving alarm calls to warn of predators, at some risk to themselves. This apparent act of altruism may ultimately be an act of selfishness—in fact, considering the selfish gene theory, it must be.
By the simple truth of natural selection, we can infer that giving that alarm call is more beneficial to the individual’s genes than not giving it would be. There are any number of possible reasons for this.
For instance, if a bird simply flew away upon spotting a predator, it would lose the advantages of living in a flock. If it froze and hid, but the rest of the flock kept moving around and making noise, that would draw the predator closer to the individual anyway. Therefore, it would be best to call a quick warning so the entire flock can hide. Also, there’s the simple likelihood that by taking a small risk to itself, the individual giving the call can protect many of its relatives. Finally, we can infer that if one of these birds calls to warn the others, that kindness will be repaid later by the others.
This is one form of reciprocal altruism: Two or more animals showing each other mutual altruism. Another common example is communal grooming. This example is especially interesting because there is a delay between one act of altruism and the act being repaid—pulling a harmful parasite off another individual doesn’t help you until you have a parasite to be pulled yourself.
The cost of grooming another member of the population is minuscule, but it’s still greater than zero. Therefore, among species that participate in communal grooming, there must be greater benefit than cost for doing so. One possible explanation is that members of the population evolved the ability to hold a “grudge”; that is, they refuse to groom selfish individuals who don’t groom others. This would naturally drive down the number of selfish individuals as they fall victim to parasites.
Ideas Spread Like Genes
Interestingly, ideas and behaviors can be observed to spread through populations and evolve much like genes do. Certain songbirds, for example, are known to learn their songs by imitating birds around them, rather than having them coded in by genes. However, sometimes birds will make a mistake and give rise to a new song. That song, in turn, is picked up by others and spreads throughout the population. If the replicator unit of biology is the gene, then the replicator unit of ideas could be called the meme—from the Greek mimema, meaning “that which is imitated.”
Among humans, the spread of ideas is more pronounced and much easier to recognize. A catchy song is a type of meme, as is a popular slogan or a political stance. God is one of the most successful memes in all of history—while it’s not clear how the idea of God originated in the “meme pool,” so to speak, it has been spread by stories, songs, art, and rituals to nearly every part of the world for thousands of years.
Culture and memes don’t seem to have any inherent survival value. It’s more likely that they’re side effects of group-focused evolutionary traits such as those discussed at the beginning of this section.
Extending the Phenotype
We began with the premise that biologists think too large (organisms instead of genes), but it’s also possible that they think too small—that genes have much greater impacts on the world than simply creating bodies to inhabit.
To look at biology in a new way requires that we consider what might be called the extended phenotype. Phenotype typically means the physical effects that genes have on the body they inhabit—for example, blue eyes or long legs. However, it’s not much of a stretch to extend the definition of phenotype beyond the individual, to include the impact on the world. This could be called an extended phenotype.
While phenotype typically refers to a creature’s physical body, genes don’t directly affect such things; rather, they change the internal workings of cells, which eventually leads to different traits in the body. Therefore, saying that the organism’s body—but not its impact on the wider world—is a result of those genes is fairly arbitrary.
Some examples of this extended phenotype could be bird nests and beaver dams. Though it sounds strange to say, there are genes “for” certain building materials and construction styles—phrased another way, there are genes that cause the animals to build structures in those specific ways. Even a lake that was formed by beavers damming a river could be considered part of those beavers’ phenotypes.
It’s easy to see the obvious ways that organisms interact with each other: competing for resources, predation, mating, symbiosis, and so forth. However, with an extended phenotype, it becomes clear that there are countless different ways that organisms—or, more accurately, genes—impact each other and the world around them. The problems and opportunities that arise from this gene-centric view of the world are explored in much greater detail in Dawkins’s book The Extended Phenotype.
Biologists Often Ask the Wrong Questions
Many biologists make the mistake of focusing their questions and their studies on the organismal level: They ask why an organism does something, or behaves a certain way. In fact, it’s quite common for biologists to say that DNA and RNA are tools organisms use to replicate themselves—which, in light of what we’ve discussed so far, is the exact opposite of the truth.
Organisms don’t replicate themselves at all (except in the relatively rare case of asexual reproduction). Given that the “purpose” of life is replication, it seems clear that organisms are tools that genes use to replicate themselves.
Starting from the genetic level, then, one might ask why organisms as we know them should exist at all. The simple truth is that organisms don’t have to exist. They exist on Earth because that’s what evolution happened to favor in this particular environment.
It’s helpful to remember that, at the most basic level, we’re dealing with replicators that aren’t so different from those found in the primordial soup eons ago. The only thing that must exist in order for there to be life is some form of replicator molecule. Replication is both the beginning and the purpose of life.
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PDF Summary Chapters 1-2: The Purpose of Life
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Selfishness and altruism both have roots in biology and evolution. Several famous and influential books, such as Robert Ardrey’s The Social Contract and Konrad Lorenz’s On Aggression, have already explored selfishness and altruism in nature. However, those books are fatally flawed because the authors misunderstood the point of evolution. Ardrey, Lorenz, and others thought that evolution existed for the good of the entire species. However, the common belief among biologists today is that evolution is about the survival of the individual.
(Shortform note: The terminology is a bit confusing here, since evolution works on the population level and not the individual level. However, as a population evolves, each individual in it has a better chance to survive and pass on its genes.)
“The good of the species” is a common misconception. It comes about because most of an animal’s life is devoted to reproduction, and most of the selfless acts an animal performs are for its offspring. Therefore, it seems like creatures act as they do in order to continue the species.
Furthermore, by slightly twisting Darwin’s theory of evolution, a logical—but wrong—conclusion can be drawn:...
PDF Summary Chapter 3: What Are Genes?
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There are a number of factors that affect how long a given gene lasts, even if the creature does successfully reproduce. These are detailed in the next subsection. Theoretically, a gene could replicate itself through countless generations and “survive” indefinitely.
In short, it could be said that genes are responsible for their own reproductive success. Going one step further, it could be argued that replication is the very purpose of genes, dating back to those first primordial replicators.
The “Paradox” of Sexual Reproduction
If genes truly exist to replicate themselves, it would seem like sexual reproduction isn’t the best way to do it. Sexual reproduction takes a great deal of time and resources and, most significantly, only allows each parent to pass on half of their genes. This apparent paradox leads many people back to the group-focused idea of evolution, wherein the good of the species is the ultimate goal.
However, if there are individual genes that do well in an environment of sexual reproduction (such as genes for qualities that help attract mates), that in itself could explain why sex exists and resolve the paradox. Therefore, from the viewpoint...
PDF Summary Chapter 4: How Genes Lead to Behaviors
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One might question, if the body is really just a complex survival machine for genes, why they don’t control it directly. However, they can’t do that because the lag would be much too great. As mentioned in Chapter 3, genes code for proteins. By the time those proteins were made and incorporated into the body, whatever stimulus they were responding to would be long over.
Therefore, muscle movements are controlled and coordinated by the brain, which is like the processing unit of a computer. Like a computer, the brain interprets complex inputs and determines the appropriate responses.
The movements are then timed by neurons, or nerve cells, which control and transmit signals a bit like transistors do in electronics. Neurons are specialized cells with long, thin projections that carry signals. There is often a long central projection called an axon, which bundles with other axons to form nerves. (Shortform note: The Selfish Gene uses the older spelling “neurone,” but it refers to the same thing.)
**One of the most notable things about animal behavior is that it seems purposeful—that is, the behaviors aren’t just programmed responses designed to aid survival, there seem...
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Learn more about our summaries →PDF Summary Chapter 5: Aggression and Selfishness
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Therefore, before animals fight in earnest, they have to somehow weigh the risk against the benefits. Fighting another member of one’s own species is extremely risky, since they’re likely to have similar physical abilities. In fact, animals of the same species usually “fight” in a way that’s comparable to boxing or fencing: There are rules, it’s clear when the bout is over and who won it, and (barring an accident) neither party gets seriously hurt.
Game Theory and Evolutionarily Stable Strategies
(Shortform note: Game theory is the study of strategic decision-making through mathematical models.)
Populations of animals will naturally tend toward an Evolutionarily Stable Strategy, or ESS. The ESS of a population is the most stable possible configuration of members; by definition, any member of the population who doesn’t conform to the ESS will not be as successful as others.
For example, imagine that a hypothetical species has two possible strategies when confronted with a rival: Fight or bluff. Furthermore, imagine that each member of that species engages in only one of those behaviors—the same one every time without fail.
If two fighters meet, they will fight...
PDF Summary Chapter 6: Why Animals Help Their Relatives
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If g is the number of branches traveled, the relatedness would be (1/2)g
That equation assumes only one common ancestor. If there are more, multiply the result by the number of common ancestors in the most recent generation that has them.
Recognizing Kin
Naturally, the previous section raises the question of how animals recognize their relatives—or even whether they do. It’s possible that some animals recognize each other simply by appearance, and act altruistically toward animals that resemble them. Others might act altruistically toward any member of their species that happens to be nearby. In that case, we could assume that the odds of any given member of the species being a relative are good enough to make the altruism worth the risk. These behaviors arose due to common situations in nature, and they can misfire—or be made to misfire, like when farmers make nesting hens sit on eggs that aren’t their own.
An interesting evolutionary arms race can be seen between certain species of songbirds and cuckoos who lay eggs in their nests, trying to trigger just such a misfire. Cuckoos try to trick the songbirds into hatching their eggs by laying them in...
PDF Summary Chapter 7: Animal Reproduction: Bearing vs. Caring
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Starvation is one major factor in keeping animal populations under control. If animals reproduce too quickly for an area to support, naturally many of them will starve. However, starvation cannot fully explain how animal populations stay under control. If starvation were the only control set on population size, scientists would expect all creatures to work like lemmings do: Their numbers would increase exponentially until the region couldn’t support them, then suddenly crash as most of them starved.
Therefore, it’s clear that there are methods limiting birth rates as well as death rates—animals don’t have infinite numbers of offspring. The question is not whether birth rates are controlled, but why they are controlled.
The group-selection theory would say the reason is altruistic: Animals regulate their birth rates for the good of the entire population. The selfish gene theory would say that it’s selfish: Animals regulate their birth rates because it gives them and their offspring the best chance of survival.
The Altruistic Theory of Birth Control
Wynne-Edwards’s theory says that animals have natural rules and guidelines that keep their populations in...
PDF Summary Chapters 8-9: Limited Resources and Conflicts of Interest
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Also, many animals will not care for the “runt” of a litter, because it is less likely to survive and reproduce than others. In extreme cases parents may even feed the runt to its siblings, or eat it themselves. Though it seems contradictory, a selfish gene may even cause runts to give up and die in favor of their stronger siblings, so as not to drain resources from individuals with better chances of survival.
There comes a time when it makes sense, from a selfish gene’s perspective, for the parent to stop having children and focus on raising more distant relatives. If a child would have less than a 50% chance of survival—such as if the animal is too old to effectively raise more offspring—then mathematically the animal should devote its efforts to raising a grandchild instead. The grandchild is more distantly related, but has a much better chance of surviving to reproduce. Of course the animals don’t consciously calculate these odds, these behaviors are programmed by genes that have survived and outcompeted their alleles. As a side note, this may be a genetic explanation for menopause in humans.
**This logic also applies to siblings who have to compete with one another...
PDF Summary Chapter 10-11: Populations and Culture
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The cost of grooming another member of the population is minuscule, but it’s still greater than zero. Therefore, among species that participate in communal grooming, there must be greater benefit than cost for doing so. The obvious explanation is that the benefit of having a parasite pulled off of you is much greater than the cost of pulling one off of another individual. However, another possibility is that members of the population evolved the ability to hold a grudge; that is, they’ll refuse to groom selfish individuals who don’t groom others. Such behavior would naturally drive down the number of selfish individuals as they fall victim to parasites.
Altruism and Selfishness in Insects
Much more extreme examples of altruism are seen in social insects like ants and bees. In a beehive, for instance, the vast majority of the bees are workers who can’t breed and will give their lives to protect the hive.
From the perspective of a selfish animal, such behavior makes no sense. However, from the perspective of a selfish gene, it is easily explained with two key facts. First, the workers are sterile—they can’t pass their genes on directly, so dying is no great loss....
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PDF Summary Chapter 12: The Prisoner’s Dilemma
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There were a number of complex strategies submitted for this tournament, some of which were quite cutthroat. However, the surprising winner of the tournament was a simple program called Tit for Tat. This program always played Cooperate on the first round, then for each round after that it simply copied what its opponent had done last. This made it so cooperative strategies were rewarded, while aggressive strategies were punished. Afterward, Axelrod calculated that a so-called “Tit for Two Tats” program would have done even better; such a program wouldn’t Betray until having been betrayed twice in a row itself, and would therefore have avoided some penalizing loops that Tit for Tat got caught in.
Out of 15 programs submitted, eight of them were programmed to never Betray first, and those eight “nice” programs had the highest scores. The aggressive strategies all scored significantly lower than their cooperative counterparts. The weakest of the top eight was an “unforgiving” program, which played Cooperate until the first time it was betrayed, and then played Betray every round after. This meant that it couldn’t break out of penalizing loops the way the other cooperative...
PDF Summary Chapter 13: The Far-Reaching Effects of Genes
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An Extended Phenotype
To look at biology in a new way, starting from the genetic level, requires that we consider what might be called the extended phenotype. The usual definition of phenotype is the effect that a particular gene has upon the body it’s housed in—for example, blue eyes or wrinkled peas. However, phenotypes should really be considered in terms of the total effect they have on the world.
It may be the case that a particular gene only impacts the body it’s in, but there’s no reason why that should be key to the definition of phenotype. Whatever effect genes have on physical characteristics is incidental—their real impact is on the chemical processes inside the body (remember that a gene’s true function is to act as a blueprint for a protein). Therefore, going one step further by talking about the effects of genes on the world around them is not as much of a stretch as it first seems.
Examples of phenotypes that extend beyond the bodies they’re in are bird nests and beaver dams. Though it sounds odd to us, biologists should think in terms of genes “for” certain building materials and styles of nest, dam, and so on. Genes that caused the organisms...