The extended selfish gene – Richard Dawkins (Summary)

Definitions:

  • Selfishness = Bad for others, good for me
  • Altruism = Good for others, bad for me

Aim of the book: Explain selfishness and altruism through the lens of evolution.

What the book is NOT about:

  • How we SHOULD behave (It is about how we DO behave)
  • Nature/nurture problem. However, he says we can learn altruism, but it is hard with our selfish genes
  • Psychological motives (Whether people have secret or selfish motives)

Main argument:

  • Since our genes have survived for millions of years, we can expect them to be selfish
    • This often manifests itself as a selfish individuals
      • Natural selection favors those genes that manipulate the world for their own success
        • Blacheaded gulls nests are often close, and when one turns its back to its chicks, sometimes another one swallows one of them whole
        • Female mantises eat the male just after mating, starting with the head.
        • Emperor penguins in the Antarctic try to push each other in the water, to see if there are dangerous seals.
      • But…
        • Genes also need to work together with the current gene pool.
        • Tit-for-tat is one of the best strategies in the prisoners dilemma
          • But universal love and welfare of the species doesn’t make sense in an evolutionairy perspective

Alternatives to main argument:

  • Group selection: Groups with altruistic members tend to survive
    • The idealistic side of ourselves likes the thought of group selection.
    • Arguments against group selection
      • But in those groups, there will be selfish rebels, and natural selection will favor them
      • And how big would those groups be? Family? Species? Genera? Order? Classes? All organisms?
      • Group “selection” can also be explained in terms of individuals that are chosen because they are compatible with the group.

Historical background for argument:

  • Atoms tend to form specific patterns called molecules
    • e.g. hemoglobin consists of 574 amino acids in the same EXACT shape each time!
      • We have over six thousand million, million, million hemoglobin molecules in our body
  • At some point came the replicator, that could create copies of itself.
    • These replicators must have spread faster than the stable molecule configurations that came together by chance.
    • Laboratory experiments that mimic the chemical conditions of earth before life had created purines and pyrimidines, which are the building blocks of DNA.

Replicators:

  • Replicators are our real “ancestors”
  • Because the replicators can survive for so long, they can potentially have a bigger impact on the universe.
  • 3 factors that can make a specific replicator more numerous
    • Longevity
    • High frequency of replication
    • Low error rate (When replicating)
  • We live in a competitive environment with limited ressources, so the replicators needed survival machines
    • These survival machines evolved over billions of years to become: Animals, plants, viruses, bacteria.

Evolution:

  • Sometimes replicators makes mistakes, and this is what made evolution possible
    • For something to be evolve by natural selection/darwinian adaption there needs to be a genetic variation for that thing.
      • But there are also other ways than natural selection, by which things can evolve.
  • When there is strong selection for some trait, the genetic variation that caused that trait to evolve is likely to dissapear.
  • A gene “for” some trait may not be the original cause for the development of that trait
    • Maybe some other genes were responsible for developing the trait, and then a new gene suddenly “destroys” that trait. Then the allele for that new gene could be seen as a gene “for” that trait.
  • Always ask: “What effect will this characteristic have on the frequency of specific genes in the gene pool?”

DNA/Genes:

  • DNA is long chains of the 4 nucleotides A, T, C, G
  • Genes = Sequence of DNA that codes for something
  • Genes are one type of replicator.
  • His definition of genes:
    • ANY PART of chromosomes that passes through many generations in the form of copies
  • Other things being equal, a specific gene might indirectly affect behavior in some specific way.
  • With a few exceptions, all human cells have a complete copy of our DNA (Inside the nucleus)
  • All humans started out as one original cell with a copy of their DNA inside it, that is then replicated
  • DNA indirectly influences the development of our bodies, through its supervision of protein creation
    • Each gene can affect many parts of the body, and each part of the body can be affected by many genes.
    • The effect of one gene depends upon the other genes that are present.
      • Some genes control other genes.
      • Some traits require multiple genes to work together
    • Characteristics that we acquire through our life does not affect our genes.
  • Passing on of genes:
    • Any individual (Except identical twins) is a unique combination of genes, and some of the genes are passed on through many generations.
    • Of our 46 chromosomes, there are 23 pairs, where one side of the pair came from our father and the other side from our mother, and they both code for the same things (e.g. eye color)
      • Some are dominant, while others are recessive
      • Different ways genes can change (Small genetic units are less likely to be affected by these):
        • Point mutation: Changing in a single point
        • Inversion
        • Inversion, and placement in another chromosome.
        • Cross-over
          • Each of the 23 pairs of chromosomes is a unique mix of the DNA from the father and the mother, because of the cross-over of genes between pairs of chromosomes.
          • Genes are separated by start and end symbols (Coded in the four nucleoids) , but cross-over doesn’t respect these boundaries.
          • Shorter genetic units are more likely to survive because they are less likely to be changed by cross-over.
  • Why choose genes as the unit of natural selection?
    • To have a big impact, something must:
      • Have high longevity, and high rates of replication with a low error rate
      • Exists in many identical copies.
    • They are immortal, compared to us.
    • They approach indivisibleness, by rarely being divided.
    • Bigger groups like individuals, groups, and species are temporary aggregations, so they are not stable entities.

Competition/Aggression/Game theory:

  • We are more likely to compete with individuals from our own species, because we are more likely to compete for the same resources.
    • Especially if we are the same sex, and compete for mating partners.
    • Because we compete less with other species, our territories and theirs can overlap.
  • We often use threats and bluff instead of killing
    • Trying to kill someone might kill yourself or you might lose valuable time & energy.
    • Killing someone else might benefit one of your rivals more than yourself.
  • Evolutionary stable strategy (ESS): A set of strategies, where once they are adopted by a population, no selfish individual can corrupt the system to their own advantage.
    • Different fight strategies:
      • Hawk: Fights as hard as possible until severely injured or death
      • Dove: Only threatens, but runs if a fight starts
      • Bully: Acts like a hawk, until someone fights back
      • Retaliators: Does the same as the opponent, but acts as doves when they meet each other
        • Only this one is ESS
    • Humans can have other strategies than ESS if we can see that it will benefit us in the long run
      • But there is still a risk of someone exploiting the system to their own advantage.
    • ESS: When some are known to be larger/smaller than yourself:
      • If larger: Run away
      • If smaller: Fight
    • ESS: When memories of past fights exist:
      • People who lose will rate their fighting skills lower and create a self-fulfilling prophecy of losing more, and a dominance hierarchy will develop.
    • When an ESS exists among genes, then new genes have to be compatible or create a new ESS.

Altruism towards family is selfishness between genes:

  • The gene pool becomes filled with genes that program their survival machines to be altruistic enough towards other survival machines with the same genes (Family), but not TOO altruistic! (Depends on degree of relatedness)
  • Rule of thumb for calculating relatedness to someone else:
  • g = generation distance
    • Find the most recent common ancestor (Which could be A or B)
    • Start from A or B
    • Count generations up to the common ancestor
    • Count generations down to the other person
    • e.g. brother = 2, parents = 1, grandparents = 2
  • c = common ancestors (2 if there both is a mom and dad)
  • Examples of results from applying the calculation:
    • 1: Identical twin
    • 1/2: Brothers, sisters, parents, children
    • 1/4: uncles, aunts, nephews, nieces, grandparents, half brothers, and half-sisters
  • But how can we know that we are related to someone else?
    • If they look like us
    • How altruistic we are doesn’t depend on our actual relatedness to family, but our expected relatedness!
      • e.g.
        • Me > many brothers
          • Because even though 3 brothers will contain 3*0.5=1.5 times of your genes, you are more certain that you contain the same genes as yourself than that your brothers does.
        • Motherlove > Father love
          • A mother can be more certain that it’s her own children
        • Maternal grandmother > Paternal grandmother
          • Same argument as for “Mother love > Father love”
        • Maternal grandfather = Paternal grandmother
          • Same argument as for “Mother love > Father love”
        • Uncle on mothers side > Uncle on fathers side
          • Same argument as for “Mother love > Father love”

Is animal birth control altruistic or selfish?

  • Altruistic (Group selecton argument)
    • Groups where birth rates are restrained doesn’t use up the food supply, so they don’t go extinct.
      • The purpose of territory and dominance hierarchies is to decide who should reproduce and who shouldn’t, for “the good of the species”.
  • Selfish (Gene selection argument)
    • Genes that program for having the optimal amount of children (Not so many that they starve), becomes more numerous in the gene pool.
      • Unless the individuals live in a welfare state

Battle of the generations:

  • Parental investment = Investing in some family member at the cost of another
  • Should mothers have favorites?
    • If she can only save one, she should save the oldest, because the youngest takes more parental investment to get to the same level
      • But if the older can save himself, she should take care of the younger
  • Siblings selfishness/Altruism
    • Each child should compete for the parents ressources, because each of their siblings on average only has 50% of their genes in common with the child, while the child itself has 100% genes in common with itself.
    • Each child “should” be altruistic to a specific sibling, if that sibling will benefit twice as much from a given ressource.
    • If you have less than 50% the success of your siblings, it might make sense to die, so your parents have more ressources for the other siblings.

Couples:

  • Male vs. female:
    • Male = Small mobile sex cells
    • Female = Large sex cells
    • Som species doesn’t divide into males & females, so they can all reproduce with each other.
    • Throughout its life, any given gene will on average spend half its time in male bodies and the other half in female bodies.
    • Mechanics of sex determination: Eggs can produce both, while half of sperm cells are male-producing and the other half is female-producing.
    • Males are less careful about who they copulate with, because compared to women, there are no cost to them.
      • It’s weird that in western culture women care more about physical attractiveness than men, even though it’s the men that should be competing for the women.
    • Couples don’t share any gene, but each have 50% of their genes in each of their children.
  • Ideal male/female ratio?
    • According to group selection, if each man can keep 100 woman pregnant and having babies for the rest of their lives, we should have 1 man per 100 women, since the rest is a ressource waste.
    • Having an equal number of males/females is an evolutionary stable strategy.
      • If we got more females than males, than it would be better to get a male, since they now on average can get more children.
      • If we got more males than females, than it would be worse to get a male, since they now on average can get less children.
  • Women exploitation:
    • Monogamy is not natural for men, but is probably enforced by culture.
    • The ideal for the male/female would be for the other to take care of the child
    • Women invest more from the start because of her big nutritious egg cells, so she stands to lose more, and therefore invest even more (Incubation in stomach, milk etc.)
      • Therefore the father is the most likely to abondon the mother/child
      • In some birds it’s only the mother who takes care of the child.
    • How can women avoid being left/exploited?
      • Play hard to get for a long time, so only the faithful remains.
        • Some females may require a nest to be build or some other investment
          • This way the female isn’t the only one to have invested in the child from the start, so the male is more likely to stay.
        • It is an evolutionairy stable strategy that only some percent of woman play hard to get, and only some percent of men are faithful.
  • The he-man strategy: Some females only copulate with men with the best genes, which they judge by:
    • Ability to survive
      • Being old (They have survived for many years)
      • Big muscles & long legs
    • How attractive the male is to other females
      • So the characteristics that are attractive is usually something useful to begin with, but then females can start to be attracted to them, because others are attracted to them, even when it isn’t useful anymore.
  • Taking care of adopted babies
    • For a father it makes sense to kill his step-sons.
      • Another strategy is an engagement period, where he isolates her from other men, to make sure babies are from him.

Animals living in groups:

  • If predators go for the preys in the outside of the herd, then the selfish animals in the herd will move towards the center.
  • Why does alarming bird calls make sense?
    • To save family
    • The group must not die, because it’s a valuable resource.
  • Many social insect can be divided into reproducer individuals and workers
    • The reason workers seem so altruistic, is because they are sterile, and the reproducers they help are from their family.
  • Some plants/animals live in symbiosis, where they live of each others strengths, and evolve traits that are good for each other.

Meme’s:

  • Meme = Cultural transmission/Imitation.
    • E.g. ideas
    • Culture = Many memes
  • Memes can survive because of:
    • Psychological appeal.
  • Similarities to genes:
    • 3 factors that can make a specific meme more numerous
      • Longevity
      • High frequency of replication
      • Low error rate
    • Some meme’s help other meme’s survive
      • Religion & hell fire
      • Religion & blind faith
      • Celibacy can give priests more time to influence other people into religious beliefs.
    • New meme’s have to fit into the meme pool.
  • Differences from genes
    • Competition
      • Meme’s compete for our attention
    • Cultural evolution is faster than genetic evolution (Science, art, language, religions, technology)
    • Meme’s like religion and music doesn’t need survival value to exist, but just people who will imitate them.

Why altruism can make sense in iterative games of prisoners dilemmas:

  • Prisoners dilemma
    • Basic idea
      • Two potential prisoners can either confess (Cheat) about the other potential prisoner or don’t confess (Cooperate).
      • The best sum for both is by not confessing (Cooperation).
        • But it’s better for each individual to confess (Cheat), no matter what the other individual does
    • Iterative prisoners dilemma
      • It will be best for both to cheat, no matter what the other does, but if they both keep doing that, then they will keep “losing”.
      • 2 Tournaments were created with various strategies about when to cheat and when to cooperate:
        • Tournament 1:
          • 15 Strategies were simulated in a computer program
            • 8 were nice = Only cheating if the other one does
              • These were top-scoring, with “tit for tat” in the front.
            • 7 were evil = Cheating even if the other one doesn’t
              • These were the lowest-scoring
            • Forgiving strategies were better (Not holding a grudge)
              • They didn’t end up in long rounds of both not cooperating and thereby losing points.
            • Envious strategies did worse (Wanting to do better than the opponent, rather than both winning)
        • Tournament 2:
          • 61 strategies
          • They knew that there would be many “nice” and “forgiving” strategies
            • Many nasty strategies were developed, so tit for tats wouldn’t have won this round.
            • But the nice strategies still did better
              • The success of a strategy depends on the other strategies used.
    • When can nice, forgiving, non-envious strategies arise in nature?
      • Prisoners dilemma’s with an unpredictably long future.
      • Non-zero sum games

Gene vs. body/survival machine:

  • Replicators came before us.
    • The things that survive or fail to survive is the replicators (genes), while we (the vehicles) are just temporary aggregations.
      • What makes for a good vehicle? (Survival machine)
        • All genes inside the vehicle must have the same outlet (Sperm/egg cells) into the future
          • Therefore individuals are better vehicles than groups of individuals.
    • Why did genes come together as organisms with the same outlet (Sperm/egg cells) into the future?
      • This question can be divided into 3:
        1. Why did genes go together in cells?
          • Genes instructs the coding of proteins like enzymes, and often more than one enzyme (made by different genes) need to be present to create a useful end product from a chemical.
        2. Why did cells go together into many celled bodies?
          • Bigger organisms can sometimes eat smaller ones.
          • The cells within the organism can specialize.
        3. Why do we start as single cells and reproduce in the form of single cells?
          • It allows for going back to the drawing board in each new generation.
          • The growth from a single cełl usually happens in a rigid manner, which is beneficial for creating complex tissues because it serves as a calendar?
          • The cells in the organism are more likely to be similar, and therefore more likely to cooperate.
    • Phenotype = The effect a gene has on its survival machine
      • Some genes are selected for their positive phenotypic effects
      • Other genes can be selected just because they are good to themselves
        • E.g. genes like segregation distorters cause themselves to be more than 50% likely to be chosen during meiotic division.
          • E.g. the T gene in mice is selected 95% of the time, and if a mice gets two, it dies.
    • Extended phenotype = The effect a gene has on the surrounding world (Including other survival machines)
      • Genes only directly affect protein synthesis, but protein synthesis can have a influence on x, which has an influence on y… and so on
        • Thereby genes can affect things like eye color, the survival of other animals or the chosen building materials for a house.
      • If some parasites genes success depends upon the survival/reproductive success of some other organism, and it exerts phenotypic effects upon it, then those effects are likely to evolve into being good for it.
        • Maybe the parasite and organism will evolve into one? Maybe that is how we evolved?
        • All of our genes success depends on the same outlet (Sperm/egg cells), and therefore they are also likely to work cooperate.

Accusations of genetic determinism

  • Genetic causes are in general no more deterministic than environmental causes
    • Genetic causes (and environmental causes) are only statistically more likely, other things being equal.
  • It’s even called genetically determined if the real cause was something in the environment.
    • E.g. if boys are taught to play with guns, then the genes that causes an individual to become a boy determines that he is more likely to play with guns.
    • All genes have their phenotypic effects in some environment
  • For most things there are many causes that can override each other
    • Some genes can override the effects of other genes
    • Some environmental causes can override genetic causes and vice verca.
    • E.g. Even when we get half of our genetic material from one of our parents, it will have different phenotypic effects depending on the other genes that are present, and the environment it finds itself in.

Is all behaviours perfect adaptions produced by natural selection?

  • Pan-adaptionism: The belief that all traits are perfect adaptions
  • Arguments against pan-adaptionism
    • Genes that are good in one embryological context might be bad genes in another
    • Time lag: Genes don’t always have time to evolve as fast as the environment
      • The genes of modern man were selected in an environment that is very different from the modern world we live in today
    • We can only change in small ways through mutations, and all intermediate configurations of us need to survive
      • Selection favors the local optima over something which could potentially become a global optima
        • Therefore some “relaxation” of selection can actually help reach global optima.
        • But evolution has no foresight and simple reaches for local optima.
    • The available genetic variation is limited.
    • Almost everything has trade-offs
      • E.g. larger brain = More calories
    • Natural selection at the gene level, might not directly correlate with producing an optimal organism
    • Environmental unpredictability
    • All survival machines compete

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