Experimental evidence for the selfish gene vs. the selfish individual

Experimental evidence for the selfish gene vs. the selfish individual

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In the Selfish Gene, Dawkins makes the argument that a better view of evolution (i.e. more in accordance with experiment) is obtained if you view the basic unit of evolution to be the gene rather than the group. Having read the book, I am convinced (inasmuch as a layperson can be convinced) that group selection comes up with incorrect predictions about evolution, so is a fallacious interpretation of evolution (is this a correct interpretation of the book and is this conclusion common opinion among biologists?).

I have heard that historically, his book was part of a backlash against the then prevalent viw of group selection.


However, is there an experimental way to prove whether the gene-selection or individual-selection interpretation of evolution is more correct?

I hope my question is not ill-defined whilst leaving 'unit of evolution' vaguely defined.

My understanding of this is that the complete reference for molecular centralized evolution is The Selfish Gene itself. I'm going to cite Alan Grafen's essay here, Richard Dawkins, proposes that the logical, fundamental unit of evolution is the replicator.

The replicator is the fundamental unit of reproduction - whether these replicators survive or do not defines the properties of the biological system they reside in. These words were chosen carefully because DNA sequences themselves are not replicators exactly - many individual copies make up the animals in a gene pool and the replication of one copy or another doesn't matter. The distinction between a physical strand of DNA and the replicator is the bulk of more than one of Dawkins book. It shows why the life of an individual means nothing to biology or evolution, how the boundaries of genes as transcriptional elements do not define the replicon (commonly misunderstood by molecular biologists). The replicon (a genetic unit of replication) manifests a behavior or phenotype in the organism that helps it reproduce and is reproduced. This can be cooperation with other members of your species or egg rolling or killing other sperm and is usually the result of many individual mRNA transcripts working in concert. A given gene as defined by mRNA transcription commonly participates in multiple replicon type behaviors.

But DNA is in the mind of the molecular biology camp highly intertwined as a replicator because it is the physical medium through which the replicator is passed from one generation to another. Without DNA, meiosis and the rest there are no replicons. The earliest replicators were possibly simple transcripts which self replicated and not much more, but over time they have become a network of intertwined molecules working in a system.

To my understanding this is axiom more than proof. It does not need to be proven because the physical transmission of DNA replication over time is the minimal necessary scenario to picture biology and evolution as we understand it. The selection amongst groups of genes or groups of cells or groups of individual multicellular animals seem unnecessary given the physical framework of DNA replication.

Certainly that these connections have been shown. The inspiration for The Selfish Gene is the confirmation of Robert Triver's Selfish Gene hypothesis with the discovery of t a terribly selfish gene which takes up the better part of chromosome in drosophila and increases its chances of showing up in the next generation by showing up in sperm more than half the time. There are lots of other examples in the Selfish Gene and the Extended Phenotype, which answers many of the common questions about this thesis. The literature since has been pretty productive. That being understood, its one thing to prove that something is true in biology, and another thing to prove that all other similar mechanisms are simply not true.

Yet even in Dawkins essays we see that the replicator is a bit of an abstraction some practically indefinable group of genes. Even as they each compete against each other, they create phenotypes collectively and the replicon becomes abstracted from the fundamental mechanism of replication. The most popular example of replication Dawkins creates - the meme - has no relationship to DNA at all - a sticky idea that spreads socially and replicates in the minds of individuals.

When we look at terribly complicated but obviously advantageous behaviors, the connection between the replicator and the competition of individual genes gets muddy. EO Wilson, having discovered pheromones and started ecology and sociobiology as disciplines still publishes group selection arguments. Having studied social behavior in insects over his career and co-authored one of the most complete compendiums on the subject, he has put forth consistant arguments since the 70s that group selection still has a place in evolution. Unlike others, Wilson has I think always kept the conversation scientific and isn't jumping off any ideological cliffs (though responses say differently, the whole conversation is still published).

I don't see how an unbiased forum can ignore the fact that the editors of Nature still call this an open discussion. Some may object, but calling the subject closed is overreaching I feel. There are others besides Wilson; I'm not familiar enough with the whole discussion to go into David Sloane Wilson and the rest, though they publish in reputable places.

I've started in this post since the question has been sitting around for a while. I expect others will post their corrections/objections/views - please do! Whenever group selection is mentioned it often happens that someone will pop up and say 'this is not appropriate for a scientific discussion of biology here' but never any justification of disqualifying questions - I think that's not really scientific. The fundamental attraction to academic thought to me is that minority voices that have legitimate observations are tolerated and often result in scientific revolutions, after which they are venerated for their persistence.

Here's a good place to tell us why some questions are beneath discussion in biology. I personally do not agree; even if a position is intertwined by politics and religion, its the scientific value that should be judged, not by the company it keeps - lest science become just another intolerant clot, not driven by logic, observation and facts. I ask you, why bother then?

Genes Are Selfish People Are Not

Jain sanyasinis, or female ascetics, hold their peacock-feather brooms over their heads to avoid the sun during a festival in India. Jain mendicants use such brooms to sweep the ground before sitting or lying down, so as not to harm any tiny living creatures.

The word “altruism” was coined by Auguste Comte, the 19th-century social philosopher and early founder of sociology. It derives, in turn, from the Latin alter, for “other.” Although most people are grateful that altruism exists, evolutionary biologists have historically had trouble with it—or rather, trouble explaining altruism’s widespread existence in the natural world. The problem is that natural selection is not conducive to benefiting “others.” After all, natural selection is quintessentially a selfish process, in which winning—or at least staying in the game longer than others—is the bottom line.

Evolution proceeds by the differential reproduction of genes, so the challenge is to explain the persistence of a trait that, by definition, leads to an increase in the success of another while not increasing the success of oneself. Selfishness should defeat altruism every time, at least at the gene level.

Some confusion arises because biologists do not define altruism by the intentional state of an actor—benevolent feelings are unnecessary—but rather, by its consequences: whether it enhances the fitness (reproductive success) of the beneficiary while reducing that of the altruist. As a result, we can speak quite seriously about possible altruism in lions, bees and even viruses.

For that reason, the best scientific explanation for altruism’s existence (and the one accepted by most evolutionary biologists) is that, at the most basic causative level, altruism isn’t really altruism at all, but rather selfishness. When bodies appear to be acting altruistically, what’s actually happening is that “selfish” genes within those seeming altruists are benefiting identical copies of themselves in other bodies, often genetic relatives. Other mechanisms have also been identified, including reciprocity, manipulation, reputation enhancement and, at least in theory, group benefit: Some have proposed, that the herd or colony (or as we might say, community) is the unit of natural selection, rather than the individual organism.

This last possibility, although accepted at times in the past, has been largely debunked, with the recognition that, in fact, genes are the entities that reproduce themselves and that persist over time. Moreover, altruism is necessarily overwhelmed by selfishness within a group. In order for natural selection to promote altruism, groups containing altruists would have to reproduce themselves so effectively as to outweigh the selection against altruism among the group’s individuals. It’s a mighty tall order.

1. Conceptual Framework for the Debate

Psychological egoism is a thesis about motivation, usually with a focus on the motivation of human (intentional) action. It is exemplified in the kinds of descriptions we sometimes give of people’s actions in terms of hidden, ulterior motives. A famous story involving Abraham Lincoln usefully illustrates this (see Rachels 2003, p. 69). Lincoln was allegedly arguing that we are all ultimately self-interested when he suddenly stopped to save a group of piglets from drowning. His interlocutor seized the moment, attempting to point out that Lincoln is a living counter-example to his own theory Lincoln seemed to be concerned with something other than what he took to be his own well-being. But Lincoln reportedly replied: “I should have had no peace of mind all day had I gone on and left that suffering old sow worrying over those pigs. I did it to get peace of mind, don’t you see?”

The psychological egoist holds that descriptions of our motivation, like Lincoln’s, apply to all of us in every instance. The story illustrates that there are many subtle moves for the defender of psychological egoism to make. So it is important to get a clear idea of the competing egoistic versus altruistic theories and of the terms of the debate between them.

A. The Bare Theses

Egoism is often contrasted with altruism. Although the egoism-altruism debate concerns the possibility of altruism in some sense, the ordinary term “altruism” may not track the issue that is of primary interest here. In at least one ordinary use of the term, for someone to act altruistically depends on her being motivated solely by a concern for the welfare of another, without any ulterior motive to simply benefit herself. Altruism here is a feature of the motivation that underlies the action (Sober & Wilson 1998, p. 199). (Another sense of “altruism”—often used in a fairly technical sense in biology—is merely behavioral see §4a.) To this extent, this ordinary notion of altruism is close to what is of philosophical interest. But there are differences. For instance, ordinarily we seem to only apply the term “altruism” to fairly atypical actions, such as those of great self-sacrifice or heroism. But the debate about psychological egoism concerns the motivations that underlie all of our actions (Nagel 1970/1978, p. 16, n. 1).

Regardless of ordinary terminology, the view philosophers label “psychological egoism” has certain key features. Developing a clear and precise account of the egoism-altruism debate is more difficult than it might seem at first. To make the task easier, we may begin with quite bare and schematic definitions of the positions in the debate (May 2011, p. 27 compare also Rosas 2002, p. 98):

  • Psychological Egoism: All of our ultimate desires are egoistic.
  • Psychological Altruism: Some of our ultimate desires are altruistic.

We will use the term “desire” here in a rather broad sense to simply mean a motivational mental state—what we might ordinarily call a “motive” or “reason” in at least one sense of those terms. But what is an “ultimate” desire, and when is it “altruistic” rather than “egoistic”? Answering these and related questions will provide the requisite framework for the debate.

B. Egoistic vs. Altruistic Desires

We can begin to add substance to our bare theses by characterizing what it is to have an altruistic versus an egoistic desire. As some philosophers have pointed out, the psychological egoist claims that all of one’s ultimate desires concern oneself in some sense. However, we must make clear that an egoistic desire exclusively concerns one’s own well-being, benefit, or welfare. A malevolent ultimate desire for the destruction of an enemy does not concern oneself, but it is hardly altruistic (Feinberg 1965/1999, §9, p. 497 Sober & Wilson 1998, p. 229).

Similarly, despite its common use in this context, the term “selfish” is not appropriate here either. The psychological egoist claims that we ultimately only care about (what we consider to be) our own welfare, but this needn’t always amount to selfishness. Consider an ultimate desire to take a nap that is well-deserved and won’t negatively affect anyone. While this concerns one’s own benefit, there is no sense in which it is selfish (Henson 1988, §7 Sober & Wilson 1998, p. 227). The term “self-interest” is more fitting.

With these points in mind, we can characterize egoistic and altruistic desires in the following way:

  • One’s desire is egoistic if (and only if) it concerns (what one perceives to be) the benefit of oneself and not anyone else.
  • One’s desire is altruistic if (and only if) it concerns (what one perceives to be) the benefit of at least someone other than oneself.

It’s important that the desire in some sense represents the person as oneself (or, as the case may be, as another). For example, suppose that John wants to help put out a fire in the hair of a man who appears to be in front of him, but he doesn’t know that he’s actually looking into a mirror, and it’s his own hair that’s ablaze. If John’s desire is ultimate and is simply to help the man with his hair in flames, then it is necessary to count his desire as concerning someone other than himself, even though he is in fact the man with his hair on fire (Oldenquist 1980, pp. 27-8 Sober & Wilson 1998, p. 214).

C. Ultimate/Intrinsic Desires

The reason for the focus on ultimate desires is that psychological egoists don’t deny that we often have desires that are altruistic. They do claim, however, that all such altruistic desires ultimately depend on an egoistic desire that is more basic. In other words, we have an ulterior motive when we help others—one that likely tends to fly below the radar of consciousness or introspection.

Thus, we must draw a common philosophical distinction between desires that are for a means to an end and desires for an end in itself. Instrumental desires are those desires one has for something as a means for something else ultimate desires are those desires one has for something as an end in itself, not as a means to something else (see Sober & Wilson 1998, pp. 217-222). The former are often called “extrinsic desires” and the latter “intrinsic desires” (see e.g. Mele 2003 Ch. 1.8.). Desires for pleasure and the avoidance of pain are paradigmatic ultimate desires, since people often desire these as ends in themselves, not as a mere means to anything else. But the class of ultimate desires may include much more than this.

D. Relating Egoism and Altruism

There are two important aspects to highlight regarding how psychological egoism and altruism relate to one another. First, psychological egoism makes a stronger, universal claim that all of our ultimate desires are egoistic, while psychological altruism merely makes the weaker claim that some of our ultimate desires are altruistic. Thus, the former is a monistic thesis, while the latter is a pluralistic thesis (Sober & Wilson 1998, p. 228). Consequently, psychological egoism is easier to refute than the opposing view. If one were to successfully demonstrate that some—even just one—of a person’s ultimate desires are altruistic, then we can safely reject psychological egoism. For example, if Thomas removes his heel from another’s gouty toe because he has an ultimate desire that the person benefit from it, then psychological egoism is false.

Second, the positions in the debate are not exactly the denial of one another, provided there are desires that are neither altruistic nor egoistic (Stich, Doris, & Roedder 2010, sect. 2). To take an example from Bernard Williams, a “madman” might have an ultimate desire for “a chimpanzees’ tea party to be held in the cathedral” (1973, p. 263). He does not desire this as a means to some other end, such as enjoyment at the sight of such a spectacle (he might, for example, secure this in his will for after his death). Assuming the desire for such a tea party is neither altruistic nor egoistic (because it doesn’t have to do with anyone’s well-being), would it settle the egoism-altruism debate? Not entirely. It would show that psychological egoism is false, since it would demonstrate that some of our ultimate desires are not egoistic. However, it would not show that psychological altruism is true, since it does not show that some of our ultimate desires are altruistic. Likewise, suppose that psychological altruism is false because none of our ultimate desires concern the benefit of others. If that is true, psychological egoism is not thereby true. It too could be false if we sometimes have ultimate desires that are not egoistic, like the madman’s. The point is that the theses are contraries: they cannot both be true, but they can both be false.

Unravelling the genetics of fungal fratricide

Selfish genes are genes that are passed on to the next generation but confer no advantage on the individual as a whole, and may sometimes be harmful. Researchers at Uppsala University have, for the first time, sequenced (or charted) two selfish genes in the fungus Neurospora intermedia that cause fungal spores to kill their siblings. Unexpectedly, the genes were not related to each other, perhaps indicating that selfish genes are more common than previously thought.

One mainstay of evolutionary theory is survival of the fittest individuals, whose genes can thereby be passed on. However, one type of gene -- 'selfish' genes -- can be passed on without benefiting the individual. Biologists believe that selfish genes may be important drivers of evolution, and it is therefore essential to understand how selfish genes function in order to understand more general evolutionary patterns.

One example of a selfish gene, known as the 'spore killer', has been found in certain fungi. If a fungal spore carries this gene, the spore kills all related ('sibling') spores that lack the gene. The spore-killing gene will thus be passed on, despite being detrimental to the fungus as a whole. Similar genes for killing siblings have been found in other organisms, such as fruit flies and mice, but in those species it is a matter of sperm that destroy sibling sperm. Selfish genes may also serve as pesticides: inserting selfish genes into malaria-bearing mosquitoes can cause individuals of one sex only to be born, thereby reducing their population size. However, knowledge of how selfish genes function genetically, and of how they spread in nature, is still limited.

For the first time, a research group at Uppsala University's Department of Systematic Biology has succeeded in sequencing complete genomes that contain complex selfish genes. The researchers sequenced genomes from two different types of spore killer found in the ascomycete fungus Neurospora intermedia. The results have now been published in Nature Communications.

"Sequencing selfish genes of this type is difficult, since they are often located on parts of the chromosome that have accumulated a huge amount of mutations, and where pieces of the chromosome have been rearranged," says Hanna Johannesson, who headed the study.

Sequencing of the genome showed that the spore-killing genes exist in chromosome regions where much of the chromosome has changed direction: forming so called 'inversions'. These chromosome regions have also collected numerous new mutations and regions where repetitive DNA has expanded. The mutations may mean that individuals with spore-killing genes are more poorly adapted, and they may be an explanation of why these spore-killing genes are unusual in Neurospora intermedia.

"One result that surprised us was that the two spore killers were not related to each other, and use different genes to kill sibling spores. This may suggest that selfish genes in general, and spore-killing genes in particular, are more common than people used to think," says Jesper Svedberg, the main author of the study.


Rapidly growing evidence emerging from genomics and advances in genetics indicate that SGEs are important motors for evolutionary change and innovation. Several general principles have reoccurred in the discussion above, and I will briefly revisit these themes here. The first is that SGEs lead to antagonistic coevolution with other components of the genome. Important features of eukaryotic genomes (e.g., DNA methylation, RNAi, small RNA regulatory pathways, R-M systems) have evolved, at least in part, as defense mechanisms against SGEs. Many genetic elements have mixed phenotypes, with both selfish (parasitic) and “beneficial” (“mutualistic”) features. The classic example is the mitochondrion, which is clearly beneficial but also shows selfish features (e.g., cytoplasmic male sterility) that reduce nuclear gene fitness, thus leading to genetic conflict. Evolutionary dependency can also evolve in hosts with ubiquitous SGEs, which can lead to irreversible dependence. Growing evidence supports a significant role of SGEs in eukaryotic development and speciation, and possibly also in extinction of species. Genome domestication of SGEs leads to evolutionary innovations, including acquisition of new genes and gene regulation from TEs, heritable microbes (e.g., Wolbachia), and selfish plasmids. Safe havens can promote longer associations of SGEs with host lineages and also may facilitate their domestication. Finally, distinctions are made between the evolutionary consequences of SGEs and the factors that maintain them over evolutionary time. Clear formulations of the idea of evolvability as a means for evolutionary maintenance of SGEs will facilitate rigorous testing of this idea. Nevertheless, current evidence strongly supports the view that SGEs are maintained by their transmission-enhancing phenotypes and that evolutionary innovations emerging from them are a consequence of their existence rather than the cause.

Summary and future prospects

The selfish nature of SGEs generates conflict with the rest of the genome that will select for suppression and silencing of selfishness. This is especially true for SGEs causing sex ratio distortion that in turn can promote the evolution of new sex chromosomes. However, changes to sex determination, such as going from male heterogamety to female heterogamety or vice versa, will alter the opportunity for selection. Heterogamety exposes recessive alleles to selection and therefore generates differential selection on sex-linked genes expressed in males and females (Rice, 1984 ). In principle, any SGE that is already present on a sex chromosome (or on a former autosome now involved in sex determination) will experience a shift in the strength of sex-specific selection. And as mentioned, segregation distorters such as sex-linked meiotic drivers are themselves magnets for SA alleles and hence are expected to accumulate on the driving sex chromosome (Rydzewski et al., 2016 ). Many SGEs associated with sex ratio bias may therefore have dramatically different fitness effects when expressed in males or females following a shift in sex determination, depending on the population sex ratio and the degree of sex bias. For example, a genome that has experienced extensive periods of feminizing selection (e.g. by feminizing, male-killing or parthenogenesis-inducing bacteria) may have accumulated female-benefit alleles that lower male fitness when expressed in ‘rescued’ males after the evolution of suppressors of sex ratio distortion. We may predict that over time the cost of expressing such newly exposed SA alleles in the ‘rescued’ sex should be ameliorated (Bonduriansky & Chenoweth, 2009 ). The resurgence of SA alleles may therefore be more prominent in populations experiencing a recent spread of a segregation-distorting suppressor allele or a shift in sex determination. In general, the rapid turnover of sex chromosomes generated by sex ratio distorters will alter the exposure of sex-linked SA alleles to selection and contribute to sexual conflict. Seeing that sex chromosomes are magnets for SGEs and SA alleles, and in turn SGEs promote sex chromosome turnover, there is a direct link between the recurrent intragenomic conflict caused by SGEs and the resurgence and exposure of SA alleles on sex chromosomes.

Selfish genetic elements may also represent an overlooked source generating balancing selection. Theory shows that because of the predicted tight linkage that is expected to accumulate between segregation distorters and SA alleles, they will contribute to increased polymorphism at driving and SA loci and thus maintain overall genetic variation (Patten, 2014 ). However, also non-driving SGEs have the potential to maintain genetic variation in sexually selected traits by generating strong opposing selection. For example, feminizing endosymbionts have the potential to expose male genomes to extensive feminizing selection that could compromise trait expression when males eventually escape feminization through naturally occurring curing events. As yet, there is no definitive verification of this suggestion although preliminary findings indicate that male ultra-violet wing coloration – a sexually selected trait in male Eurema hecabe butterflies – is eroded when exposed to feminizing selection caused by a maternally inherited female-biasing agent (Wedell & Kemp, unpubl.). Future work will reveal to what extent this reduction in male trait value is directly due to feminizing selection imposed by the endosymbiont and therefore raises the possibility it may balance the increased trait value favoured by female choice (Kemp, 2008 ).

In this review, I have outlined several ways in which SGEs can directly shape sexual selection and sexual conflict by promoting sex chromosome evolution (e.g. sex ratio distorters), affecting gene expression of sex-linked genes with SA effects (e.g. TEs), generating strong sex-specific selection (e.g. maternally transmitted endosymbionts and mitochondria) and acting as a magnet for SA alleles (e.g. segregation distorters). It is likely that there are many more undetected cases of SGEs with the potential to generate sexual selection and sexual conflict, but that have largely gone undetected (Lindholm et al., 2016 ). Genetic conflict that involves antagonistic co-evolution of SGEs and suppressors is often only uncovered in interpopulation crosses. Seeing the prevalence of SGEs in nature, this source of sexual conflict is likely to be greatly overlooked.

Innate Behaviors: Movement and Migration

Innate or instinctual behaviors rely on response to stimuli. The simplest example of this is a reflex action, an involuntary and rapid response to stimulus. To test the “knee-jerk” reflex, a doctor taps the patellar tendon below the kneecap with a rubber hammer. The stimulation of the nerves there leads to the reflex of extending the leg at the knee. This is similar to the reaction of someone who touches a hot stove and instinctually pulls his or her hand away. Even humans, with our great capacity to learn, still exhibit a variety of innate behaviors.

Kinesis and Taxis

Another activity or movement of innate behavior is kinesis, or the undirected movement in response to a stimulus. Orthokinesis is the increased or decreased speed of movement of an organism in response to a stimulus. Woodlice, for example, increase their speed of movement when exposed to high or low temperatures. This movement, although random, increases the probability that the insect spends less time in the unfavorable environment. Another example is klinokinesis, an increase in turning behaviors. It is exhibited by bacteria such as E. coli which, in association with orthokinesis, helps the organisms randomly find a more hospitable environment.

A similar, but more directed version of kinesis is taxis: the directed movement towards or away from a stimulus. This movement can be in response to light (phototaxis), chemical signals (chemotaxis), or gravity (geotaxis) and can be directed toward (positive) or away (negative) from the source of the stimulus. An example of a positive chemotaxis is exhibited by the unicellular protozoan Tetrahymena thermophila. This organism swims using its cilia, at times moving in a straight line, and at other times making turns. The attracting chemotactic agent alters the frequency of turning as the organism moves directly toward the source, following the increasing concentration gradient.

Fixed Action Patterns

A fixed action pattern is a series of movements elicited by a stimulus such that even when the stimulus is removed, the pattern goes on to completion. An example of such a behavior occurs in the three-spined stickleback, a small freshwater fish (Figure 1). Males of this species develop a red belly during breeding season and show instinctual aggressiveness to other males during this time. In laboratory experiments, researchers exposed such fish to objects that in no way resemble a fish in their shape, but which were painted red on their lower halves. The male sticklebacks responded aggressively to the objects just as if they were real male sticklebacks.

Figure 1. Male three-spined stickleback fish exhibit a fixed action pattern. During mating season, the males, which develop a bright red belly, react strongly to red-bottomed objects that in no way resemble fish.


Figure 2. Wildebeests migrate in a clockwise fashion over 1800 miles each year in search of rain-ripened grass. (credit: Eric Inafuku)

Migration is the long-range seasonal movement of animals. It is an evolved, adapted response to variation in resource availability, and it is a common phenomenon found in all major groups of animals. Birds fly south for the winter to get to warmer climates with sufficient food, and salmon migrate to their spawning grounds. The popular 2005 documentary March of the Penguins followed the 62-mile migration of emperor penguins through Antarctica to bring food back to their breeding site and to their young. Wildebeests (Figure 2) migrate over 1800 miles each year in search of new grasslands.

Although migration is thought of as innate behavior, only some migrating species always migrate (obligate migration). Animals that exhibit facultative migration can choose to migrate or not. Additionally, in some animals, only a portion of the population migrates, whereas the rest does not migrate (incomplete migration). For example, owls that live in the tundra may migrate in years when their food source, small rodents, is relatively scarce, but not migrate during the years when rodents are plentiful.


Figure 3. The painted stork uses its long beak to forage. (credit: J.M. Garg)

Foraging is the act of searching for and exploiting food resources. Feeding behaviors that maximize energy gain and minimize energy expenditure are called optimal foraging behaviors, and these are favored by natural section. The painted stork, for example, uses its long beak to search the bottom of a freshwater marshland for crabs and other food (Figure 3).

Is the Selfish Gene Theory True?

The selfish gene theory has truth to it, but it is ultimately misleading. [5]

We are born selfish in some ways, but ultimately it is selfishness on behalf of the species (not the individual). This could just as easily be described as being genetically “selfless” (the selfless gene). The fact is, humans are cooperative by nature, just like all life, and sometimes cooperation manifests as competition.

It’s probably more accurate to simply say, humans are complex and have both selfish and selfless traits. We are hardwired for cooperation and competition, we are hardwired to be selfish and compassionate, but all of this is simply in the interest of our genes. Beyond this, it’s simply a matter of nurture.

Do we teach others to have a small in-group, or do we teach them to extend compassion? There has historically been, unsurprisingly, two schools of thought. With that in mind, here is Richard Dawkins explaining his take on “the selfish gene”.

We come hardwired to be both “selfish” and “compassionate”, beyond this nurture plays a big role.

Don’t forget, if you are old enough to read this article, you are old enough to nurture yourself and define your “in-group” as humanity and you’re old enough to realize that the “out-group” can be in.

Genomic Imprinting

The discovery that hereditary information can be silent in some generations and expressed in others dates back to the classic experiments of Mendel on dominant and recessive alleles. But in the 1980s a new form of silent allele was discovered: genomic imprinting. Experiments with mice and corn demonstrated that the expression of some genes depended not on their dominant/recessive interaction but instead on their parent of origin (reviewed in Reik and Walter 2001). This early work was followed by a succession of experiments that revealed the molecular processes underlying genomic imprinting (reviewed in Köhler et al. 2012 Hackett and Surani 2013). These experiments led to a mechanistic understanding of genomic imprinting but told us nothing about its functional underpinning i.e., what purpose did imprinting achieve and why did imprinting evolve? In a series of synthesis articles written by David Haig and his collaborators (Haig and Westoby 1989, 1991 Haig and Graham 1991 Moore and Haig 1991 Haig 1993), a convincing case was made that genomic imprinting evolved in large part due to a tug-of-war between paternal and maternal genes in offspring influencing the level of maternal investment that they receive, and 20 years of subsequent studies strongly support this conclusion (Brandvain et al. 2011). In the case of genomic imprinting, its discovery and advances in underlying its molecular mechanisms were accomplished via the paradigm of experimentation in model systems, but an understanding of the functional significance of imprinting was achieved via the synthesis paradigm.

Why Did Witch Hunts Go Viral?

If it is in fact accurate to think of witch trial beliefs as viruses, maybe it would be helpful to study their spread the way scientists study the spread of viruses: using an epidemiological model. “The Witch, No. 1” (1892) by Joseph E. Baker / Wikicommons

I t’s hard to make sense of witch hunts. Many people of early modern Europe and colonial America seemed to have genuinely believed that witches posed a serious threat. But if witch trials—like the ones in Salem, Massachusetts, and in European communities between the 1400s and 1700s—escalated out of control, with no clear beneficiaries, then why did they happen? In a new paper, philosopher Maarten Boudry and historian Steije Hofhuis argue that witch hunts weren’t “coordinated intelligent strategies with underlying goals,” even though it often looks like they were. In other words, they weren’t motivated by a desire to, for example, oppress the lower classes or women, and weren’t a result of powerful economic interests.

One reason they find those theories unconvincing is that there appears to be no evidence in historical documents of anyone explicitly organizing against particular groups. It is, Boudry and Hofhuis write, “hard to grasp how the witch-hunters could have developed such a shrewd hidden functional purpose, if they did not discuss this with each other.” Instead they offer a Darwinian explanation for witch hunts, involving selfish memes. Put simply, the idea of witches propagated because it was good at propagating, even though no individual really wanted it to. “We argue,” they write, “that witch persecutions form a prime example of a ‘viral’ socio-cultural phenomenon that reproduces ‘selfishly,’ even harming the interests of its human hosts.” Although I’m skeptical, the theory is fascinating and is worth thinking about.

The self-reinforcing character of witch-hunting practices does not, in itself, demand memes.

The idea of selfish memes originates from evolutionary biologist Richard Dawkins. In his view, famously expounded in The Selfish Gene, genes are “selfish” because replicating takes top priority—genes are “interested” in their own fitness. This supersedes its other effects: To replicate might come at some cost to the organism a gene is in, and yet it persists. Dawkins thought the same principle was at work in cultural evolution. He proposed that bits of culture—various beliefs and behaviors—should be thought of as variants in the same way that there are different variants of the same gene across human populations.

His idea is controversial. What usually concerns critics of meme theory is its usefulness: the degree to which it captures cultural phenomena and explains their emergence. It has been criticized, for instance, for not being of much help in understanding history. But Boudry and Hofhuis disagree, and argue that witch hunts are the sort of historical event for which meme theory does provide some explanatory value.

Many beliefs about witches and practices in witch trials were self-reinforcing—trying and convicting one person for witchcraft often led to trying many more. For example, evidence for being a witch included naming other witches, and accused witches were frequently interrogated by torture. Unsurprisingly, then, successful witch trials often resulted in many more witch trials, and so on. Boudry and Hofhuis propose that selfish memes help to explain the emergence of these witch hunts: Witch hunts escalated because the memes associated with them were selfish. “The evolutionary scenario that we propose is as follows,” Boudry and Hofhuis write, “Ideas that accidentally triggered larger persecutions were cumulatively preserved precisely because of that effect, in repeated rounds of variation and selection.” Witch memes arose by accident in a normal process of cultural variation, and they stuck because they are good at reproducing themselves.

Convinced? Not me. The self-reinforcing character of witch-hunting practices does not, in itself, demand memes. Boudry and Hofhuis note the self-reinforcing character before they even get to talking about memes: “Witchcraft therefore became known as a crimen exceptum an extraordinary crime requiring extraordinary means of investigation… Various forms of physical torment were recommended to make alleged witches confess to their evil deeds and to make them name accomplices. Unsurprisingly, the likelihood of suspects pleading guilty significantly increased.” When they draw these connections between some aspects of witch hunts and selfish memes, what we are left with is basically an analogy—a Darwinian vocabulary for saying that those beliefs and practices are self-reinforcing.

To call a belief a metaphorically selfish meme is just to restate its property of self-reinforcement: They are selfish because they are self-reinforcing they are self-reinforcing because they are selfish. So, while the analogy is not necessarily wrong or inaccurate, selfish meme vocabulary does not help researchers understand or explain witch hunts in any greater depth.

W hat does explain them, then? Perhaps conformity bias. It is worth considering that maybe only a few people genuinely believed witches were among them, and that apparent beliefs about witches might have spread, contrary to the selfish-meme view, by no inherent property of their own, but by other mechanisms of social influence. Witch panics are popularly called instances of mass hysteria—and one way that scientists make that idea more precise is to compare them to psychological experiments on how people conform to groups. In the 1950s, the psychologist Solomon Asch showed evidence of a conformity bias in his subjects. In one of his most famous experiments, he asked subjects to match the length of a vertical line with one of three others—one option was in fact the same length, while the others varied. Seven actors posing as fellow subjects coordinated to deliberately select a line that did not match. One-third of experimental subjects went along with the majority, and reported that those lines matched, even though they clearly did not. Conformity bias separates behavior from belief: People can act in accordance with beliefs they do not truly hold, as a consequence of context.

While many people at the time probably believed in the existence and dangers of witchcraft, the explanation by conformity bias would only require a few to believe in the presence of witches in their own community, and in the legitimacy of the methods used to interrogate and convict them. Then, the beliefs would appear to spread, but not because the beliefs themselves have some property of selfishness—simply because the beliefs appear to be held by others. Conformity bias may not be a complete explanation for witch hunts, but it could be a powerful factor, especially considering that the majority of people, in the case of witch hunts, were not strangers to each other, as in Asch’s experiments they were known and presumably trusted members of the community.

Another possible explanation builds off of Boudry and Hofhuis’ framework: They briefly discuss the idea that memes can be compared to viruses—replicating themselves using humans at their expense—and that this comparison might be more than just a metaphor. “The similarities between biological viruses and outbreaks of witch panics are not just superficial or curious coincidences without any theoretical significance,” they write. “On the contrary, the analogy arises from the fact that both phenomena underwent Darwinian selection processes.”

If it is in fact accurate to think of witch trial beliefs as viruses, maybe it would be helpful to study their spread the way scientists study the spread of viruses: using an epidemiological model. This would take into account that the witchcraft beliefs are “encouraging” their own persistence and would yield a pattern for how they might spread. This incorporates logic of natural selection that Boudry and Hofhuis stress in their selfish meme framework, but it goes a step further by allowing researchers to obtain more specific patterns for the spread of ideas.

Several studies have shown that fairly basic epidemiological models can model the spread of ideas. Researchers begin with an established mathematical model for the spread of disease and carefully adapt the variables to instead represent the spread of ideas. Some researchers take Dawkins’ memes as a starting point, but it is worth pointing out that they’re not necessary: If “selfishness” is meant to describe how easily an idea spreads, researchers can capture that with a variable called the “incidence rate”—the number of new “cases” of the idea divided by the “susceptible” population for some interval of time. Viruses that are exceptionally good at rapidly reproducing themselves and getting out to other hosts have a higher incidence rate. If they are genuine beliefs, the spread of beliefs about witchcraft can be at least partially explained by epidemiological models, which, like meme theory, rely on replication and transmission. But they don’t actually make use of the meme framework itself.

Neither of these alternative explanations entirely solves the puzzle of witch hunts, either. If conformity bias is responsible, it is still unclear why those apparent beliefs in particular were so ripe for spreading. If epidemiological modeling is the correct approach, then the causes for high incidence rates are still hazy. What makes these ideas different from other self-reinforcing ones—or why the cycle of self-reinforcement is so hard to break—is not totally obvious from any of these possible explanations.