‘The Selfish Gene’, by Richard Dawkins, Oxford University Press, 1976.

Selfish Genes ≠ Selfish Phenotypes

Richard Dawkins’s ‘The Selfish Gene’ is among the most celebrated, but also the most misunderstood, works of popular science.

Thus, among people who have never read the book (and, strangely, a few who apparently have) Dawkins is widely credited with arguing that humans are inherently selfish, that this disposition is innate and inevitable, and even, in some versions, that behaving selfishly is somehow justified by our biological programming, the titular ‘Selfish Gene’ being widely misinterpreted as referring to a gene that causes us to behave selfishly.

Actually, Dawkins is not concerned, either directly or primarily, with humans at all.

Indeed, he professes to be “not really very directly interesting in man”, whom he dismisses as “a rather aberrant species” and hence peripheral to his own interest, namely how evolution has shaped the bodies and especially the behaviour of organisms in general (Dawkins 1981: p556).

‘The Selfish Gene’ is then, unusually, if not uniquely, for a bestselling work of popular science, a work, not of human biology nor even of non-human zoology, ethology or natural history, but rather of theoretical biology.

Moreover, in referring to genes as ‘selfish’, Dawkins has in mind not a trait that genes encode in the organisms they create, but rather a trait of the genes themselves.

In other words, individual genes are themselves conceived of as ‘selfish’ (in a metaphoric sense), in so far as they have evolved by natural selection to selfishly promote their own survival and replication by creating organisms designed to achieve this end.

Indeed, ironically, as Dawkins is at pains to emphasise, selfishness at the genetic level can actually result in altruism at the level of the organism or phenotype.

This is because, where altruism is directed towards biological kin, such altruism can facilitate the replication of genes shared among relatives by virtue of their common descent. This is referred to as kin selection or inclusive fitness theory and is one of the central themes of Dawkins’ book.

Yet, despite this, Dawkins still seems to see organisms themselves, humans very much included, as fundamentally selfish – albeit a selfishness tempered by a large dose of nepotism.

Thus, in his opening paragraphs no less, he cautions:

“If you wish, as I do, to build a society in which individuals cooperate generously and unselfishly towards a common good, you can expect little help from our biological nature. Let us try to teach generosity and altruism, because we are born selfish” (p3).

The Various Editions

In later editions of his book, namely those published since 1989, Dawkins tempers this rather cynical view of human and animal behaviour by the addition of a new chapter – Chapter 12, titled ‘Nice Guys Finish First’.

This new chapter deals with the subject of reciprocal altruism, a topic he had actually already discussed earlier, together with the related, but distinct, phenomenon of mutualism,^[1] in Chapter 10 (entitled, ‘You Scratch My Back, I’ll Ride on Yours’).

In this additional chapter, he essentially summarizes the work of political scientist Robert Axelrod, as discussed in Axelrod’s own book The Evolution of Co-Operation. This deals with evolutionary game theory, specifically the iterated prisoner’s dilemma, and the circumstances in which a cooperative  strategy can, by cooperating only with those who have a history of reciprocating, survive, prosper, evolve, and, in the long-term, ultimately outcompete  and hence displace those strategies which maximize only short-term self-interest.

Post-1989 editions also include another new chapter titled ‘The Long Reach of the Gene’ (Chapter 13).

If, in Chapter 12, the first additional chapter, Dawkins essentially summarised the contents of of Axelrod’s book, The Evolution of Cooperation, then, in Chapter 13, he summarizes his own book, The Extended Phenotype.

In addition to these two additional whole chapters, Dawkins also added extensive endnotes to these post-1989 editions.

These endnotes clarify various misunderstandings which arose from how he explained himself in the original version, defend Dawkins against some criticisms levelled at certain passages of the book and also explain how the science progressed in the years since the first publication of the book, including identifying things he and other biologists got wrong.

With still more recent new editions, the content of ‘The Selfish Gene’ has burgeoned still further. Thus, he 30th Anniversary Edition boasts only a new introduction; the recent 40th Anniversary Edition, published in 2016, boasts a new Epilogue too. Meanwhile, the latest so-called Extended Selfish Gene boasts, in addition to this, two whole new chapters.

Actually, these two new chapters are not all that new, being lifted wholesale from, once again, The Extended Phenotype, a work whose contents Dawkins has already, as we have seen, summarized in Chapter 13 (‘The Long Reach of the Gene’), itself an earlier addition to the book’s seemingly ever expanding contents list.

The decision not to entirely rewrite ‘The Selfish Gene’ was apparently that of Dawkins’ publisher, Oxford University Press.

This was probably the right decision. After all, ‘The Selfish Gene’ is not a mere undergraduate textbook, in need of revision every few years in order to keep up-to-date with the latest published research.

Rather, it was a landmark work of popular science, and indeed of theoretical biology, that introduced a new approach to understanding the evolution of behaviour and physiology to a wider readership, composed of biologist and non-biologist alike, and deserves to stand in its original form as a landmark in the history of science.

However, while the new introductions and the new epilogue is standard fare when republishing a classic work several years after first publication, the addition of four (or two, depending on the edition) whole new chapters strikes me less readily defensible.

For one thing, they distort the structure of the book, and, though interesting in and of themselves, always read for me rather as if they have been tagged on at the end as an afterthought – as indeed they have.

The book certainly reads best, in a purely literary sense, in its original form (i.e. pre-1989 editions), where Dawkins concludes with an optimistic, if fallacious, literary flourish (see below).

Moreover, these additional chapters reek of a shameless marketing strategy, designed to deceive new readers into paying the full asking price for a new edition, rather than buying a cheaper second-hand copy or just keeping their old one.

This is especially blatant in respect of the book’s latest incarnation, The Extended Selfish Gene, which, according to the information provided on Oxford University Press’s own website, was released only three months after the previous 40th Anniversary Edition, yet includes two additional chapters.

One frankly expects better from so presigious a publisher such as Oxford University Press, and indeed so celebrated a biologist and science writer as Richard Dawkins, especially as I suspect neither are especially short of money.

If I were recommending someone who has never read the book before on which edition to buy, I would probably advise them to get a second-hand copy of any post-1989 editions, since these can now be picked up very cheap, and include the additional endnotes which I personally often found very interesting.

On the other hand, if you want to read three additional chapters either from or about The Extended Phenotype then you are probably best to buy, instead, well… The Extended Phenotype – as this is also now a rather old book of which, as with ‘The Selfish Gene’, old copies can now be picked up very cheap.

The ‘Gene’s-Eye-View’ of Evolution

The Selfish Gene is a seminal work in the history of biology primarily because Dawkins takes the so-called ‘gene’s-eye-view’ of evolution to its logical conclusion. To this extent, contrary to popular opinion, Dawkins’ exposition is not merely a popularization, but actually breaks new ground theoretically.

Thus, John Maynard Smith famously talked of ‘kin selection’ by analogy with ‘group selection’ (Smith 1964). However, William Hamilton, who formulated the theory underlying these concepts, always disliked the term ‘kin selection’ and talked instead of the ‘direct’, ‘indirect’ and ‘inclusive fitness’ of organisms (Hamilton 1964a; 1964b).

However, Dawkins takes this line of thinking to its logical conclusion by looking – not at the fitness or reproductive success of organisms or phenotypes – but rather at the success in self-replication of genes themselves.

Thus, although he certainly stridently rejects group-selection, Dawkins replaces this, not with the familiar individual-level selection of classical Darwinism, but rather with a new focus on selection at the level of the gene itself.

Abstract Animals?

Much of the interest, and no little of the controversy, arising from ‘The Selfish Gene’ concerned, of course, the potential application of its theory to humans. However, in the book itself, humans, whom, as mentioned above, Dawkins dismisses as a “rather aberrant species” in which he professes to be “not really very directly interested” (Dawkins 1981: p556) are actually mentioned only occasionally and briefly.

Indeed, most of the discussion is purely theoretical. Even the behaviour of non-human animals is described only for illustrative purposes, and even these illustrative examples often involve simplified hypothetical creatures rather than descriptions of the behaviour of real organisms.

For example, he illustrates his discussion of the relative pros and cons of either fighting or submitting in conflicts over access to resources by reference to ‘hawks’ and ‘doves’ – but is quick to acknowledge that these are hypothetical and metaphoric creatures, with no connection to the actual bird species after whom they are named:

“The names refer to conventional human usage and have no connection with the habits of the birds from whom the names are derived: doves are in fact rather aggressive birds” (p70).

Indeed, even Dawkins’ titular “selfish genes” are rather abstract and theoretical entities. Certainly, the actual chemical composition and structure of DNA is of only peripheral interest to him.

Indeed, often he talks of “replicators” rather than “genes” and is at pains to point out that selection can occur in respect of any entity capable of replication and mutation, not just DNA or RNA. (Hence his introduction of the concept of memes: see below).

Moreover, Dawkins uses the word ‘gene’ in a somewhat different sense to the way the word is employed by most other biologists. Thus, following George C. Williams in Adaptation and Natural Selection, he defines a “gene” as:

“Any portion of chromosomal material that potentially lasts for enough generations to serve as a unit of natural selection” (p28).

This, of course, makes his claim that genes are the principle unit of selection something approaching a tautology or circular argument.

Sexual Selection in Humans?

Where Dawkins does mention humans, it is often to point out the extent to which this “rather aberrant species” apparently conspicuously fails to conform to the predictions of selfish-gene theory.

For example, at the end of his chapter on sexual selection (Chapter 9, titled, “Battle of the Sexes”) he observes that, in contrast to most other species, among humans, at least in the West, it seems to be females who are most active in using physical appearance as a means of attracting mates:

“One feature of our own society that seems decidedly anomalous is the matter of sexual advertisement… It is strongly to be expected on evolutionary grounds that where the sexes differ, it should be the males that advertise and the females that are drab… [Yet] there can be no doubt that in our society the equivalent of the peacock’s tail is exhibited by the female, not the male” (p164).

Thus, among most other species, it is males who have evolved more elaborate plumages and other flashy, sexually selected ornaments. In contrast, females of the same species are often comparatively drab in appearance.

Yet, in modern western societies, Dawkins observes, it is more typically women who “paint their faces and glue on false eyelashes” (p164).

Here, it is notable that Dawkins, being neither an historian nor an anthropologist, is careful to restricts his comments to “our own society” and, elsewhere, to “modern western man”.

Thus, one explanation is that it is only our own ‘WEIRD’, western societies that are anomalous?

Thus, Matt Ridley, in The Red Queen, proposes that maybe:

“Modern western societies have been in a two-century aberration from which they are just emerging. In Regency England, Louis XIV’s France, medieval Christendom, ancient Greece, or among the Yanomamö, men followed fashion as avidly as women. Men wore bright colours, flowing robes, jewels, rich materials, gorgeous uniforms, and gleaming, decorated armour. The damsels that knights rescued were no more fashionably accoutred than their paramours. Only in Victorian times did the deadly uniformity of the black frock coat and its dismal modern descendant, the grey suit, infect the male sex, and only in this century have women’s hemlines gone up and down like yo-yos” (The Red Queen: p292).

There is an element of truth here. Indeed, the claim is corroborated by Darwin, who observed in The Descent of Man:

“In most, but not all parts of the world, the men are more highly ornamented than the women, and often in a different manner; sometimes, though rarely, the women are hardly ornamented at all” (The Descent of Man).

However, I suspect Ridley’s observation partly reflects a misunderstanding of the different purposes for which men and women use clothing, including bright and elaborate clothing.

Indeed, it rather reminds me of Margaret Mead’s claim that, among the Tschambuli of Papua New Guinea, sex-roles were reversed because, here, she reported, it was men who painted their faces and wore ‘make-up’, not women.

Yet what Mead neglected to mention, or perhaps failed to understand, was that the ‘make-up’ and face-paint that she evidently found so effeminate was actually war-paint that a Tschambuli warrior was only permitted to wear after killing his first enemy warrior, an obviously very male activity (see Homicide: Foundations of Human Behavior: p152).

Darwin himself, incidentally, although alluding to the “highly orgnamented” appearance of men of many cultures in the passage from The Descent of Man quoted above, well understood the different purposes of male and female ornamentation, writing in this same work:

“Women are everywhere conscious of the value of their own beauty; and when they have the means, they take more delight in decorating themselves with all sorts of ornaments than do men” (The Descent of Man).

Of course, clothes and makeup are an aspect of behaviour rather than morphology, and thus more directly analogous to, say, the nests (or, more precisely, the bowers) created by male bowerbirds than the tail of the peacock.

However, behaviour is, in principle, no less subject to natural selection (and sexual selection) than is morphology, and therefore the paradox remains.

Moreover, even concentrating our focus exclusively on morphology, the sex difference still seems to remain.

Thus, perhaps the closest thing to a ‘peacock’s tail’ in humans (i.e. a morphological trait designed to attract mates) is a female trait, namely breasts.

Thus, as Desmond Morris first observed, in humans, the female breasts seem to have been co-opted for a role in sexual selection, since, unlike among other mammals, women’s breasts are permanent, from puberty on, not present only during lactation, and composed primarily of fatty tissues, not milk (Møller 1995; Manning et al 1997; Havlíček et al 2016).

In contrast, men possess no obvious equivalent of the ‘peacock’s tail’ (i.e. a trait that has evolved in response to female choice) – though Geoffrey Miller makes a fascinating (but ultimately unconvincing) case that the human brain may represent a product of sexual selection (see The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature).^[2]

Interestingly, in an endnote to post-1989 editions of ‘The Selfish Gene’, Dawkins himself tentatively speculates that maybe the human penis might represent a sexually-selected ‘fitness indicator’.

Thus, he points out that the human penis is large as compared to that of other primates, yet also lacks a baculum (i.e. penis bone) that facilitates erections. This, he speculates, could mean that the capacity to maintain an erection might represent an honest signal of health in accordance with Zahavi’s handicap principle (307-8).

However, it is more likely that the large size, or more specifically the large width, of the human penis reflects instead a response to the increased size of the vagina, which itself increased in size to enable human females to give birth to large-brained, and hence large-headed, infants (see Bowman 2008; Sexual Selection and the Origins of Human Mating Systems: pp61-70).^[3]

How then can we make sense of this apparent paradox, whereby, contrary to Bateman’s principle, sexual selection appears to have operated more strongly on women than on men?

For his part, Dawkins himself offers no explanation, merely lamenting:

“What has happened in modern western man? Has the male really become the sought-after sex, the one that is in demand, the sex that can afford to be choosy? If so, why?” (p165).

However, in respect of what David Buss calls short-term mating strategies (i.e. casual sex, hook-ups and one night stands), this is certainly not the case.

On the contrary, patterns of everything from prostitution and rape to erotica and pornography consumption confirm that, in respect of short-term ‘commitment’-free casual sex, it remains women who are very much in demand and men who are the ardent pursuers (see The Evolution of Human Sexuality: which I have reviewed here).

Thus, in one study conducted on a University campus, 72% of male students agreed to go to bed with a female stranger who approached them with a request to this effect. In contrast, not a single one of the 96 females approached agreed to the same request from a male questioner (Clark and Hatfield 1989).

(What percentage of the students sued the university for sexual harassment was not revealed.)

However, humans also form long-term pair-bonds to raise children, and, in contrast to males of most other mammalian species, male parents often invest heavily in the offspring of such unions.

Men are therefore expected to be relatively choosier in respect of long-term romantic partners (e.g. wives) than they are for casual sex partners. This may then explain the relatively high levels of reproductive competition engaged in by human females, including high levels of what Dawkins calls ‘sexual advertising’.

Reproductive competition between women may be especially intense in western societies practising what Richard Alexander termed ‘socially-imposed monogamy’.

This refers to societies where there are large differences between males in social status and resource holdings, but where even wealthy males are prohibited by law from marrying multiple women at once.^[4]

Here, there may be intense competition as between females for exclusive rights to resource-abundant ‘alpha male’ providers (Gaulin and Boser 1990).

Thus, to some extent, the levels of sexual competition engaged in by women in western societies may indeed be higher than in non-western, polygynous societies.

This, then, might explain why females use what Dawkins terms ‘sexual advertising’ to attract long-term mates (i.e. husbands). However, it still fails to explain why males don’t – or, at least, don’t seem to do so to anything like the same degree.

Darwin himself may have come closer than many of his successors to arriving at an answer, observing that:

“Man is more powerful in body and mind than woman, and in the savage state he keeps her in a far more abject state of bondage than does the male of any other animal; therefore it is not surprising that he should have gained the power of selection” (The Descent of Man).

Therefore, in contrast to mating patterns in modern western societies, ‘female choice’ may actually have played a surprisingly limited role in human evolutionary history, given that, in most pre-modern societies, arranged marriages were, and are, the norm.

Male mating competition may then have taken the form of ‘male-male contest competition’ (e.g. fighting) rather than displaying to females – i.e. what Darwin called ‘intra-sexual selection’ rather than ‘inter-sexual selection’.

Thus, while men indeed possess no obvious analogue to the peacock’s tail, they do seem to possess traits designed for fighting – namely considerably greater levels of upper-body musculature and violent aggression as compared to women (see Puts 2010).

In other words, human males may not have any obvious ‘peacock’s tail’, but we perhaps we do have, if you like, ‘stag’s antlers’.

From Genes to Memes

Dawkins’ eleventh chapter, which was, in the original version of the book (i.e. pre-1989 editions), the final chapter, is also the only chapter to focus exclusively on humans.

Entitled ‘Memes: The New Replicators’, it focuses again on the extent to which humans are indeed an “aberrant species”, being subject to cultural as well as biological evolution to a unique degree.

Interestingly, however, Dawkins argues that the principles of natural selection discussed in the preceding chapters of the book can be applied just as usefully to cultural evolution as to biological evolution.

In doing so, he coins the concept of the ‘meme’ as the cultural unit of selection, equivalent to a gene, passing between minds analogously to a virus.

This term has been enormously influential in intellectual discourse, and indeed in popular discourse, and even passed into popular usage.

The analogy of memes to genes certainly makes for an interesting thought-experiment. However, like any analogy, it can be taken too far.

Certainly ideas can be viewed as spreading between people, and as having various levels of ‘fitness’ depending on the extent to which they catch on.

Thus, to take one famous example, Dawkins famously described religions such as Islam and Christianity as ‘Viruses of the Mind’, which travel between, and infect, human minds in a manner analogous to a virus.

Thus, proponents of Darwinian medicine contend that pathogens such as flu and the common cold produce symptoms such as coughing, sneezing and diarrhea precisely because these behaviours promote the spread and replication of the pathogen to new hosts through the bodily fluids thereby expelled.

Likewise, rabies causes dogs and other animals to become aggressive and bite, which likewise facilitates the spread of the rabies virus to new hosts.^[5]

By analogy, successful religions are typically those that promote behaviours that facilitate their own spread.

Thus, a religion that commands its followers to convert non-believers, persecute apostates, ‘be fruitful and multiply’ and indoctrinate your offspring with their beliefs is, for obvious reasons, likely to spread faster and have greater longevity than a religious doctrine that commands adherents become celibate hermits and that proselytism is a mortal sin.

Thus, Christians are admonished by scripture to ‘save souls’ and ‘preach the gospel’ among heathens; while Muslims are, in addition, admonished to wage ‘holy war’ against infidels and persecute apostates.

These behaviour facilitate the spread of Christianity and Islam just as surely as coughing and sneezing promote the spread of the flu.^[6]

Like genes, memes can also be said to mutate, though this occurs not only through random (and not so random) copying errors, but also by deliberate innovation by the human minds they ‘infect’. Memetic mutation, then, is not entirely random.

However, whether this way of looking at cultural evolution is a useful and theoretically or empirically productive way of conceptualizing cultural change remains to be seen.

Certainly, I doubt whether ‘memetics’, as it is sometimes termed, will ever be a rigorous science comparable to genetics, after which it is named, as some of the concept’s more enthusiastic champions have sometimes envisaged. Neither, I suspect, did Dawkins ever originally intend or envisage it as such, having seemingly coined the idea as something of an afterthought.

At any rate, one of the main factors governing the ‘infectiousness’ or ‘fitness’ of a given meme, is the extent to which the human mind is receptive to it and the human mind is itself a product of biological evolution.

The basis for understanding human behaviour, even cultural behaviour, is therefore how natural selection has shaped the human mind – in other words evolutionary psychology not memetics.

Thus, humans will surely have evolved resistance to memes that are contrary to their own genetic interests (e.g. celibacy) as a way of avoiding exploitation and manipulation by third-parties.

For more recent discussion of the status of the meme concept (the ‘meme meme’, if you like) see The Meme Machine; Virus of the Mind; The Selfish Meme; and Darwinizing Culture.

Escaping the Tyranny of Selfish Replicators?

Finally, at least in the original, non-‘extended’ editions of the book, Dawkins concludes ‘The Selfish Gene’, with an optimistic literary flourish, emphasizing once again the alleged uniqueness of the “rather aberrant” human species.^[7]

Thus, his final paragraph ends:

“We are built as gene machines and cultured as meme machines, but we have the power to turn against our creators. We, alone on earth, can rebel against the tyranny of the selfish replicators” (p201).

This makes for a dramatic, and optimistic, conclusion. It is also flattering to anthropocentric notions of human uniqueness, and of free will.

Unfortunately, however, it ignores the fact that the “we” who are supposed to be doing the rebelling are ourselves a product of the same process of natural selection and, indeed, of the same selfish replicators against whom Dawkins calls on us to rebel. Indeed, even the (alleged) desire to revolt is a product of the same process.^[8]

Likewise, in the book’s opening paragraphs, Dawkins proposes:

“Let us try to teach generosity and altruism, because we are born selfish. Let us understand what our selfish genes are up to, because we may then at least have the chance to upset their designs.” (p3)

However, this ignores, not only that the “us” who are to do the teaching and who ostensibly wish to instill altruism in others are ourselves the product of this same evolutionary process and these same selfish replicators, but also that the subjects whom we are supposed to indoctrinate with altruism are themselves surely programmed by natural selection to be resistant to any indoctrination or manipulation by third-parties to behave in ways that conflict with their own genetic interests.

In short, the problem with Dawkins’ cop-out ‘Hollywood Ending’ is that, as anthropologist Vincent Sarich is quoted as observing, Dawkins has himself “spent 214 pages telling us why that cannot be true”. (See also Straw Dogs: Thoughts on Humans and Other Animals: which I have reviewed here).^[9]

The preceding 214 pages, however, remain an exciting, eye-opening and stimulating intellectual journey, even over thirty years after their original publication.

__________________________

Endnotes

[1] Mutualism is distinguished from reciprocal altruism by the fact that, in the former, both parties receive an immediate benefit from their cooperation, whereas, in the latter, for one party, the reciprocation is delayed. It is reciprocal altruism that therefore presents the greater problem for evolution, and for evolutionists, because, here, there is the problem policing the agreement – i.e. how is evolution to ensure that the immediate beneficiary does indeed reciprocate, rather than simply receiving the benefit without later returning the favour (a version of the free rider problem). The solution, according to Axelrod, is that, where parties interact repeatedly over time, they come to engage in reciprocal altruism only with other parties with a proven track record of reciprocity, or at least without a proven track record of failing to reciprocate. 

[2] Certainly, many male traits are attractive to women (e.g. height, muscularity). However, these also have obvious functional utility, not least in increasing fighting ability, and hence probably have more to do with male-male competition than female choice. In contrast, many sexually-selected traits are positive hindicaps to their bearers, in all spheres except attracting mates. Indeed, one influential theory of sexual selection claims that it is precisely because they represent a handicap that they serve as an honest indicator of fitness and hence a reliable index of genetic quality.

[3] Thus, Edwin Bowman writes:

“As the diameter of the bony pelvis increased over time to permit passage of an infant with a larger cranium, the size of the vaginal canal also became larger” (Bowman 2008).

Similarly, in their controversial book Human Sperm Competition: Copulation, Masturbation and Infidelity, Robin Baker and Mark Bellis persuasively contend:

“The dimensions and elasticity of the vagina in mammals are dictated to a large extent by the dimensions of the baby at birth. The large head of the neonatal human baby (384g brain weight compared with only 227g for the gorilla…) has led to the human vagina when fully distended being large, both absolutely and relative to the female body… particularly once the vagina and vestibule have been stretched during the process of giving birth, the vagina never really returning to its nulliparous dimensions” (Human Sperm Competition: p171).

In turn, larger vaginas probably select for larger penises in order to fill the vagina (Bowman 2008).

According to Baker and Bellis, this is because the human penis functions as a “suction piston”, functioning to remove the sperm deposited by rival males, as a form of sperm competition, a theory that actually has some experimental support, not least from some hilarious research involving sex toys of differing sizes and shapes (Gallup et al 2003; Gallup and Burch 2004; Goetz et al 2005; see also Why is the Penis Shaped Like That).

Thus, according to this view:

“In order to distend the vagina sufficiently to act as a suction piston, the penis needs to be a suitable size [and] the relatively large size… and distendibility of the human vagina (especially after giving birth) thus imposes selection, via sperm competition, for a relatively large penis” (Human Sperm Competition: p171).

However, even in the absence of sperm competition, Alan Dixson observes:

“In primates and other mammals the length of the erect penis and vaginal length tend to evolve in tandem. Whether or not sperm competition occurs, it is necessary for males to place ejaculates efficiently, so that sperm have the best opportunity to migrate through the cervix and gain access to the higher reaches of the female tract” (Sexual Selection and the Origins of Human Mating Systems: p68).

[4] In natural conditions, it is assumed that, in egalitarian societies, where males have roughly equal resource holdings, they will each attract an equal number of wives (i.e. given an equal sex ratio, one wife for each man). However, in highly socially-stratified societies, where there are large differences in resource holdings between men, it is expected that wealthier males will be able to support, and provide for, multiple wives, and will use their greater resource-holdings for this end, so as to maximize their reproductive success (see here). This is a version of the polygyny threshold model (see Kanazawa and Still 1999).

[5] There are also pathogens that affect the behaviour of their hosts in more dramatic ways. For example, one parasite, Toxoplasma gondii, when it infects a mouse, reduces the mouse’s aversion to cat urine, which is theorized to increase the risk of its being eaten by a cat, facilitating the reproductive life-cycle of the pathogen at the expense of that of its host. Similarly, the fungus, ophiocordyceps unilateralis turns ants into so-called zombie ants, who willingly leave the safety of their nests, and climb and lock themselves onto a leaf, again in order to facilitate the life cycle of their parasite at the expense of their own. Another parasite, dicrocoelium dendriticum (aka the lancet liver fluke) also affect the behaviour of ants whom it infects, causing them to climb to the tip of a blade of grass during daylight hours, increasing the chance they will be eaten by cattle or other grazing animals, facilitating the next stage of the parasite’s life-history

[6] In contrast, biologist Richard Alexander in Darwinism and Human Affairs cites the Shakers as an example of the opposite type of religion, namely one that, because of its teachings (namely, strict celibacy) largely died out.
In fact, however, Shakers did not quite entirely disappear. Rather, a small rump community of Shakers – the Sabbathday Lake Shaker Village – survives to this day, albeit greatly reduced in number and influence. This is presumably because, although the Shakers did not, at least in theory, have children, they did proselytise.
In contrast, any religion which renounced both reproduction and proselytism would presumably never spread beyond its initial founder or founders, and hence never come to the attention of historians, theorists of religion, or anyone else in the first place.

[7]  As noted above, this is among the reasons that ‘The Selfish Gene’ works best, in a purely literary sense, in its original incarnation. Later editions have at least two further chapters tagged on at the end, after this dramatic and optimistic literary flourish.

[8] Dawkins is then here here guilty of a crude dualism. Marxist neuroscientist Steven Rose, in an essay in Alas Poor Darwin (which I have reviewed here and here) has also accused Dawkins of dualism for this same passage, writing:

“Such a claim to a Cartesian separation of these authors’ [Dawkins and Steven Pinker] minds from their biological constitution and inheritance seems surprising and incompatible with their claimed materialism” (Alas Poor Darwin: Arguments Against Evolutionary Psychology: p262).

Here, Rose may be right, but he is also a self-contradictory hypocrite, since his own views represent an even cruder form of dualism. Thus, in an earlier book, Not in Our Genes: Biology, Ideology, and Human Nature, co-authored with fellow-Marxists Leon Kamin and Richard Lewontin, Rose and his colleagues wrote, in a critique of sociobiological conceptions of a universal human nature:

“Of course there are human universals that are in no sense trivial: humans are bipedal; they have hands that seem to be unique among animals in their capacity for sensitive manipulation and construction of objects; they are capable of speech. The fact that human adults are almost all greater than one meter and less than two meters in height has a profound effect on how they perceive and interact with their environment” (passage extracted in The Study of Human Nature: p314).

Here, it is notable that all the examples “human universals that are in no sense trivial” given by Rose, Lewontin and Kamin are physiological not psychological or behavioural. The implication is clear: yes, our bodies have evolved through a process of natural selection, but our brains and behaviour have somehow been exempt from this process. This of course, is an even cruder form of dualism than that of Dawkins.

As John Tooby and Leda Cosmides observe:

“This division of labor is, therefore, popular: Natural scientists deal with the nonhuman world and the “physical” side of human life, while social scientists are the custodians of human minds, human behavior, and, indeed, the entire human mental, moral, political, social, and cultural world. Thus, both social scientists and natural scientists have been enlisted in what has become a common enterprise: the resurrection of a barely disguised and archaic physical/mental, matter/spirit, nature/human dualism, in place of an integrated scientific monism” (The Adapted Mind: Evolutionary Psychology and the Generation of Culture: p49).

A more consistent and thoroughgoing critique of Dawkins’ dualism is to be found in John Gray’s excellent Straw Dogs: Thoughts on Humans and Other Animals (which I have reviewed here).

[9] This quotation comes from p176 of Marek Kohn’s The Race Gallery: The Return of Racial Science (London: Vintage, 1996). Unfortunately, Kohn does not give a source for this quotation.

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