Sex at Dawn — Christopher Ryan and Cacilda Jethá

EDIT: This review, from the journal Evolutionary Psychology, is the one I would’ve written if I’d been better read in the field and had more time to read extensively in it. Read the linked review if you really want to understand the problems with Sex at Dawn.

Furthermore, “The Myth of Promiscuity: A review of Lynn Saxon, Sex at Dusk: Lifting the Shiny Wrapping from Sex at Dawn” discusses the (many) problems with Sex at Dawn in a more complete fashion than I did. So if you’re looking for a deeper discussion than the one I can offer, consider Sex at Dusk.

My bottom-line assessment of Sex at Dawn: The Prehistoric Origins of Modern Sexuality is that the book would never get past peer review because so many of its descriptions of existing research and ideas are wrong or skewed. The book argues that humans are not “naturally” monogamous. That might be true. But Sex at Dawn doesn’t prove it. The data are ambiguous.

The biggest problem with the book starts on page 46, with the chapter “A Closer Look at the Standard Narrative of Human Sexual Revolution.” But there is no standard narrative of human sexual revolution: there are a wide array of people who have made inferences about the evolutionary basis of sexuality, but their narratives aren’t consistent and new papers and ideas constantly jostle or replace old ones. Ryan and Jethá don’t cite anyone else who claims a “standard” narrative, because to my knowledge no one has, and the standard narrative they cobble together is just that: cobbled together from a variety of sources with a variety of views.

I mentioned the lack of citations as a problem that occurs in their chapter on the standard narrative. It continues throughout the book. On page 293, Ryan and Jethá say that “To avoid the genetic stagnation that would have dragged our ancestors into extinction long ago, males evolved a strong appetite for sexual novelty and a robust aversion to the overly familiar.” But they don’t have any evidence for that. Similarly, they accuse scientists and others of claiming that monogamy is “natural” or inborn and cite, the anthropologist Owen Lovejoy as saying, “The nuclear family and human behavior may have their ultimate origin long before the dawn of the Pleistocene” (34). And he’s right: such behaviors may have their origins there. Or they may not have. Good scientists tend to be more tentative than polemicists because scientists recognize the fragility of so much human knowledge.

In Melvin Konner’s The Evolution of Childhood, he writes:

A double standard of sexual restriction is common across cultures; still, most human marriages have been mainly monogamous, owing either to environmental constraint or cultural principle. Modern cultures are monogamous in principle, but both adultery and serial monogamy are common. In at least thirty-seven countries, men express preference for women several years younger than themselves and place more emphasis on appearance, while women prefer men several years older and emphasize status and wealth (41).

The “environmental constraint” is important because it takes a lot of resources to support multiple spouses; this means that most men in most places and most conditions cannot afford to support multiple women. One woman might be able to support or be supported by multiple men, but polyandry is far less common than polygyny, as Konner points out. This is probably as close to accurate as one is likely to get regarding the historical or anthropological record on the subject of polygamy. It also has the advantage of coming from someone who spent his entire career on the subject of childhood development and who is deeply familiar with the vast literature surrounding evolution, anthropology, and childhood.

Ryan and Jethá also have many sections where they ask rhetorical questions or pit themselves against imaginary foes of great power; the page after the Lovejoy quote, they say, “This is what we’re up against. It’s a song that is powerful, concise, self-reinforcing, and playing on the radio all day and all night . . . but still wrong, baby, oh so wrong” (35). Enough with the polemics: if you’re right, show us that you’re right and leave the judgment up tot he reader.

Dan Savage called Sex at Dawn “the single most important book about human sexuality since Alfred Kinsey unleashed Sexual Behavior in the Human Male on the American public in 1948.” The statement is hyperbolic and unlikely but nonetheless demonstrates the power of the book, especially when America’s most famous sex columnist is pimping it, so to speak.

In addition, Kinsey was at least doing original research by taking and compiling sexual histories. Ryan and Jethá aren’t: they’re rehashing a variety of other people’s research, and in doing so regularly misrepresenting that research. Furthermore, Kinsey was reacting to a much, much different culture than ours today; Sexual Behavior in the Human Male had essentially no real forerunners, while Sex at Dawn is a weak entry to a crowded field of evolutionary biologists and psychologists like Geoffrey Miller (The Mating Mind), Sarah Blaffer Hrdy (The Woman Who Never Evolved, and David Buss). All three get cited, but out of context, and their deeper arguments are never really engaged. I don’t think it a coincidence that all three are academics.

For another example of imprecision in Sex at Dawn, Ryan and Jethá point out that men are only 10% – 20% larger than women (in polygynous species, the larger the size difference between sexes, the greater the number of sex partners). But that raw size or height difference way underestimates how that size translates to muscle. Consider David Potts’ work:

When fat-free mass is considered, men are 40% heavier (Lassek & Gaulin, 2009; Mayhew & Salm, 1990) and have 60% more total lean muscle mass than women. Men have 80% greater arm muscle mass and 50% more lower body muscle mass (Abe, Kearns, & Fukunaga, 2003). Lassek and Gaulin (2009) note that the sex difference in upper-body muscle mass in humans is similar to the sex difference in fat-free mass in gorillas (Zihlman & MacFarland, 2000), the most sexually dimorphic of all living primates.

These differences in muscularity translate into large differences in strength and speed. Men have about 90% greater upper-body strength, a difference of approximately three standard deviations (Abe et al., 2003; Lassek & Gaulin, 2009). The average man is stronger than 99.9% of women (Lassek & Gaulin, 2009). Men also have about 65% greater lower body strength (Lassek & Gaulin, 2009; Mayhew & Salm, 1990), over 45% higher vertical leap, and over 22% faster sprint times (Mayhew & Salm, 1990).

(That’s from Puts, David, A. “Beauty and the Beast: Mechanisms of Sexual Selection in Humans.” Evolution & Human Behavior 31.3 (2010): 157-75.)

The weird thing is that this information supports their assertion that humans are polygynous but hurts their assertion that early societies were mostly kind and peaceful, which they probably weren’t, per Lawrence Keeley’s War Before Civilization. Both the Potts paper and the Keeley book are the kinds of things that peer reviewers should be apt to point out.

Even when they aren’t simplifying the research others have done or selectively quoting writers without fully engaging in their arguments, Ryan and Jethá are merely poor writers. Take this: “For better or worse, the human female’s naughty bits don’t swell up to five times their normal size and turn bright red just to signal her sexual availability,” which is true in many species of apes. But note how bad this writing is: the sentence starts with a cliche, moves on to a childish description of women more appropriate to 14-year-olds than a real book and that also reinforces the very cultural forces the authors are trying to counteract, and then proceeds to something that has already been stated earlier in the chapter. The writing in much of the book is equally bad, the reasoning sloppy, and the thought underdeveloped. Which isn’t to say the book doesn’t have interesting or useful elements—it does—but those tend to get subsumed by its flaws.

The more I read about humanity, history, and the rhetoric of authenticity, naturalness, human instinct, and the like, the more I think there aren’t such things and the claims about what is “natural” reflect more about the person making the claim than anything about humanity itself. I would say that it’s natural for people to make claims about what is natural, but relatively little else is; circumstances affect so much that it’s hard to perceive many higher order behaviors as anything other than reflecting the bizarre combinations of self and environment.

People simply vary widely in their preferences, and most appear to view whatever society and subculture they grew up in as normal and natural. I posit that it’s not normal or abnormal to be polygamous or monogamous: in some circumstances one might make more sense, and in others the other strategy would. And people are too variable to say one mode is completely correct for all people under all circumstances.

I had actually begun this post before I read Paul Graham’s latest essay, “The Top Idea in Your Mind.” This part especially resonated:

I’ve found there are two types of thoughts especially worth avoiding—thoughts like the Nile Perch in the way they push out more interesting ideas. One I’ve already mentioned: thoughts about money. Getting money is almost by definition an attention sink. The other is disputes. These too are engaging in the wrong way: they have the same velcro-like shape as genuinely interesting ideas, but without the substance. So avoid disputes if you want to get real work done. [3]

To really catalog everything that’s wrong with Sex at Dawn, I’d have to go back through at least five or six books (and probably more) and at least a dozen papers. It would take me all day. Why spend that much time on a book that’s not very good? A while ago I promised myself that I wasn’t going to write many more posts on books that are bad in a generic way that doesn’t do anything special because I’m usually not spending my time in an optimal way. And reading Sex at Dawn is unlikely to be an optimal use of your time.

40 responses

  1. Hey. Thanks for the review. Sorry to see you hated the book. I won’t get into a tiresome point-by-point, but you wrote:

    “The weird thing is that this information supports their assertion that humans are polygynous but hurts their assert (sic) that early societies were mostly kind and peaceful, which they probably weren’t, per Lawrence Keeley’s War Before Civilization. Both the Potts paper and the Keeley book are the kinds of things that peer reviewers should be apt to point out.”

    We never assert that humans are polygynous. And we talk about Keeley’s book, by name, on pages 184 and 330-331.

    Aside from somehow missing the central argument of the book—that humans evolved not to be monogamous or polygynous—I could point to a lot more that you missed. But as you say, it’s not an optimal use of time. Thanks for the review though, and best wishes to you.



  2. You write “males evolved a strong appetite for sexual novelty and a robust aversion to the overly familiar.” But they don’t have any evidence for that

    Jake, if this is the kind of thing that you need ‘evidence’ for then I am going to go out on a limb and advise you to see a doctor about having abnormally low testosterone levels. If this isn’t a point that your own biological experience confirms for you then I think you have a health problem. And in either case, just turn on the TV. Tiger Woods ring a bell?

    This is just not a controversial point at all, and I suspect that if the authors neglected to elaborate on this point with evidence it is because it would be exhausting to do so, and not because they were lacking sufficient amounts.


      • Thank you, Jake! As a woman I find much of this research about the differences between male and female sexual response and behavior to be steeped in stereotypes about female lack of desire and bias against females as agents of their own sexuality. It’s very annoying to have “scientists” tell you that you don’t feel what you feel (desire), that you don’t experience what you experience (desire followed by censure or threat), or that it doesn’t matter (just put up with it because we’re wired that way). Then you look across the aisle and see these same “scientists” telling a whole other group that yes, you feel what you feel, your experience is valid, and you’re wired that way. Very annoying.


    • I beg to disagree: I really, really, don’t want anyone beside my wife of 32 years, and my testosterone levels are fine. I’m afraid your statement boils down to ‘Either you are a man like me or you are less [of|than] a man,’ which is not argument but abuse, which as an old television programme observed are in different rooms.

      Perhaps there is a basic human dimorphism here; in that case, I must apologise for those people like me (monogamous by nature) who might refuse to believe that there is any other authentic human way-of-being, but your response should not be to ape them in intolerance born of lack of imagination. (Perhaps the most vociferous critics of polyamory are those who are _not_ monogamous by nature, but feel the need to defend the idea; for my part, I have never had any trouble with the idea that something very different from what I want works best for many other people….)

      I do have to say that the broadness of the brush, the use of straw-men, and the disingenuousness of the authors in denying that they are being normative (“We’re not saying this is better, just that you will probably suffer if you don’t act in this way, which was the way all humans everywhere did back in our paradaisical pre-agricultural state, or at least believe that we are absolutely right….”). It is not argument; it is apologetics.


  3. The strength or weakness of the book ultimately relies on how much the authors paid attention to the fact that sex must be reproductive. As such, no argument for a sexual strategy works without considering–so what happens to the babies? Monogamy happens to be great for babies because it brings a resource provider into the picture (as well as another set of hands and eyes for protection against predators). Also reduces the likelihood of infanticide by a male who wants mom to stop nursing. Which isn’t to say that monogamy was our original strategy. But there are a lot of ways to spin the argument of sexual selection (and I’m not proposing that our ancestors were totally monogamous–mainly providing the counter argument of why it is a useful strategy).

    Any argument that thinks only of number of possible offspring, rather than quality of those offspring’s future reproductive fitness is not one worth listening to. There are a wide range of troubles with human babies that are probably what drives us to a semi-monogamous sexuality. Addressing those issues is more likely to lead us to an understanding of human sexuality than what our desires or cultural norms will lead us to believe.

    I am curious did this book address any of those issues?


    • The short answer is, “somewhat.”

      The longer answer is that evolutionary biologists and psychologists have spent a lot of time analyzing those questions, and the longer answer is that sexual strategies probably change based on context and the probability of male parental investment (“MPI” in the lingo). For more on that, see Cashdan, Elizabeth. “Attracting Mates: Effects of Paternal Investment on Mate Attraction Strategies.” Ethology and Sociobiology 14.1 (1993): 1-23 ; Geoffrey Miller’s The Mating Mind; and Melvin Konner’s The Evolution of Childhood. The latter is probably especially useful but also quite dense. All three have the advantage of better support than Sex at Dawn.


      • I’m familiar with the MPI and it is part of why I was curious if Sex at Dawn had even ventured into that territory. Any time I’ve discussed my area of study with others (particularly men) they tend to hone in on bizarre ideas of human sexuality based more off of fantasy and culture than anything that is supported by the mechanisms of evolution.


    • “Monogamy happens to be great for babies because it brings a resource provider into the picture (as well as another set of hands and eyes for protection against predators).”

      Hi. We do discuss the issues you raise in our book. Jake seems to have missed much of this discussion, but I assure you that it’s there.

      As per monogamy, the problem is that while it can bring a resource provider, as you say, the stability of this provider is weakened by the constant lure of other sexual partners—hence the strict legal structures built up to try (albeit unsuccessfully) to buttress marriage-based economic ties. What we argue in Sex at Dawn is that the economics of h/g life made this particular exchange of sexual fidelity/parental certainty for status/material support/protection largely unnecessary. We discuss the importance of MPI in some depth (several pages devoted to a summary of the theory as well as further discussion throughout the book).


      • Jake seems to have missed much of this discussion, but I assure you that it’s there.

        I believe that you discuss it, but there are better discussions of it out there: that’s why I pointed to here:

        “For more on that, see Cashdan, Elizabeth. “Attracting Mates: Effects of Paternal Investment on Mate Attraction Strategies.” Ethology and Sociobiology 14.1 (1993): 1-23 ; Geoffrey Miller’s The Mating Mind; and Melvin Konner’s The Evolution of Childhood. The latter is probably especially useful but also quite dense.”


  4. “I believe that you discuss it, but there are better discussions of it out there: that’s why I pointed to here:”

    No, their discussion is pretty solid, and they poke some solid holes in the people you cite. The authors make a solid case that a female sired better offspring by letting lots of males have their way and letting the sperm duke it out.

    The case is very strong. Given our genital physiology and close resemblance to bonobos, it looks like the authors are right about fundamental points.

    I’ll grant you that their tone is breezy and occasionally sophomoric, and they suffer from some silly leftist posing, the the book’s still a winner.


  5. Jake regarding your statement, “The “environmental constraint” is important because it takes a lot of resources to support multiple spouses; this means that most men in most places and most conditions cannot afford to support multiple women.” Are you saying that is what Melvin Konner meant by ‘environmental constraint’? How do you know that? Did you have conversations with him, or can you cite his definition?
    I personally don’t believe that a monetary constraint is what keeps men from wanting or having more than one woman anyway. His penis doesn’t know if his billfold is empty or full of cashola.


  6. Sorry about typos. I typed that on my phone. I also rushed through what I was going to say because people that disagree with me and the authors of this book are going to continue to do so no matter what. I just wanted the author to know that I and many others agree with much of what was written in this book. It’s hard to really apply it to modern life and doing so wouldn’t work out too well, because of our altered culture. But the book brings a lot of hope in other regards; reminding us that we aren’t inherently the way we are now in any capacity. That we aren’t “meant” to compete with each other and use each other for selfish gain, just because some other animals do. We were once intimate and entwined so deeply with those around us that modern man can’t even comprehend the word “love”.


    • I just wanted the author to know that I and many others agree with much of what was written in this book.

      The questions I raise are not about whether I agree or disagree with “much of what was written”: the questions deal with whether or not the book draws appropriate conclusions from what research it cites, and whether it deals well with that research. The answer is “no.” The book’s conclusions might still be right even if its premises are flawed: we don’t have enough information to judge. Some of the alternatives I cite in the post itself and elsewhere do a better job; see, for example, Melvin Konner’s The Evolution of Childhood.


  7. I just finished the book last night. And I’d have to agree with many of the points raised here, especially the glib and facile style with which Ryan and his co-author write.

    I find it suspicious that they decided to publish this in book form (to great fanfare) rather than in peer reviewed journals or both. Ryan only cites two of his published works in the reference section, neither of which directly address the main claims of the book.

    I enjoyed their perspective. I too think the institution of marriage is a procrustean bed. But I long for a deeper explanation of the evolutionary arguments behind their unknown paternity theory. Ryan claims this leads to stronger forms of cooperation and solidarity, but it’s not explained how the ancestral environment would select for this over a group that did not embrace bonobo like swinging.

    Furthermore, Ryan criticizes others for using modern evidence to create descriptions of hunter gatherer life, but then he offers nothing in it’s place. The only thing we’re left with a description of a lazy jet set that constantly moves around.

    Lastly, Ryan doesn’t address female hypergamy other than to suggest that it might have only arises after civilization started. Why women prefer alpha over beta is a problem that needs to be addressed on the bonobo orgy theory.


  8. Jake, peer review matters in the academy, but I do not believe that Ryan/Jetha are addressing academic anthropologists. Neither – as you accurately observe – have they contributed a body of primary research that makes novel or affirmative claims about prehistoric human sexuality. Their project is actually much more interesting. Their undertaking, conducted in an unapologetically mainstream context (I bought my copy at the airport!) subverts the casual certainty that practically all lay people feel in believing that contemporary social conventions such as marriage and monogamy have certain origins in the prehistorical past, and are the more-or-less direct product of evolutionary biology, case closed. In short, most people believe that marriage (or something very analogous to it) is a prehistorical fact that is now merely dressed in the forms and fashions of their own times. They believe that there is such a thing as human nature and that it extends at least into the deep past where it was originally formed. And they believe that that nature is fundamentally monogamous, possessive, jealous. Most of all, they believe that evolution decisively and unambiguously buttresses these models.

    Ryan/Jetha have distinguished the assumptions about our origins that most of us hadn’t realized we’d made and didn’t know were assumptions or, if we had recognized them at all, believed to be the unified conclusions of evolutionary biologists. In this they have done a great service. Even if future anthropological studies were to demonstrate to the conclusive and peer-reviewed satisfaction of academics that we are more chimp than bonobo, the science isn’t there yet, an assertion with which I think even you would agree.

    The great contribution of “Sex at Dawn” does not lie in the conclusive demonstration of a contrary scientific narrative or a novel prescription for contemporary behavior. The contribution of “Sex at Dawn” consists of its successful introduction of a seminal question into the thinking of non-scientists: Do our cultural arrangements support the aspects of our sexual nature bequeathed to us by evolutionary processes, or are they more or less in conflict? Are we designed by evolution for monogamous pair-bonding or not?

    These are magnificent questions, questions without decisive answers so far, but legitimate and vital questions nonetheless. The authors, very much to their credit, do not leap to any grand program of social or cultural redesign. I couldn’t find the quote in my copy of the book but I distinctively recall reading something like “we’re not even sure what to do with this [model of prehistoric sexuality].” The book seems to me very likely to exert an enduring impact on the manner in which people think about contemporary human sexuality. I think it’s already in its third printing. By throwing open the conversation about the evolutionary origins of relationships between men and women – and exposing a very wide audience to a range of possible conceptual models – Ryan/Jetha have shaken loose the unscientific and frankly rather gloomy certainty inside of which most people think. Like you, Jake, I personally would have preferred a less conversational and polemical style, but it’s hard to argue with success. This book is being and will be widely read, discussed and pondered. The authors have accomplished their goal. They have delegitimized an undeserving but popular “consensus” and stripped it of its rather phony scientific veneer. They have shown it to be one possible model. If their alternative model does not convincingly persuade it at least exposes the uncertainty in this branch of modern thought. It seems only fair to challenge or criticize them for the book they actually wrote rather than the one we might wish they had written instead.


    • I can claim Sex at Dawn wouldn’t get past peer review because it contains too much misinterpretation. As Megan McArdle observes in a different context, peer review is hardly a panacea, but it is pretty effective at filtering outright nonsense, people who haven’t done their research, people who have misinterpreted their research, and people who have missed important ideas / sources in their field. The point of saying that Sex at Dawn wouldn’t get past peer review is that the book is half-baked and consequently not worth reading, especially when there are books on the subject that *are* worth reading.

      These are magnificent questions, questions without decisive answers so far, but legitimate and vital questions nonetheless.

      And some people answer them better than others. See, e.g., The Evolutionary Biology of Human Female Sexuality, which I’m going to write a post on shortly.


    • Hi, thanks for the great explanation. One thing I’m not clear on: who are those people who assume that monogamy is our innate human nature, whom the authors are targeting? I assume it’s a non-expert public, because I don’t know of any scientific camp (though I’m only very familiar with the literature in the psych area) who would espouse this. Thanks for your thoughts if you can respond.



  9. Pingback: Overcoming Bias : Sex At Dawn Is Right

  10. Hi guys
    Just a quick note regarding novelty seeking behaviour: In my experience there is no doubt that we need novelty to arouse us, that’s what makes fantasies and internet porn so useful. When I say “we” I mean females as much as males.
    I’m reading “Sex At Dawn” at the moment and so far tend to agree with Dan Savage. The idea that humans originally lived in family groups without boundaries (in every sense) is the only one that makes sense. In such a society there is no need for lasting monogamous pair bonds since the group takes care of everything, including children.
    “Sex At Dawn” talks about community, so central to this hyper-social being called Homo Sapiens.


  11. Mike- It ought to be obvious why disregard for paternity was the optimal rule in a tribe of humans: each individual member received the full support of their group, conferring on the group and its members an advantage over the individual who had a more narrow access of support. It was more important that the tribe thrive than that any particular sons and daughters do so, and this worked admirably well for the tribe’s members in general.


    • You really have no idea how wrong this thinking is.
      For a start, people don’t just spend their lives in the group they are born into.
      In the past, extended family groups were not inbreeding groups separated from others but people moved between them (just like sexually mature males and/females move between groups of other primates) and in humans created extensive networks – based on marriage ties.

      Kinship relations in humans are massively inportant and concern paternal lines as well as maternal. Without paternity we could not have this.
      See for example:

      ‘In-laws transformed early human society’

      “That conclusion stems from an analysis of genealogical and marital data indicating that, among modern hunter-gatherers, monogamous sexual unions between men and women from neighboring groups create networks of in-laws that spawn widespread cooperation and cultural learning, says a team led by anthropologist Kim Hill of Arizona State University in Tempe. Social groups organized in this way distinguish humans from other primates, Hill and his colleagues propose in the March 11 Science.”

      ‘Primeval kinship: how pair-bonding gave birth to human society’
      By Bernard Chapais


      • That link doesn’t work for me; do you happen to know how they establish monogamy in fact rather than in name, and how far back the research spans?


      • Interesting. I can’t claim to be well versed in the techniques used, but unless I misunderstand, the idea is that groups with common ancestors most likely inherited shared cultural traits? That seems reasonable, but the claim “Marginal habitats, pressure from agricultural neighbors, and assimilation and acculturation into state-level societies have all significantly affected hunter-gatherer lifeways. However, these processes have most likely served to disrupt traditional cultural norms [25] in ways that simplify or de-regulate marriage practices, as opposed to strengthening marriage regulation” seems like a large leap to take, especially when “The reconstruction of low levels of polygyny in early humans is straightforward because high levels of polygyny for hunter-gatherers are only found in Australian Aborigines and are mostly low elsewhere (most exceptions are some New World foragers that are not in the phylogenetic analysis).”

        The latter quote would seem to indicate that those areas with the LEAST pressure from agricultural neighbors and assimilation were the MOST likely to have an alternate marriage structure.


      • I think you may have misunderstood something along the way. They state:

        “Case in point is Australia where Aborigines across
        the continent heavily regulated marriage probably over many
        millennia and had no traditional exposure to agriculture.”

        They have heavily regulated marriage with more polygyny – not an alternative to regulated marriage with some level of polygyny. They are looking for alternatives to regulated marriages.


      • I see – thanks for clarifying?

        So by “alternatives to regulated marriages” are they looking for something more akin to Herodotus’ description of the Scythians, with no formal marriage and children assigned to the adult they most resembled?


      • I see – thanks for clarifying!

        So by “alternatives to regulated marriages” are they looking for something more akin to Herodotus’ description of the Scythians, with no formal marriage and children assigned to the adult they most resembled?


      • They are looking at the history of marriages arranged between groups compared to how likely people were able to court each other and choose their own spouse. This obviously matters when considering sexual selection in humans – ie how much people have been able to make their own mate choices as opposed to the mate choices being those made for them.

        The extent of brideprice and brideservice etc suggests arranged marriages between groups has a deep history.

        Chimpanzees and bonobos have males staying for life in their birth group. They have no connections beyond the group. Females change groups at puberty.

        Humans, in contrast, extended their network of relations across groups, and therefore extended cooperation via marriage – marriages arranged by groups because creating these links through marriage was important to the group. Indivdual and personal choice of spouse might go against the interests of the group seeking connections to other famiies/groups.

        The fact that males can go to the family of their bride and live with them while they work to ‘pay’ for their bride makes us very different from our ape cousins.
        Ultimately our male ancestors were able to move and live in groups other than their natal group.

        Through marriages across groups extensive networks meant that people, often in their nuclear family groups, could move to other groups for resources – they would have a kin memeber either of the husband or the wife in many other groups.


  12. My bottom line assessment of this review is that you’re missing the forest for the trees. You can poke holes in passages from just about any book, but you haven’t really engaged the central thrust of their book, which as I read it is that much of the current literature makes unwarranted assumptions, and that the concepts of monogamy/polygamy etc… were not as relevant for most of pre-agricultural history.

    You seem to be guilty of much the same crime you accuse the authors of: In search of a catchy article you are too categorical in your dismissal of the book, basically saying it is worthless, without really engaging in the meat of the argument.

    You raise some valid points regarding the tone of the book, and certainly I’m sure there are mistakes made, but I think you are being a bit too smug in your criticism, especially when you say it isn’t even worth your time to engage with it. I for one think it is worth reading for its willingness to present a reasonably plausible alternative to “conventional” evolutionary psychology.


  13. “there is no standard narrative of human sexual revolution” What? Anybody who thinks there is no “standard narrative” has never read an anthropology textbook or taken Sociology 101. Of course there is a standard narrative. Its number one assertion is that monogamous marriage is a human universal. The standard narrative of sociobiology is that woman have more invested in sex than men, therefore their strategy is to select the best provider and protector, the guy who will stick around after conception. Men have less invested therefore their strategy is to scatter their seed. Neither of these standard narratives are supported by observation if we just look objectively at what we see, instead of looking to confirm our theories of what is “normal” and “universal” for our species. “Sex at Dawn” does a good job of challenging the standard narrative. If anthropologists classify any mating arrangement they see as marriage, and any variation from that as “cheating on a mate”, we might suspect a confirmation bias at work. That is the central point of “Sex at Dawn”, a point this reviewer did indeed seem to miss.


    • Marriage is almost universal. Exceptions are extremely rare and there are no exceptions in traditional hunter-gatherers.
      Most human societies have allowed men to have more than one wife, though few can afford to do so and some will have no wife.
      The rare exceptions are when both parents stay in their own birth group and mother’s brother takes on the male parental role.

      And the same for paternal lineages being almost universal ie kin connections through fathers. It is these which are believed to have enabled the complex network of human relations that allowed increasing numbers of groups of kith and kin to be connected through marriage.

      For humans fathers and brothers have often selected husbands for daughters and sisters – including in hunter-gatherers. Marriage has had an extremely important role in connecting groups of people and access to each others resources. Human females probably had – and often still have – the least control over who they mated with compared to other species

      Across most species it is the females who are more choosy about mates. Female mate choice is a major part of Darwinin natural selection ie sexual selection). Darwin fought long and hard on this aspect of his theory though it was not fully accepted for a hundred years. It is because we almost aways have monogamous marriage and male parental investment that male mate choice/choosiness exists in human males regarding a wife/mother of his children in which he’ll invest, but much less choosiness re. casual sex when any offspring will not be provided for by the opportunist male.

      The widespread scientific view that we are largely monogamous with some polygyny and some polyandry still stands.
      The ‘myth of monogamy’, if such a myth ever existed, has surely not been believed for decades.
      Ryan can try all he likes to create a ‘myth of promiscuity’ – it usually comes up every so often – but the evidence certainly does not support this myth.


  14. Thank you for this deeper review. I spotted this book in my local bookstore, or rather its finnish translation and was a bit doubtful of its back covers boasts. Usually it seems that books claiming to be totally revolutionary are rarely that and rarely based on solid research. I haven’t yet read it, but I’d rather read something more academic, even if it is dense. A warning sign was also that the book’s wikipedia article sited only journalistic rave reviews and no mention of peer review at all.

    Someone commented that the multi-paternal orgy system somehow makes more sense. Another based his agreement with the book on anecdotes and yet another claimed its basic arguments are solid, even without evidence. But how could they make sense or be solid without evidence?

    Another point is that somehow these arguments on how we have strayed away from some pure evolutionary or “natural” path seem very misleading. Is there any reason to think, that modern human societies are not subject to those same laws of evolution that the prehistoric ones were, or that they were somehow better at evolution? But that is simply silly, since evolution is a law of nature and continues to function in all circumstances. I do believe that human reproduction is heavily dependent on circumstance; indeed, flexibility in this is a great evolutionary advantage and explains the origin of all the myriad sexual practices and preferences extant. But the whole object of studying human sexuality to start prescribing right and wrong sexual behaviour seems misguided. I myself am (currently) monogamous and surely, if I wanted, I could cheat on my wife, but I have no interest to do so. So, basically, if we argue, that in some idyllic past, the sexual practice of humans was somehow better or more natural, that means that me and similar people are somehow… breaking the laws of nature or what?

    As you said, this definition of the word natural seems to be made only to make the definer’s argument more solid. Because sensibly, whatever happens, must be natural on some level, so if it is not evolutionary sound then surely, by the definition of natural selection, we would not be able to reproduce succesfully! But still me and for thousands of years others have managed to produce succesfull offspring, so clearly it is not categorically a deadend in evolutionary terms.

    I don’t know whether I’ll read this book, and sure, it can shed some light on certain ways of human behaviour(isn’t there differences in behaviour between different bonobo populations too?), but it sounds a bit too prescriptive and polemical in general terms.


  15. To Janne Kirjasniemi:

    This is a work of popularization, not an academic work, and I don’t think anyone is pretending that it is. It seems ironic that your criticism is that it isn’t adequately sourced, while you fully admit you haven’t even read the book, as is obvious by the numerous straw men you present here. The argument of the book is not that we are in an “unnatural” state, but rather that we should properly understand our evolved heritage. They simply argue that many assumptions and arguments are made that are not founded on good research, but rather on our own biases. I would advise reading the book, it isn’t difficult, and drawing your own conclusions rather than relying on this quite slanted review, which never addresses the primary argument of the book.


    • “They simply argue that many assumptions and arguments are made that are not founded on good research, but rather on our own biases.”

      The interesting part is that Jake’s criticism is exactly that the authors don’t follow this prescription either, that they partly base their argument on “common sense” (prejudices, cliches, call it as you wish) rather than cite evidence for their claims.

      There are enough “popular science” books out there that under the pretext of making cutting edge science digestible claim that what we believed intuitively was right all along. If they claim scientific value, no matter whether or whether not they target a larger audience, they should write with scientific standards.


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