Beauty’s Daughter

fiskesmallI love evolutionary biology, so I love this argument: Beauty is more valuable to girls than it is to boys, so beautiful parents should have more daughters than sons. You want (or at least your genes want) to pass on your assets to children who can make the best use of them.

So I was delighted by recent news reports that beautiful women do indeed have more daughters. But I was stunned by the reported magnitude of the effect: According to one report, beautiful people are 36 percent more likely to have a daughter than a son!

If that’s true, it throws a whole new light on certain divorce statistics. On average, parents of daughters are more likely to divorce, and I’ve argued (here, here and here, citing research by Gordon Dahl and Enrico Morretti) that daughters probably cause divorce. But now we have a rival theory: Perhaps beauty causes both divorce and daughters.

It’s not hard to see how beauty might (on average) cause divorce; for example, it seems likely that the proverbial “trophy wives” are both disproportionately beautiful and disproportionately likely to be dumped when their beauty fades. So if the beautiful really have 36 percent more daughters, that’s plenty big enough to explain the daughter/divorce correlation.

But I don’t believe it. First, the “36 percent” number is just sloppy reporting. The actual number—which I found in the original paper by Satoshi Kanazawa of the London School of Economics—is 26 percent. (He’s also written a book on this and related research, which I have not read.)

Twenty-six percent is still huge. But it’s also probably spurious. For starters, the sample size is pretty small. Professor Kanazawa started with a sample of about 3000 women, rated from 1 to 5 on attractiveness. (I’ll tell you later where the ratings came from.) Of these women, about 350 were rated 5, and it’s true that these women had a great preponderance of daughters. But that’s a pretty small sample—small enough that there’s about a 5% chance the result is just a statistical fluke. (By contrast the
daughters/divorce study by Dahl and Moretti was based on a sample—drawn from census data—of 3 million.)

Worse yet, those women rated 4 (“attractive” as opposed to “very attractive”) had a great preponderance of sons. Sons were in fact much more common among both the “unattractive” 2’s and the “attractive” 4’s, while daughters were much more common among the 5’s. Among the 1’s and 3’s (“very unattractive” and “average”), the sex ratio is 50/50. Not much of a pattern there.

In fact, Professor Kanazawa’s strong result relies crucially on the fact that he lumped the 1’s, 2’s, 3’s and 4’s into a single category and compared them to the 5’s. If he had lumped the 4’s and 5’s together into a single category called “above average”, he’d have gotten a very different result.

In fact, there are a lot of ways to lump these data, and each way of lumping them gives you another shot at finding a statistical fluke. Given that the sample size makes flukes pretty likely to begin with, it’s not at all unlikely that the professor managed to stumble across one.

And there’s another problem. The sample consists of mothers who were interviewed about their families and then rated for attractiveness by the interviewer. It is not at all implausible to me that a mother talking about her daughter–or holding a little girl on her lap—might present, on average, a different appearance than a mother talking about her son. So the attractiveness ratings are contaminated from the get-go. I would have found this study a lot more convincing if the attractiveness ratings had been based on wedding photos, or other photos from before the children were born.

In fact, all of the mothers in the sample were between the ages of 18 and 28, which means that all the children in question were very young. I’ve watched enough toddlers in my life to believe that, on average, the mother of a two year old boy is going to look a little more haggard than the mother of a two year old girl—possibly enough to keep her out of that “very attractive” category. If Professor Kanazawa has discovered anything at all, I suspect it’s not that beauty causes girls but that boys can run you ragged.

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35 Responses to “Beauty’s Daughter”


  1. 1 1 dave

    i dont buy it at all.

    1} women always donate their x. it’s the fathers contribution that ultimately determines the physical gender of the offspring.

    2} (anecdote) there were a large number of daughters born to my cohorts in the nuclear navy. rumor had it that stress caused more daughters than sons. perhaps having a beautiful (wife) is more stressful. =]

    3} ive heard its most dependant on the womans diet and therefore her mucous ph.

  2. 2 2 Harold

    I think it is well established that beauty of women is ranked on a scale of 1 to 10.

    It is the fathers X or Y that fixes the gender, but I think there is generally a good correlation between beauty of women and their partners – scewed a bit by wealth.

    Re data grouping after the results are in – Ben Goldacre (Bad Science column and blog) put it rather well “Imagine I am standing near a large wooden barn with an enormous machine gun. I place a blindfold over my eyes and laughing maniacally I fire off many thousands and thousands of bullets into the side of the barn. I then drop the gun, walk over to the wall, examine it closely for some time, all over, pacing up and down: I find one spot where there are three bullet holes close to each other, and then I draw a target around them, announcing proudly that I am an excellent marksman. You would, I think, disagree with both my methods and conclusions for that deduction”

  3. 3 3 neil wilson

    Probably not the place to post this but I have always wondered why the correlation is so great between belief in evolution and support for the estate tax.

    Steve Landsburg is obviously one of the exceptions who believes in evolution and wants to repeal the estate tax.

    I am one of the overwhelming majority where knowing I believe in evolution tells you that I also support the estate tax.

    I can’t think of any reason for this to be true except political affiliation. Can you think of another explanation?

  4. 4 4 Leah

    I have been told that “male” sperm swim faster but also die faster, whereas “female” sperm swim slower but live longer. So if you want to have a girl, you have sex before ovulation, because the girl sperm take a while to get to the egg but survive the trip, and if you want to have a boy, you have sex during or immediately after ovulation, because the guys can beat the gals to the egg if it’s right there waiting for them.

    So maybe men just want to (and do) have more frequent sex with beautiful women? Meaning that there are more “female” sperm around to fertilize eggs when they are released?

  5. 5 5 Philip

    Neil Wilsom raises some interesting questions. Here are some results from a 2006 survey by The Pew Forum on Religion and Public Life (marin of error 3.5%, though it’s larger on sum of the sub-questions I provide):

    * 42% of Americans believe that humans and other living things have existed in present form only, while another 21% believe they have evolve over time guided by a supreme being (intelligent design).

    * only 26% believe they evolved over time through natural selection.

    * 93% of white evangelicals reject natural selection with either classic anti-evelution (65%) or by intelligent design (28%) beliefs.

    * In contrast 69% of secular Americans accept natural selection and only 6% believe that humans and other living things have existed in the present form only.

    * I know there is other research showing white evangelicals have lower income than seculars and that white evangelicals overwhelmingly identify themselves as Republicans while seculars tend to identify themselves as Democrats.

    Taken together this suggests acceptance of natural selection is strongly correlated with income and party affiliation.

    It also suggests there’s been a massive failure of American science education and a triumph for conservative religious ideology.

  6. 6 6 Windypundit

    Arg. As soon as you said the women were put in categories from 1 to 5, I knew there was a problem, because that sounds like only one person rated each woman, which was the case. Surely they should have used a group of raters and computed average scores of some kind?

    Also, as an amateur photographer, I’d be very wary of using photographs of women. The camera sees people very differently from how they appear in real life, and the interaction between photographer and subject will add a lot of variation. (Unless you’re aware of studies which show that photogaphic judgement of beauty correlates well to real-life judgement using ordinary people.)

  7. 7 7 Philip

    I don’t think Kanazawa can be suspected of selective “clumping” of data in a search for statistical significance. Yes, there are multiple way of clumping the data to find statistical significance, but only two for testing Kanazawa’s hypothesis: 5s alone and 4s & 5s together. An since the standard he’s testing is “very attractive” not “more attractive than average” he has only one way to clump the data: 5s alone.

    Moreover, unless things have changed since my graduate school statistics course (and well they may), a > 95% confidence interval is the gold standard for social science research (99% being the platinum standard).

    Since Kanazawa has a theory with which his findings are consistent, I assume that should give us more confidence in his results.

    Certainly, it would’ve been preferable to use a 10-point scale (for one reason, to avoid confusion for the male reseachers when someone says “Wow! She’s a 5!), but the subsamples would have been so small that finding statistical significant would have been very unlikely.

    I like your hypothesis that mothers of young boys are more likely to look more haggarded than mothers of young girls. Very plausible.

  8. 8 8 Fenn

    Gelman was critical of the methods and put the number at a (questionalbe) 8%.

    http://www.stat.columbia.edu/~gelman/blog/

  9. 9 9 dave schutz

    The Mona Lisa, she’s okay. Not a head turner, but okay. I think she was a head-turner then. I’ve seen photos of Ellen Terry. Again, okay, but not crazy-making – now. Clearly, guys went nuts for her then. Emma Goldman – kind of drab. Mata Hari, okay, but not a ten. What I’m driving at is that standards of beauty change drastically in a hundred years, or five hundred. Mauritanian men want women who look grossly fat to us. I can’t see the target – beauty – being stable enough that it could drive evolution for people.

  10. 10 10 Philip

    It occurs to me that Steve’s “haggard” hypothesis operates at a second level. If some women are more likely to produce girls and others are more likely to produce boys (averaging at the aggregate level at about 50/50), the haggard mothers of boys are more likely to delay a second and third round of child-bearing (more likely to produce boys) than the rested mother of girls (more likely to produce girls).

    Since trophy wives are more likely to have live-in nannies from birth, this would aggregerate the difference.

  11. 11 11 AaronG

    @ Phillip,

    Kanazawa’s actual hypothesis is that beauty is more important in reproductive success for women because beauty is a good shortcut for assessing the youth and health of a person. Since the mother’s health and youth are more important than the father’s for successful procreation (eg. she has to be pre-menopausal and survive a pregnancy), men place more weight on beauty in selecting mates. Therefore, ugly women should have a preference for ugly male offspring because they will be less handicapped than ugly female offspring in the reproductive game.

    Kanazawa’s hypothesis would lead one to expect the 1’s in his study to have more male offspring and the 5’s to have more female offspring. This is not the result he got, but by choosing an appropriate subset of the results to present, the study appears to support his thesis.

    Regarding, the 95% confidence, I don’t think Steve is quibbling with whether such results should be publishable (though he might). To mind mind, he is just making the point that the daughter/divorce connection has considerably more evidence supporting it that Kanazawa’s claim about the beauty/daughter connection, even if you concede that kanazawa’s statistics are sound.

  12. 12 12 Bennett Haselton

    The whole argument takes one thing for granted that is commonly assumed but not necessarily supported by data:
    “Beauty is more valuable to girls than it is to boys…”

    According to studies such as this:
    http://findarticles.com/p/articles/mi_qa3717/is_199404/ai_n8726907/
    normally, men will admit to caring about looks more than women will. However, hooking up the subjects to a (phony) polygraph machine causes an increase in the degree to which both men and women admit to caring about looks — and, the women’s answers change by a much larger margin, so that when being polygraphed, women admit to caring about looks even more than men do.

    To me, actually, this has always been rather obvious: The men I’ve known who have been the most popular with women, have been the best-looking ones. But why is the stereotype that men care more about looks?

    I suspect it’s because the nicest-looking men are not the “stereotypically handsome” ones, but the ones who have positive attributes reflected in their faces — the kind of man where people think that they “look kind”, or they “look intelligent”, or they “look confident”. So when I say the most popular guys I know are the best-looking ones, I’m talking about guys with those kinds of looks, not “stereotypically handsome” ones. People see those men attaining popularity, and they attribute it to the properties reflected in their faces, such as being kind and intelligent. Of course, that’s just another form of beauty, and the men may not actually be kind or intelligent.

    Teen comedies often have a supporting role for the stereotypically handsome jock, often as a villain. But the lead role is usually played by a guy who doesn’t “look handsome”, but rather a guy who “looks nice” — guys like Jason Biggs from American Pie, Colin Hanks, or Ben Foster, guys like that.

    What’s the evo bio explanation? Perhaps when women are attracted to “influential” men, what matters is not so much that they’re attracted to men who actually *have* good leadership qualities, but that the men have qualities which *everyone else* will perceive as good leadership qualities. If a certain feature — like a prominent jaw — arbitrarily gets a tiny edge as an “indicator of leadership”, then it becomes a self-fulfilling prophecy — following the leadership of (and having sex with) the guy with the prominent jaw, becomes a winning strategy, if everyone else wants to follow the leadership of the same guy and have sex with your sons who inherit the prominent jaw.

    It may be a stretch, but how else could we have evolved to believe something so silly, as the idea that someone with a prominent jaw is good at organizing followers and making critical decisions?

  13. 13 13 GregS

    I want to cast some skepticism on the argument that goes, “If trait X is more useful to women, the class with trait X should produce more daughters.” In this example, suppose there is at some time an abundance of beautiful women. Wouldn’t it become advantageous to then produce a lot of beautiful sons? Wouldn’t such a population of “beautiful daughter makers” then be infiltrated by a population of “beautiful son makers?” (Assuming that beauty less useful but is still useful in the same way to sons as to daughters.)
    One has to ask what the evolutionarily stable state is; it might still be a 50:50 gender split. I’m trying to apply reasoning from “The Selfish Gene” here. Richard Dawkins points out that elephant seals have a roughly 50:50 gender split, even though females are much more likely to reproduce than males. If most seals started producing predominantly female offspring, then a single mother would gain a tremendous advantage by giving birth to primarily sons. This drives the gender ratio to 50:50, if it ever got away from that. (There isn’t really such a fluctuation of the gender ratio, but a more or less stable equilibrium.)
    Also, suppose people with the “status seeking” gene tend to have more sons, and people with the “beautiful” gene tend to have more daughters (again, assuming we have offspring that are likely to make the best use of our genes). Wouldn’t they tend to pair up and wash out any tendencies toward an unbalanced gender ratio? I suppose you could look at couples who are both beautiful, or who both exhibit status seeking, but I’d think someone with either gene wouldn’t be more than a generation or two from an ancestor with the other gene. To put it in other words, a gene that has a tendency to create more daughters would be very likely paired with a gene that has a tendency to create more sons. It seems to me that any population specializing in female production would be infiltrated by a population specializing in male production.
    (I’m trying to share a thought, not necessarily argue my point. I’m still thinking about this.)

  14. 14 14 Philip

    AaronG–

    An interesting response. Thanks.

    “Kanazawa’s actual hypothesis is that beauty is more important in reproductive success for women because beauty is a good shortcut for assessing the youth and health of a person. Since the mother’s health and youth are more important than the father’s for successful procreation (eg. she has to be pre-menopausal and survive a pregnancy), men place more weight on beauty in selecting mates.”

    Maybe I’m missing it, but I can’t find this hypothesis. Perhaps you could point me to it.

    Here’s what I find:

    “The logic of the generalized Trivers–Willard hypothesis (gTWH) provides one potential explanation for the significantly lower offspring sex ratio among physically attractive respondents and the significantly higher levels of physical attractiveness among women than men. The gTWH posits that parents with any heritable traits which increases the reproductive success of female offspring much
    more than that of male offspring have a lower-than-expected number of sons and a higher-than-expected number of daughters. Physical attractiveness is one highly heritable trait, which disproportionately increases the reproductive success of daughters much more than that of sons. Men in all cultures prefer physically attractive women for both long- and short-term mating, whereas
    women prefer physically attractive men mostly for short-term mating (Buss, 1989; Gangestad and Simpson, 2000; Li and Kenrick, 2006).”

    “Therefore, ugly women should have a preference for ugly male offspring because they will be less handicapped than ugly female offspring in the reproductive game.”

    I don’t understand how this follows and why it’s plausible that any woman (ugly or not) would “have a preference for ugly male offspirng” (wouldn’t they always prefer non-ugly sons?), though I do see why they might prefer an ugly son over an ugly daughter. But either way, I don’t see a mechanism through which this preference could effect actual birth outcomes.

    “To mind mind, he [Steve] is just making the point that the daughter/divorce connection has considerably more evidence supporting it that Kanazawa’s claim about the beauty/daughter connection, even if you concede that kanazawa’s statistics are sound.”

    I agree that the daughter/diverce evidence is stronger due to the larger sample size. But with respect to Kanazawa’s claim, Steve says “But I don’t believe it.” I’m just saying the evidence is not as weak as Steve’s analysis suggests and that Kanazawa’s research is worthy, not only of publication, but also replication by other research.

  15. 15 15 Harold

    “I don’t understand how this follows and why it’s plausible that any woman (ugly or not) would “have a preference for ugly male offspirng” (wouldn’t they always prefer non-ugly sons?), though I do see why they might prefer an ugly son over an ugly daughter.” They have no “choice” about ugly offspring, being ugly themselves. They would prefer non ugly sons, but cannot get them.

    If beauty is such a reproductive benefit, why do we still have ugly people?

  16. 16 16 Philip

    Harold-

    Yes, what I said was that I don’t see a mechanism for how a mother’s preference would have an effect on whether she had an ugly son or not. I certainly understand how the genetics of an ugly mother could effect the birth outcome.

    “If beauty is such a reproductive benefit, why do we still have ugly people?”

    Because there’s a shortage of beauty.

    I think a persuasive explanation for how beautify women have children by ugly men more often than ugly women having children by very attractive men lies in the asymmetry between men’s selection criteria and women’s. Based on research I saw some time ago, men tend to select on the basis of physical experience and emotional connection while women tend to select based on their ability to provide and emotional connection.

  17. 17 17 Steve Landsburg

    Philip:

    Yes, what I said was that I don’t see a mechanism for how a mother’s preference would have an effect on whether she had an ugly son or not.

    With the caveat that I am not an evolutionary biologist, it seems to me that the most plausible mechanism is this: Genetic material that bestows beauty on women would also bestow a tendency to invest more resources in nurturing a female fetus than a male one. That way beautiful women would bring more daughters to term.

    That’s not to say the genes would actively seek to destroy male fetuses, just that it would be marginally less willing to invest valuable resources in keeping them alive.

  18. 18 18 Philip

    Yes, that’s a plausible mechanism. But I think your “haggard” mechanism is better: women who have a propensity to have daughters are less “tired”, have more sex in the first several years after birth, beome pregnant sooner and more times during their child-bearing years, and then have more girls than “haggard” women with a propensity to have sons.

    Maybe this hypothesis could be tested through a random sample of two groups of multiple-child Catholic women (who tend to have more children), one group of mothers who have demonstrated a marked tendency to bear daugthers and another group who tend to have sons. You’d expect daughter-producing mothers to have more children than son-producing mothers, controlled for differences in the length of their active child-bearing years.

  19. 19 19 John Faben

    Philip, I find your explanation hard to stomach. Steve’s “haggard” explanation might make sense for why mothers with sons look less attractive now, but I don’t think it can do any work in explaining evolved traits. Remember what Kanazawa refers to as the Savannah Principle (I’m currently in the process of reading his book… my reading list seems to have a massive overlap with things Steve links to from his blog!): we evolved to live in the ancestral environment. Is it really plausible that raising sons is significantly more work for hunter-gatherers than raising daughters?

  20. 20 20 Steve Landsburg

    GregS: I think it is not inconsistent with a 50/50 gender split for women with genes for feminine beauty to specialize in producing daughters while women with other sorts of genes specialize in producing sons.

  21. 21 21 Philip

    John Faben-

    Well, I’m not trying to explain the role of evolved traits. I suppose I’m offering an alternative, or maybe complementary, hypothesis to explain the tendency for beautiful women to produce more daughters than sons based on differences in *behavior* between beautiful women who have a propensity to have daughters and those who tend to have sons. (Of course, there’s a crucial assumption here: that there are women who tend to produce more daughters and others who tend to produce more sons.)

    I think this difference in behavior over hundreds or thousands of generations could also explain the other phenomenon Kanazawa focuses on: the higher proportion of beautiful women to beautiful men in the general population. Of course, this would require the behavioral differences between beautiful daughter-producing women and beautiful son-producing women to have persisted over a very long period of time. But I suppose it’s plausible that very young sons have always been more of a drain on their mothers than very young daughters have been, leading to the train of consequences I describe in my previois post.

    “Is it really plausible that raising sons is significantly more work for hunter-gatherers than raising daughters?”

    Yes, I think it is plausible that very young sons are enough more of a burden for hunter-gatherer mothers that they could delay subsequent pregnancies for son-producing mothers and therefore reduce their lifetime production of children.

    Another behavioral hypothesis comes to mind: parents from ancestral to modern times might be expected to have a preference for sons, and they continued to have daughters until they had the number of sons they sought (e.g., to assist with the hunt or with vigorous agricultural activites). Daughter-producing women would continue producing daughters for a longer period (in order to produced the desired number of sons) than would son-producing women.

    Of course, this mechanism would account for there being more women than men in the general population, not more beautiful women than beautiful men. To account for the beautiful women/men differential, one also must assume that beautiful women are more likely to pass on their genes than are not-beautiful women.

    This differential might be attributable to the tendency of parents of beautiful girls to be more attached to them and care for them better, with more of them surviving to child-bearing age. Moreover, beautiful ancestral women may be more attractive mates leading them to bear more children than not-beautiful women. This seems reasonable since beautiful ancestral women are likely to mate earlier, and bear more children over their lifetimes, with the healthiest and best providing males which they would naturally attract.

    It occurs to me that we need another assumption to make all this work: there must be a correlation between what our ancestors found beautiful in women and what we do. Hmmm. Maybe.

    Maybe it’s all a stretch but none of the steps in this line of reasoning seems beyond plausibility.

  22. 22 22 Nick Chertock

    One issue needing to be addressed is the situation where you have a pretty lady married to an average looking dude (as in my marriage). In our case, we had a daughter who is even cuter than my wife and of course everyone tells me “Luckily she took after her mom”

    I guess my question is: Should I feel as though I accomplished something by ‘marrying up’ or should I be insulted when the 1,000th person says this. And I might add we’re having ANOTHER little girl in May or so my intuition tells me.

    I don’t make a lot of money so I’m still confused why I was able to ‘marry up’ in the beauty department. I chalk it up to my knowledge of Economic Theory plus some hustle.

  23. 23 23 Tagore Smith

    I’m also favorably predisposed toward evolutionary biology. In fact I probably preface about a third of my comments about human societies with “You must remember that we are primates, and that our society is fundamentally a primate society…”

    That said, this is a field that is as prone to “physics envy” as any. It is a mistake to think that we can divorce economics from our origins as (if you’ll forgive me a slight stretch) monkeys. It is just as much a mistake to think that findings about monkeys necessarily apply to us.

    In the end the world is complicated enough that all we can do is take findings about monkeys into account. If there’s one thing I want to rant about it is the tendency of primate researchers to generalize about human behavior without supporting data, but that’s for another day.

    This sort of study is suggestive, but… that’s all it is.

  24. 24 24 Tagore Smith

    And by the way Kanazawa is a loon. A very smart loon, but a loon.

  25. 25 25 Harold

    ““If beauty is such a reproductive benefit, why do we still have ugly people?”

    Because there’s a shortage of beauty. ”

    But how can there be a shortage of beauty? If it is a more succesful trait, and will out-compete ugliness. Ugliness will die out.

  26. 26 26 Steve Landsburg

    Harold: The idea is that a) beauty is costly to produce (in terms of using energy that could go for other things, like maintaining your organs), b) beauty is less costly to produce if you happen to be particularly healthy, c) therefore, only the healthiest can afford to produce beauty, d) therefore the healthiest *do* produce beauty in order to advertise their healthiness; e) therefore beauty is desired, because of what it advertises.

  27. 27 27 Neil

    I still have trouble getting passed square one–the premise that beauty is more advantagous to females in humans. Wombs, not sperm, are the scarce resource here, so males should be competing (with their beauty/health signals) to occupy them. That is what we see in the rest of the animals–males advertising with bigger tails, more colorful plumage, heavier antlers, etc, to an audience of dowdy females. Why are humans different? Perhaps something to do with monogamy, but are we really all that monogamous? What say you, Tiger Woods?

  28. 28 28 Philip

    Neil-

    Competition in the womb is not the only venue for natural selection to have its way.

    If we assume there are some women with a propensity to have daughters and others who tend to produce sons, then (1) the birth of more females than males (through the “haggard mother” mechanism) and (2) the higher propensity of beautiful daughter-producing girls to survive to child-bearing and to produce more children over their lifetimes, gives us a coherent theory to work with.

    Over hundreds or thousands of generations these factors would result in the observed (1) propensity of beautiful women to have more daughters and (2) the difference in the proportions of beautiful women to beautiful men in the genral population.

  29. 29 29 Philip

    Steve-

    I think the assumption that beauty is more costly to produce (Ha! wouldn’t you expect that from an economist) is doubtful as a mechanism for natural selection. Why would beauty be more costly to produce? That cries out for a hypothesis.

    I think the more plausible explanation is that all women compete for the healthiest and best-provider males (I think there’s some scientific evidence for this), and beauty bestows an advantage in that competition. If men place a higher priority on beauty (I think there’s evidence for this too; perhaps men conflate beauty and healthiness), natural selection would favor the production and survival of beautiful daughters and sons via the healthiness/better-provider genes of the male.

    However, this does not fully explain either of the two observed results Kanazawa explores. That requires a different mechanism such as the “haggard mother” hypothesis combined with the assumption that some mothers tend to produce daughters while others tend to produce sons.

  30. 30 30 jrod

    Do you think that the divorce rate among beautiful people is higher because the are pursued more vigorously? This seems to make sense, people go out of there way to mate with them, regardless of marriage.

  31. 31 31 Michael Metcalf Bishop
  32. 32 32 Philip

    Michael M Bishop-

    Thanks for posting this. Very interesting on several fronts.

    Bottom line re: Kanazawa’s conclusions seems to be that his results are not statistically significant, only suggestive, and there’s only a snow ball’s chance in hell of obtaining a statistically significant result for such potentially small effects regardless of sample size.

    This makes a lot of sense considering that, in this case, evolution working over 30,000+ years could be expected to exhibit only a small effect on current populations, too small to show up in statistical studies.

  33. 33 33 Harold

    The Gelman article is very interesting and understandable. I read it that “underpowered” studies (too small sample number to find small efects) are quite likely to find large, apparently statisitcally significant effects. I am not quite sure how the lay reader is to differentiate between an underpowered study and a small effect, or an appropriate sized study and a large effect.

    My earlier comment about ugliness dying out reflects this. I don’t see where the cost of beauty is, so any effect anything like 26% would select for beauty to such an extent that there would rapidly be no ugly people.

    Perhaps I have answered my question above – if a result seems to be much larger than make sense, suspect the stats.

  34. 34 34 Philip

    Harold-

    I now see your point about the 26% differential and ugly dying out. Over a thousand generations that would certainly have taken place at those rates.

    On the other hand, maybe our ancestors put us to shame in the ugly department and we’re the product of this weeding out process. As the evolutionary biologists say: It’s all relatives.

  35. 35 35 Harold

    Philip, that doesn’t bear thinking about – if I am the culmination of thousands of generations of beauty selection, it must have been really bad to be around in the old days!

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