Predicting The Future With Faces

“Your future will be horrible, but at least it will be short. So there’s that”

The future is always uncertain, at least as far as human (and non-human) knowledge is concerned. This is one reason why some people have difficulty saving or investing money for the future: if you give up rewards today for the promise of rewards tomorrow, that might end up being a bad idea if tomorrow doesn’t come for you (or a different tomorrow than the one you envisioned does). Better to spend that money immediately when it can more reliably bring rewards. The same logic extends to other domains of life, including the social. If you’re going to invest time and energy into a friendship or sexual relationship, you will always run the risk of that investment being misplaced. Friends or partners who betray you or don’t reciprocate your efforts are not usually the ones you want to be investing in the first place. You’d much rather invest that effort into the people who will give you better return.

Consider a specific problem, to help make this clear: human males face a problem when it comes to long-term sexual relationships, which is that female reproductive potential is limited. Not only can women only manage one pregnancy at a time, but they also enter into menopause later in life, reducing their subsequent reproductive output to zero. One solution to this problem is to only seek short-term encountered but, if you happen to be a man looking for a long-term relationship, you’d be doing something adaptive by selecting a mate with the greatest number of years of reproductive potential ahead of her. This could mean selecting a partner who is younger (and thus has the greatest number of likely fertile years ahead of her) and/or selecting one who is liable to enter menopause later.

Solving the first problem – age – is easy enough due to the presence of visual cues associated with development. Women who are too young and do not possess these cues are not viewed as attractive mates (as they are not currently fertile), become more attractive as they mature and enter their fertile years, and then become less attractive over time as fertility (both present and future) declines. Solving the second problem – future years of reproductive potential, or figuring out the age at which a woman will enter menopause – is trickier. It’s not like men have some kind of magic crystal ball they can look into to predict a woman’s future expected age at menopause to maximize their reproductive output. However, women do have faces and, as it turns out, those might actually be the next best tool for the job.

Fred knew it wouldn’t be long before he hit menopause

A recent study by Bovet et al (2017) sought to test whether men might be able to predict a woman’s age at menopause in advance of that event by only seeing her face. One obvious complicating factor with such research is that if you want to assess the extent to which attractiveness around, say, age 25 predicts menopause in the same sample of women, you’re going to have to wait a few decades for them to hit menopause. Thankfully, a work-around exists in that menopause – like most other traits – is partially heritable. Children resemble their partners in many regards, and age of menopause is one of them. This allowed the researchers to use a woman’s mother’s age of menopause as a reasonable proxy for when the daughter would be expected to reach menopause, saving them a lot of waiting. 

Once the participating women’s mother’s age of menopause was assessed, the rest of the study involved taking pictures of the women’s faces (N = 68; average age = 28.4) without any makeup and with as neutral as an expression as possible. These faces were then presented in pairs to male raters (N = 156) who selected which of the two was more attractive (completing that task a total of 30 times each). The likelihood of being selected was regressed against the difference between the mother’s age of menopause for each pair, controlling for facial femininity, age, voice pitch, waist-to-hip ratio, and a value representing the difference between a woman’s actual and perceived age (to ensure that women who looked younger/older than they actually were didn’t throw things off).

A number of expected results showed up, with more feminine faces (ß = 0.4) and women with more feminine vocal pitch (ß = 0.2) being preferred (despite the latter trait not being assessed by the raters). Women who looked older were also less likely to be selected (ß = -0.56) Contrary to predictions, women with more masculine WHRs were preferred (ß = 0.13), even though these were not visible in the photos, suggesting WHR may cue different traits than facial ones. The main effect of interest, however, concerned the menopausal variable. These results showed that as the difference between the pair of women’s mother’s age of menopause increased (i.e., one woman expected to go through menopause later than the other), so too did the probability of the later-menopausal woman getting selected (ß = 0.24). Crucially, there was no correlation between a woman’s expected age of menopause and any of the more-immediate fertility cues, like age, WHR, facial or vocal femininity. Women’s faces seemed to be capturing something unique about expected age at menopause that made them more attractive.

Trading off hot daughters for hot flashes

Now precisely what features were being assessed as more attractive and the nature of their connection to age of menopause is unknown. It is possible – perhaps even likely – that men were assessing some feature like symmetry that primarily signals developmental stability and health, but that variable just so happen to correlate with age at menopause as well (e.g., healthier women go through menopause later as they can more effectively bear the costs of childbearing into later years). Whatever systems were predicting age at menopause might not specifically be designed to do so. While it is possible that some features of a woman’s face uniquely cues people into expected age at menopause more directly without primarily cuing some other trait, that remains to be demonstrated. Nevertheless, the results are an interesting first step in that direction worth thinking about.

References: Bovet, J., Barkat-Defradas, M., Durand, V., Faurie, C., & Raymond, M. (2017). Women’s attractiveness is linked to expected age at menopause. Journal of Evolutionary Biology, doi: 10.1111/jeb.13214

If No One Else Is Around, How Attractive Are You?

There’s anecdote that I’ve heard a few times about a man who goes to a diner for a meal. After finishing his dinner the waitress asks him if he’d like some dessert. When he inquires as to what flavors of pie they have the waitress tells him they have apple and cherry. The man says cherry and the waitress leaves to get it. She returns shortly afterwards and tells him she had forgotten they actually also had a blueberry pie. “In that case,” the man replies, “I’ll have apple.” Breaking this story down into a more abstract form, the man was presented with two options: A and B. Since he prefers A to B, he naturally selected A. However, when represented with A, B, and C, he now appears to reverse his initial preference, favoring B over A. Since he appears to prefer both A and B over C, it seems strange that C would affect his judgment at all, yet here it does. Now that’s just a funny little story, but there does appear some psychological literature suggesting that people’s preferences can be modified in similar ways.

“If only I had some more pointless options to help make my choice clear”

The general phenomenon might not be as strange as it initially sounds for two reasons. First, when choosing between A and B, the two items might be rather difficult to directly compare. Both A and B could have some upsides and downsides, but since they don’t necessarily all fall in the same domains, weighing them against the other isn’t always simple. As a for instance, if you looking to buy a new car, one option might have good gas mileage and great interior features (option A) while the other looks more visually appealing and comes with a lower price tag (option B). Pitting A against B here doesn’t always yield a straightforward choice, but if option C rolls around that gets good gas mileage, looks visually appealing, and comes with a lower price tag, this car can look better than either of the previous options by comparison. This third option need not even better more appealing than both alternatives, however; simply being preferable to one of them is usually enough (Mercier & Sperber, 2011).

Related to this point, people might want to maintain some degree of justifiably in their choices as well. After all, we don’t just make choices in a vacuum; the decisions we make often have wider social ramifications, so making a choice that can be easily justified to others can make them accept your decisions more readily (even if the choice you make is overall worse for you). Sticking with our car example, if you were to select option A, you might be praised by your environmentally-conscience friends while mocked by your friends more concerned with the look of the car; if you choose option B a similar outcome might obtain, but the friends doing the praising and mocking could switch. However, option C might be a crowd pleaser for both groups, yielding a decision with greater approval (you miss out on the interior features you want, but that’s the price you pay for social acceptance). The general logic of this example should extend to a number of different domains both in terms of things you might select and features you might use as the basis to select them on. So long as your decisions need to be justified to others, the individual appeal of certain features can be trumped.

Whether these kinds of comparison effects exist across all domains is an open question, however. The adaptive problems species need to solve often require specific sets of cognitive mechanics, so the mental algorithms that are leveraged to solve problems relating to selecting a car (a rather novel issue at that) might not be the same that help solve other problems. Given that different learning mechanisms appear to underlie seemingly similar problems – like learning the location of food and water - there is some good theoretical reasons to suspect that these kinds of comparison effects might not exist in domains where decisions require less justification, such as selecting a mate. This brings us to the present research today by Tovee et al (2016) who were examining the matter of how attractive people perceive the bodies of others (in this case, women) to be.

“Well, that’s not exactly how the other participants posed, but we can make an exception”

Tovee et al (2016) were interested in finding out whether judging bodies among a large array of other bodies might influence the judgments on any individual body’s attractiveness. The goal here was to find out whether people’s bodies have an attractiveness value independent of the range of bodies they happen to be around, or whether attractiveness judgments are made in relation to immediate circumstances. To put that another way, if you’re a “5-out-of-10″ on your own, might standing next to a three (or several threes) make you look more like a six? This is a matter of clear empirical importance as, when studies of this nature are conducted, it is fairly common for participants to be rating a large number of targets for attractiveness one after the other. If attractiveness judgments are, in some sense, corrupted from previous images there are implications for both past and future research that make use of such methods.

So, to get at the matter, the researchers employed a straightforward strategy: first, they asked one group of 20 participants (10 males and females) to judge 20 images of female bodies for attractiveness (these bodies varied in their BMI and waist-to-hip ratio; all clothing was standardized and all faces blurred out). Following that, a group of 400 participants rated the same images, but this time only rating a single image rather than 20 of them, again providing 10 male and female ratings per picture. The logic of this method is simple: if ratings of attractiveness tend to change contingent on the array of bodies available, then the between-subjects group ratings should be expected to differ in some noticeable way than those of the within-subjects group.

Turning to the results, there was a very strong correspondence between male and female judgments of attractiveness (r = .95) as well as within sex agreement (Cronbach’s alphas of 0.89 and 0.95). People tended to agree that as BMI and WHR increased, the women’s bodies became less attractive (at least within the range of values examined; the results might look different if women with very low BMIs were examined). As it turns out, however, there were no appreciable differences when comparing the within- and between-groups attractiveness ratings. When people were making judgments of just a single picture, they delivered similar judgments to those presented with many bodies. The authors conclude that perceptions of attractiveness appear to be generated by (metaphorically) consulting an internal reference template, rather than such judgments being influenced by the range of available bodies.

Which is not to say that being the best looking member of group will hurt

These findings make quite a bit of sense in light of the job that judgments of physical attractiveness are supposed to accomplish; namely assessing traits like physical health, fertility, strength, and so on. If one is interested in assessing the probable fertility of a given female, that value should not be expected to change as a function of whom she happens to be standing next to. In a simple example, a male copulating with a post-menopausal female should not be expected to achieve anything useful (in the reproductive sense of word), and the fact that she happened to be around women who are even older or less attractive shouldn’t be expected to change that fact. Indeed, on theoretical level we shouldn’t expect the independent attractiveness value of a body to change based on the other bodies around; at least there doesn’t seem to be any obvious adaptive advantages to (incorrectly) perceive a five as a six because she’s around a bunch of threes, rather than just (accurately) perceiving that five as a five and nevertheless concluding she’s the most attractive of the current options. However, if you were to incorrectly perceive that five as a six, it might have some downstream consequences when future options present themselves (such as not pursuing a more attractive alternative because the risk vs. reward calculations are being made with inaccurate information). As usual, acting on accurate information tends to have more benefits that changing your perceptions of the world.

References: Mercier, H. & Sperber, D. (2011). Why do humans reason? Arguments for an argumentative theory. Behavioral and Brain Sciences, 34, 57-111.

Tovee, M., Taylor, J., & Cornelissen, P. (2016). Can we believe judgments of human physical attractiveness? Evolution & Human Behavior, doi: 10.1016/j.evolhumbehav.2016.10.005

Money For Nothing, But The Chicks Aren’t Free

When people see young, attractive women in relationships with older and/or unattractive men, the usual perception that comes to mind is that the relationship revolves around money. This perception is usual because it tends to be accurate: women do, in fact, tend to prefer men who both have access to financial resources and who are willing to share them.  What is rather notable is that the reverse isn’t quite as a common: a young, attractive man shacking up with an older, rich woman just doesn’t call too many examples to mind. Women seem to have a much more pronounced preference for men with wealth than men have for women. While examples of such preferences playing themselves out in real life exist anecdotally, it’s always good to try and showcase their existence empirically.

Early attempts were made by Dr. West, but replications are required

This brings me to a new paper by Arnocky et al (2016) that examined how altruism affects mating success in humans (as this is still psychology research, “humans” translates roughly as “undergraduate psychology majors”, but such is the nature of convenience samples). The researchers first sought (a) to document that more altruistic people really were preferred as mating partners (spoilers: they are), and then (b) to try and explain why we might expect them to be. Let’s begin with what they found, as that much is fairly straightforward. In their first study, Arnocky et al (2016) recruited 192 women and 105 men from a Canadian university and asked them to complete a few self-report measures: an altruism scale (used to measure general dispositions towards providing aid to others when reciprocation is unlikely), a mating success scale (measuring perceptions of how desirable one tends to be towards the opposite sex), their numbers of lifetime sexual partners, as well as the number of those that were short-term, the number of times over the last month they had sex with their current partner (if they had one, which about 40% did), and a measure of their personality more generally.

These measures were then entered into a regression (controlling for personality). When it came to predicting perceived mating success, reported altruism was a significant predictor (ß = 0.25), but neither sex nor the altruism-sex interaction was. This suggests that both men and women tend become more attractive to the opposite sex if they behave more altruistically (or, conversely, that people who are more selfish are less desirable, which sounds quite plausible). However, what it means for one to be successful in the mating domain varies by sex: for men, having more sexual partners usually implies a greater level of success, whereas the same does not hold true for women as often (as gametes are easy to obtain for women, but investment is difficult). In accordance with this point, it was also found that altruism predicted the number of lifetime sexual partners overall (ß = .16), but this effect was specific to men: more altruistic men had more sexual partners (and more casual ones), whereas more altruistic women did not. Finally, within the contexts of existing relationships, altruism also (sort of) predicted the number of times someone had sex with their partner in the last month (ß = .27); while there was not a significant interaction with sex, a visual inspection of the provided graphs suggest that if this effect existed, it was being predominately carried by altruistic women having more sex within a relationship; not the men.

Now that’s all well and good, but the authors wanted to go a little further. In their second study, rather than just asking participants about how altruistic they were, they offered participants the opportunity to be altruistic: after completing the survey, participants could indicate how much (if any) of their earnings they wanted to donate to a charity of their choice. That way, you get what might be a less-biased measure of one’s actual altruism (rather than their own perception of it). Another 335 women and 189 men were recruited for this second phase and, broadly, the results follow the same general pattern, but there were some notable differences. In terms of mating success, actual altruistic donations (categorized as either making a donation or not, rather than the amount donated) were not a good predictor (ß = -.07). In terms of number of lifetime dating and sexual partners, however, the donation-by-sex interaction was significant, indicating that more charitable men – but not women – had a greater number of relationships and sexual partners (perhaps suggesting that charitable men tend to have more, but shorter, relationships, which isn’t necessarily a good thing for the women involved). Donations also failed to predict the amount of sex participants had been having in their relationship in the last month.

Guess the blood drive just isn’t a huge turn on after all

With these results in mind, there are two main points I wanted to draw attention to. The first of these concerns the measures of altruism in general: effectively charitable behaviors to strangers. While such a behavior might be a more “pure” form of altruistic tendencies as compared with, say, helping a friend move or giving money to your child, it does pose some complications for the present topic. Specifically, when looking for a desirable mate, people might not want someone who is just generally altruistic. After all, it doesn’t always do me much good if my committed partner is spending time and investing resources in other people. I would probably prefer that resources be preferentially directed at me and those I care about, rather than strangers, and I might especially dislike it if altruism directed towards strangers came at my expense (as the same resources can’t be invested in me and someone else most of the time). While it is possible that such investments in strangers could return to me later in the form of them reciprocating such aid to my partner, it seems unlikely that deficit would be entirely and consistently made up, let alone surpassed.

To make the point concrete, if someone was equally altruistic towards all people, there would be little point in forming as kind of special relationship with that kind person (friendships or otherwise) because you’d get the same benefits from them regardless of how much you invested in them (even if that amount was nothing).

This brings me to the second point I wanted to discuss: the matter of why people like the company of altruists. There are two explanations that come to mind. The first explanation is simple: people like access to resources, and altruists tend to provide them. This explanation should hardly require much in the way of testing given its truth is plainly obvious. The second explanation is more complex, and it’s one the authors favor: altruism honestly signals some positive, yet difficult-to-observe quality about the altruist. For instance, if I were to donate blood, or my time to clean up a park, this would tell you something about my underlying genetic qualities, as an individual in worse condition couldn’t shoulder the costs of altruism effectively. In this sense, altruism functions in a comparable manner to a peacock’s tail feathers; it’s a biologically-honest signal because it’s costly.

While it does have some plausibility, this signaling explanation runs into some complications. First, as the authors note, women donated more than men did (70% to 57%), despite donating predicting sexual behavior better for men. If women were donating to signal some positive qualities in the mating domain, it’s not at all clear it was working. Further, patterns of charitable donations in the US show a U-shaped distribution, whereby those with access to the most and  the fewest financial resources tend to donate more than those in the middle. This seems like a pattern the signaling explanation should not predict if altruism is meaningfully and consistently tied to important, but difficult-to-observe biological characteristics. Finally, while the argument could be made that altruism directed towards friends, sexual partners, and kin are not necessarily indicative of someone’s willingness to donate to strangers (i.e., how altruistic they are dispositionally might not predict how nepotistic they are), well, that’s kind of a problem for the altruism-as-signaling model. If donations towards strangers are fairly unpredictive of altruism towards closer relations, then they don’t really tell you what you want to know.  Specifically, if you want to know how good of a friend or dating partner someone would be for you, a better cue is how much altruism they direct towards their friends and romantic partners; not how much they direct to strangers.

“My boyfriend is so altruistic, buying drinks for other women like that”

Last, we can consider the matter of why people behave altruistically, with respect to the mating domain. (Very) broadly speaking, there are two primary challenges people need to overcome: attracting a mate and retaining them. Matters get tricky here, as altruism can be used for both of these tasks. As such, a man who is generally altruistic towards lot of people might be using altruism as a means of attracting the attention of prospective mates without necessarily intending to keep them around. Indeed, the previous point about how altruistic men report having more relationships and sexual partners could be interpreted in just such a light. There are other explanations, of course, such as the prospect that generally selfish people simply don’t have many relationships at all, but these need to be separated out. In either case, in terms of how much altruism we provide to others, I suspect that the amount provided to strangers and charitable organizations only makes up a small fraction; we give much more towards friends, family, and lovers regularly. If that’s the case, measuring someone’s willingness to donate in those fairly uncommon contexts might not capture their desirability as partner as well as we would like.

References: Arnocky, S., Piche, T., Albert, G., Ouellette, D., & Barclay, P. (2016). Altruism predicts mating success in humans. British Journal of Psychology, DOI:10.1111/bjop.12208


Smoking Hot

If the view counts on previous posts have been any indication, people really do enjoy reading about, understanding, and – perhaps more importantly – overcoming the obstacles found on the dating terrain; understandably so, given its greater personal relevance to their lives. In the interests of adding some value to the lives of others, then, today I wanted to discuss some research examining the connection between recreational drug use and sexual behavior in order to see if any practical behavioral advice can be derived from it. The first order of business will be to try and understand the relationship between recreational drugs and mating from an evolutionary perspective; the second will be to take a more direct look at whether drug use has positive and negative effects when it comes to attracting a partner, and in what contexts those effects might exist. In short, will things like drinking and smoking make you smoking hot to others?

So far selling out has been unsuccessful, so let’s try talking sex

We can begin by considering why people care so much about recreational drug use in general: from historical prohibitions on alcohol to modern laws prohibiting the possession, use, and sale of drugs, many people express a deep concern over who gets to put what into their body at what times and for what reasons. The ostensibly obvious reason for this concern that most people will raise immediately is that such laws are designed to save people from themselves: drugs can cause a great degree of harm to users and people are, essentially, too stupid to figure out what’s really good for them. While perceptions of harm to drug users themselves no doubt play a role in these intuitions, they are unlikely to actually be whole story for a number of reasons, chief among which is that they would have a hard time explaining the connection between sexual strategies and drug use (and that putting people in jail probably isn’t all that good for them either, but that’s another matter). Sexual strategies, in this case, refer roughly to an individual’s degree of promiscuity: some people preferentially enjoy engaging in one or more short-term sexual relationships (where investment is often funneled to mating efforts), while others are more inclined towards single, long-term ones (where investment is funneled to parental efforts). While people do engage in varying degrees of both at times, the distinction captures the general idea well enough. Now, if one is the type who prefers long-term relationships, it might benefit you to condemn behaviors that encourage promiscuity; it doesn’t help your relationship stability to have lots of people around who might try to lure your mate away or reduce the confidence of a man’s paternity in his children. To the extent that recreational drug use does that (e.g., those who go out drinking in the hopes of hooking up with others owing to their reduced inhibitions), it will be condemned by the more long-term maters in turn. Conversely, those who favor promiscuity should be more permissive towards drug use as it makes enacting their preferred strategy easier.

This is precisely the pattern of results that Quintelier et al (2013) report: in a cross-cultural sample of Belgians (N = 476), Dutch (N = 298), and Japanese (N = 296) college students who did not have children, even after controlling for age, sex, personality variables, political ideology, and religiosity, attitudes towards drug use were still reliably predicted by participant’s sexual attitudes: the more sexually permissive one was, the more they tended to approve of drug use. In fact, sexual attitudes were the best predictors of people’s feelings about recreational drugs both before and after the controls were added (findings which replicated a previous US sample). By contrast, while the non-sexual variables were sometimes significant predictors of drug views after controlling for sexual attitudes, they were not as reliable and their effects were not as large. This pattern of results, then, should yield some useful predictions about how drug use effects your attractiveness to other people: those who are looking for short-term sexual encounters might find drug use more appealing (or at least less off-putting), relative to those looking for long-term relationships.

“I pronounce you man and wife. Now it’s time to all get high”

Thankfully, I happen to have a paper on hand that speaks to the matter somewhat more directly. Vincke (2016) sought to examine how attractive brief behavioral descriptions of men were rated as being by women for either short- or long-term relationships. Of interest, these descriptions included the fact that the man in question either (a) did not, (b) occasionally, or (c) frequently smoke cigarettes or drink alcohol. A sample of 240 Dutch women were recruited and asked to rate these profiles with respect to how attractive the men in question would be for either a casual or committed relationship and whether they thought the men themselves were more likely to be interested in short/long-term relationships.

Taking these in reverse order, the women rated the men who never smoked as somewhat less sexually permissive (M = 4.31, scale from 1 to 7) than those who either occasionally or frequently did (Ms = 4.83 and 4.98, respectively; these two values did not significantly differ). By contrast, those who never drank or occasionally did were rated as being comparably less permissive (Ms = 4.04) than the men who drank frequently (M = 5.17). Drug use, then, did effect women’s perceptions of men’s sexual interests (and those perceptions happen to match reality, as a second  study with men confirmed). If you’re interested in managing what other people think your relationship intentions are, then, managing your drug use accordingly can make something of a difference. Whether that ended up making the men more attractive is a different matter, however.

As it turns out, smoking and drinking appear to look distinct in that regard: in general, smoking tended to make men look less attractive, regardless of whether the mating context was short- or long-term, and frequent smoking was worse than occasional smoking. However, the decline in attractiveness from smoking was not as large in short-term contexts. (Oddly, Vincke (2016) frames smoking as being an attractiveness benefit in short-term contexts within her discussion when it’s really just less of a cost. The slight bump seen in the data is neither statistically or practically significant) This pattern can be seen in the left half of the author’s graph. By contrast – on the right side – occasional drinkers were generally rated as more attractive than men who never or frequently drank across conditions across both short- and long-term relationships. However, in the context of short-term mating, frequent drinking was rated as being more attractive than never drinking, whereas this pattern reversed itself for long-term relationships. As such, if you’re looking to attract someone for a serious relationship, you probably won’t be impressing them much with your ability to do keg stands of liquor, but if you’re looking for someone to hook up with that night it might be better to show that off than sip on water all evening.

Cigarettes and alcohol look different from one another in the attractiveness domain even though both might be considered recreational drug use. It is probable that what differentiates them here is their effects on encouraging promiscuity, as previously discussed. While people are often motivated to go out drinking in order to get intoxicated, lose their inhibitions, and have sex, the same cannot usually be said about smoking cigarettes. Singles don’t usually congregate at smoking bars to meet people and start relationships, short-term or otherwise (forgoing for the moment that smoking bars aren’t usually things, unless you count the rare hookah lounges). Smoking might thus make men appear to be more interested in casual encounters because it cues a more general interest in short-term rewards, rather than anything specifically sexual; in this case, if one is willing to risk the adverse health effects in the future for the pleasure cigarettes provide today, then it is unlikely that someone would be risk averse in other areas of their life.

If you want to examine sex specifically, you might have picked the wrong smoke

There are some limitations here, namely that this study did not separate women in terms of what they were personally seeking in terms of relationships or their own interests/behaviors when it comes to engaging in recreational drug use. Perhaps these results would look different if you were to account for women’s smoking/drinking habits. Even if frequent drinking is a bad thing for long-term attractiveness in general, a mismatch with the particular person you’re looking to date might be worse. It is also possible that a different pattern might emerge if men were assessing women’s attractiveness, but what differences those would be are speculative. It is unfortunate that the intuitions of the other gender didn’t appear to be assessed. I think this is a function of Vincke (2016) looking for confirmatory evidence for her hypothesis that recreational drug use is attractive to women in short-term contexts because it entails risk, and women value risk-taking more in short-term male partners than long-term ones. (There is a point to make about that theory as well: while some risky activities might indeed be more attractive to women in short-term contexts, I suspect those activities are not preferred because they’re risky per se, but rather because the risks send some important cue about the mate quality of the risk taker. Also, I suspect the risks need to have some kind of payoff; I don’t think women prefer men who take risks and fail. Anyone can smoke, and smoking itself doesn’t seem to send any honest signal of quality on the part of the smoker.)

In sum, the usefulness of these results for making any decisions in the dating world is probably at its peak when you don’t really know much about the person you’re about to meet. If you’re a man and you’re meeting a woman who you know almost nothing about, this information might come in handy; on the other hand, if you have information about that woman’s preferences as an individual, it’s probably better to use that instead of the overall trends. 

References: Quintelier, K., Ishii, K., Weeden, J., Kurzban, R., & Braeckman, J. (2013). Individual differences in reproductive strategy are related to views about recreational drug use in Belgium, the Netherlands, and Japan. Human Nature, 24, 196-217.

Vincke, E. (2016). The young male cigarette and alcohol syndrome: Smoking and drinking as a short-term mating strategy. Evolutionary Psychology, 1-13.

Understanding Male Investment In Children

As a rather social species, humans seem to have a fairly advanced theory of mind. By that, I mean we attribute things like beliefs, intentions, desires, and so on to other people in efforts to understand, explain, predict, and manipulate the behavior of others. The adaptive value of this skill can be hard to overstate and, accordingly, we ought to expect people to be pretty accurate at figuring out the mental states of others. That said, doing so with perfect accuracy is not an easy task, despite our general proficiency with it. Part of the reason, of course, is that things like beliefs and desires are not themselves directly observable, requiring us to make certain assumptions about the reasons for the observable behavior of others. Another part of the reason, however, is that people often have a vested interest in convincing others about certain internal states of affairs, and that interest persists even in the absence of truth value. For instance, if my suffering tends to draw investment from others in the form of social or material resources, it might pay for some cognitive mechanism of mine to over-represent how much I am suffering publicly to others.

“No, really; I am in that much pain. Just come a little closer and see…”

As an example of the trickier aspects of figuring out the intentions and motivations of others, I wanted to use a case of paternal investment in humans. In many mammalian species, males do not tend to assist in the raising of offspring at all. This is owing largely to the fact that males cannot be assured of their paternity the way females can “know” the child they give birth to is theirs. Human males, by stark contrast, often offer substantial investment in children. However it came about, males in our species managed to largely solve the adaptive problem of paternity uncertainty. The key word in that last sentence, though, is largely: we still can’t be sure that a child is ours 100%, so we might expect that, in general, men are less interested in investing in children than women tend to be, especially if the specter to infidelity has been raised. We might also expect that outcome to obtain owing to opportunity costs; what else we could be doing with the time spent investing in children. Time and energy that I spend investing in raising a child is often time and energy I can’t spend doing other adaptive things, like pursuing additional mating opportunities. As the obligate costs to reproduction are lower for men than women, we might also expect men are more interested in putting their time into pursuing mating opportunities and less interested in putting into investment in children, relative to women.

Now these are theoretically-sound evolutionary reasons for expecting the sex with less obligate investment and genetic certainty (typically males) to be less interested in parenting efforts. The logic of managing these adaptive problems should be instantiated in the psychologies of men and women, and to the extent that men and women face different problems, we should perceive the world and behave in different ways. However, some people don’t like the idea that there is any difference between men and women with respect to how interested they are in raising children. As an example, I would offer this article over at Patheos calling Sam Harris a sexist for suggesting men and women have some different interests when it comes to raising children. In it, the author puts forth two hypotheses: that women being the ones to disproportionately cut their careers short to raise children is due to either “…biology or sexism“. In this case, the author favors the “sexism” explanation which, I think, is that men and women and psychologically indistinguishable with respect to their interest in raising children, and would be just as likely to do so were it not for whatever culture is setting different standards. The author’s theory of mind, then, says that men are just as interested in raising children as women (or at least that’s what one part of her mind says publicly). The notable quote I would consider to outline this hypothesis is, “There is no biological reason men and women cannot share the responsibility of childrearing“. No biological reason making such an outcome impossible, sure; just that a host of them make an equitable distribution of interest in doing so fairly unlikely.

The piece and subsequent comments sections are full of anecdotes about how people know men who are supremely nurturing towards children. I don’t doubt that’s the case, just like I don’t doubt that there are some women who are taller than most men. Variance is a thing, after all, and males in our species do tend to invest in children. It doesn’t follow, though, that there are no aggregate differences in desire rear children between the sexes owing to more than sexist culture. The important thing worth noting here is that desires to invest in children are being inferred from the behavior of investing. The problem with doing so is that people might enact behavior for reasons other than desiring to enact the behavior itself. An easy example is a man visiting a prostitute: just because the man gives the prostitute money, it does not mean his motives are altruistic; he is giving her money instrumentally. If he didn’t have to give her money for the sex, he probably wouldn’t. That sounds simple, I’m sure, but how about the hypothesis that men invest in child rearing for reasons owing to mating effort, rather than parenting effort?

“HA; Got one! Bring on the ladies!”

This brings me to a paper by Anderson, Kaplan, & Lancaster (1999). Now this study doesn’t speak to the matter of sex differences in interest in children, as it only focuses on male behavior, but it makes the point well that inferring motives from behavior can be a problem. The study examined male investment in children in conjunction with their relationship status with the child’s mother. There were four groups the men were placed into: (1) those who had genetic children and were in a relationship with the mother, (2) those who had genetic children and were not in a relationship with the mother, (3) those who had stepchildren with a woman they were in a relationship with, and (4) those who had stepchildren from a past relationship. The researchers had a sample of approximately 1,300 men with offspring in one or more of those categories. The question at hand was whether or not a male’s investment in said children varied as a function of the male’s relationship status with the child’s mother and the children themselves. The male’s investment was considered in four groups: (1) Time spent with the child, (2) money spent on the child, (3) whether the child attended college, and (4) how much support the child received for college.

I want to focus on the monetary investment category, as I feel it’s the easiest to think about, (and because all four classes of investment showed basically the same pattern). With respect to monetary investments over the past year to children 17 or younger, genetic children from a previous relationship received, on average, about $700 less than similarly-aged genetic children from the current relationship (less, in this case, refers to how much a statistical model accounting for a number of factors predicted the typical child should get). By contrast, stepchildren from the current relationship received only around $150 less than genetic children from a current relationship.Stepchildren from a previous relationship received about $1,500 less than genetic children from the current relationship, and $900 less than genetic children from previous relationships. For children age 18-24, the same pattern held, with the exception of the genetic children from past marriages receiving more money than stepchildren from the current one, though the two categories did not differ significantly.

These results found that men do indeed tend to invest in children; often substantial amounts. This fact was never in question. However, the amount they invested in the child, whether in terms of time or money, varied contingent on their genetic relatedness to the child and relationship with the child’s mother. Some of men’s interest in investing in children, like women’s, owes to their relatedness to the child: genetic children from past relationships received much more investment than stepchildren from past relationship. This is classic kin selection. I presume very few people would suggest that parents tend to invest in their own children more because “their culture tells them to do so”, rather than positing some kind of biologically-grounded reason. It also seems like a hefty portion of the investment in children by men could reflect mating effort towards the mother: the men behaved as if they were trying to build or maintain a relationship with a woman through investing in her children. Sure; it might not be as romantic as a dinner date, but investment is investment. It follows that men might well be less interested in raising children per se, but quite interested in maintaining a relationship with the mother, so they invest at certain levels despite their lack of intrinsic interest. Put another way, it is quite plausible that women with children do not generally wish to be in relationships with partners that abuse or neglect the child, so men try to avoid that in order to not be ruled out as mates.


Now, again, I don’t have comparable data for women, but the point at hand is that just because you find men investing in children, it doesn’t mean that their sole motivation is in the investing per se. We could very well find that men and women invested relatively equally (or unequally) in children and that their motives for doing so differ substantially. It is also possible that the people agreeing with the sentiments expressed in the Patheos article represent something of a biased sample, insomuch as they don’t know many men who dislike taking care of children because they wouldn’t want to (and purposefully don’t) associate with such men in the first place. At the very least, I doubt any of them are giving fathers who ran out on their children pats on the back and telling them they understand. Finally, it is also possible that people might be inferring certain motivations on the part of one sex or the other in hopes of convincing people of some particular political viewpoint or to affect a change in their behavior. Though I don’t have much time to speculate about it, if people have a vested interest in seeing sexism as being responsible for a difference between men and women, you can bet they will find it. Similarly, psychological researchers often have a vested interest in finding certain statistical results and, lo and behold, they tend to find them too. If you’d like to speculate more about men and women’s interest in raising children, sexist biases, and the like, I’ll leave you with some helpful places to do just that.

References: Anderson, K., Kaplan, H., & Lancaster, J. (1999). Paternal care by genetic fathers and stepfathers I: Reports from Albuquerque men. Evolution & Human Behavior, 20, 405-431.

In The World Of The Blind, The Woman With A Low WHR Is Queen

If you happen to have memories of watching TV in the 90s, chances are you might remember the old advertisements they used to run for the Cinnamon Toast Crunch cereal. The general premise of the ads followed the same formula: “Person X is really good at seeing Y, but can they see why kids love the taste of Cinnamon Toast Crunch?”. Inevitably, the answer was always “no”, as adults are apparently so square that they couldn’t wrap their minds around the idea that children happen to like sugar. Difficult concept, I know. Now, obviously, adults aren’t nearly so clueless in reality. In fact, as you’re about to see, even adults who are really rather poor at seeing things can still “see”, so to speak, why men tend to find certain features in women attractive.

Sauron majored in sociology, so he guessed “cultural conditioning”

The first paper up for consideration is a 2010 piece by Karremans et al. The researchers begin by noting that men appear to demonstrate a preference for women with relatively-low waist-to-hip ratios (WHRs). Women with low WHRs tend to have figures that resemble the classic hourglass shape. Low WHRs are thought to be found attractive by men because they are cues to a woman’s fertility status: specifically, women with lower WHRs – around a 0.7 – tend to be more fertile than their more tubular-shaped peers. That said, this preference – just like any of our preferences – does not magically appear in our minds; every preference needs to develop over our lives, and development requires particular input conditions. If these developmental input conditions aren’t met, then the preference should not be expected to form. Simple enough. The question of interest, then, is what precisely these conditions are; what factors are responsible for men finding low WHRs attractive?

One ostensibly obvious condition for the development of a preference for low WHRs might be visual input. After all, if men couldn’t see women’s WHRs – and all those unrealistic expectations of female body type set by the nefarious media – it might seem awfully difficult to develop a taste for them. This poses something of an empirical hurdle to test, as most men have the ability to see, Thankfully for psychological research – though not so thankfully for the subjects of that research – some men, for whatever reasons, happen to have been born blind. If visual input was a key condition for the development of preferences for low WHRs in women, then these blind men should not be expected to show it. While large samples of congenitally blind men are not the easiest to come by, Karremans et al (2010) managed to recruit around 20 of them.

These blind men were presented with two female mannequins wearing tight-fitting dresses. One of these mannequins had a WHR of 0.7 – around what most people rate as the most attractive – and the other had a slightly-higher 0.84. The blind men were asked to feel and rate each mannequins on attractiveness from 1 to 10. Additionally, the researchers recruited about 40 sighted men to complete the task as well: 20 completing it while blindfolded and 20 without the blindfold. Of note is that all data collection was carried out in a van (read: “mobile laboratory room”) because sometimes psychological research is just fun like that.

“How about coming into my van to feel my mannequins?”

The first set of results to consider come from the sighted men, who completed the task with the full use of their eyes: they gave the mannequin with the low WHR a rating of around an 8, whereas the mannequin with the higher WHR received only around a 6.5, as one might expect. In the blindfold condition, this difference was reduced somewhat (with ratings of 7.5 and around 7, respectively), suggesting that visual input might play some role in determining this preference. However, visual input was clearly not necessary: the blind men rated the low WHR mannequin at around a 7, but the high WHR mannequin at about a 6. In the words of the fine people over at Cinnamon Toast Crunch: “even blind men who can’t see much of anything can still see why men love the figures of women with low WHRs”.

Further evidence from earlier research points towards a similar conclusion (that these preferences are unlikely to be the result of portrayals of women in the media). A paper by Singh (1993) analyzed a trove of data on the female bodies that appeared in Playboy as centerfolds (from 1955-1965 and 1976-1990) and that won Miss America pageants (1923-1987). One might imagine that depictions of women in the media or found to be attractive might change somewhat over six decades if the type of women being portrayed were favored for some arbitrary set of reasons. Indeed, there was one noticeable trend: the centerfolds and pageant winners tended to be getting a little bit skinnier over that time period. Despite these changes in overall BMI, however, the WHR of the groups didn’t vary. Both grounds hovered around a consistent 0.7. Presumably, if blind men were consuming pornography, they would prefer the women depicted in Playboy just as much as non-blind men do.

“We’ll be needing more “databases” for the mobile laboratory room…”

Given the correlation between WHR and fertility, this consistency in men’s preferences should be expected. That’s not to say, of course, that these preferences for low WHR aren’t modifiable. As I mentioned before, every preference needs to develop, and to the extent that certain modifications of that preference would be adaptive in different contexts, we should expect it to fluctuate accordingly. Now that matter of precisely what input conditions are responsible for the development of this preference remain shrouded: while visual inputs don’t seem to be necessary, the matter of which cues are – as well as why they are – are questions that have yet to be answered. For what it’s worth, I would recommend turning research away from the idea that the media is responsible for just about everything, but that’s just me.

References: Karremans, J., Frankenhuis, W., & Arons S. (2010). Blind men prefer a low waist-to-hip ratio. Evolution and Human Behavior, 31, 182-186.

Singh, D. (1993). Adaptive significance of female physical attractiveness: Role of waist to hip ratio. Journal of Personality and Social Psychology, 65, 293-307.

What Does Online Dating Tell Us About Racial Views?

Preferences can be funny things, or at least our judgments of them. If I were to state that, “I have no interest in hiring a black person to do this job”, I would receive more than a little condemnation for that view. If I were to state instead that, “I have have no interesting in dating a black woman”, I would likely still receive some condemnation, but probably less than for the first statement. Finally, if I were to state that, “I have no interest in dating a man”, I would receive very little, if any, condemnation for it, even from those who advocate strongly for gay rights. As one of my colleagues recently posed the question, “Why is discrimination based on reproductive / sexual preferences OK, but other forms of discrimination are not?” The issue of discrimination is one I’ve discussed before, considering why discrimination on the basis of standardized test scores is deemed to be appropriate, whereas discrimination of the basis of obesity is often not. So let’s turn our attention towards discrimination in the sexual realm today.

“Free?! I’d have to be an idiot not to find the Asian of my dreams!”

A recent post by Jenny Davis over at the Pacific Standard suggests that “Online dating shows us the cold, hard facts about race in America“. In her article, Jenny discusses some data released from a Facebook-based dating app that figures out which people are interested in which other people on some sexual or romantic level. The data is labeled “unfortunate” in some respects, because there appear to be winners and losers, and those winners and losers seem to break down along racial lines. When it comes to mating, it seems that everyone doesn’t get to join hands and cross the finish line at the same time so that we all end up with equally-high self-esteem (I know; I was shocked too).  To give you a sense for the data (and so you don’t have to click back and forth between links), here’s the breakdown of the response rates for people who are interested.

As anyone can clearly see, there are favorites. When it comes to the highest positive response rate, most women, regardless of their race, appear to favor white men, whereas most men, again, regardless of their race, tend to favor Asian women. In terms of the lowest response rate, women appeared to shun black men, whereas men tended to shun black women. Ouch. Jenny, using what I can only assume is that same “high-powered sociological lens” I’ve encountered before, concludes that this clearly demonstrates that race matters, and serves to counter accusations that we are living in a color-blind, post-racial world. As Jenny puts it we “fetishize Asian women while devaluing blacks”. Now tone doesn’t come across well through text-based communications at time, but neither “fetishize” nor “devalue” sound as if they have a particularly positive connotation to me. It sounds as if she’s condemning other people for their sexual preferences in that respect.

There are many comments to make about this, but let’s start with this one: apparently, there’s something of a no-win situation being erected from the get go. When one group is preferred, it’s a “fetish”, whereas when they’re not preferred, they’re “devalued”. Well, sort of, anyway; if she were being consistent (and who is?) Jenny would also say that women “fetishize” white males. Strangely, she does not. One can only guess as to why she does not, because Jenny makes no apparent attempt to understand the data in question. By that, I mean that Jenny offers no potential alternative explanations through which we might understand the data. In fact, she doesn’t seem to offer any explanation whatsoever for these patterns of responses. If I had to, I would guess that her explanation, if simplified somewhat, would reduce to “racism did it”, but it’s hard to tell.

“But are they the Black singles of my dreams, like the Asians?”

I would like to try and pick up some of that explanatory slack. Despite initial appearances, it is possible that this data has very little, if anything, to do with race per se. Now I happen to think that race likely does matter to some extent when it comes to dating preferences, but the degree of that extent is anyone’s guess. To see why I would say this only requires that one understands a very basic statistical concept: correlation does not equal causation. This is something that I imagine Jenny understands, but it likely slipped her mind in the midst of trying to make a point. There are few examples to consider, but the first is by far the simplest. Most men, if you polled them, would overwhelming respond to women on dating websites, and not other men; women would likely do the reserve. This does not mean, however, that men (or women) “devalue” other men (or women). Similarly, just because people on these dating sites might respond to black people at the lowest rates, it does not mean they “devalue” black people more generally.

But maybe we do devalue certain racial groups, at least when it comes to dating them. This brings us to the second issue: mating decisions are often complex. There are dozens of potential variables that people assess when choosing a mate – such as how much money they have, how much they weigh, how tall they are, their age, their relatedness to us, etc – and the importance of these qualities also varies somewhat depending on the nature of the relationship (whether it is more short- or long-term, for instance). The important point here is that even if people are picking mates on the basis of these other characteristics alone and not race, we might still see racial differences in outcomes. Let’s say, for instance, that men tend to prefer women shorter than themselves as dating partners (the reasons for this preference or it’s actual existence need not necessarily concern us). If that were the case, provided there are any average differences in height among the races, we would still see different response rates to and from each racial group, even though no one was selecting on the basis of race.

Rather than just considering the direction the preferences in the data above, then, let’s consider some of the actual numbers: when it came to response rates, regardless of whether we were considering men or women, and regardless of whether we’re considering the highest or lowest response rates, black individuals seem to respond more often than any other group; sometimes around twice as often. This could be indicative of a number of different factors, though I won’t speculate as to which ones on the basis of the numbers alone. The only point is that those factors might show up in user’s profiles in some way. If other people pick up on those factors primarily, then race itself might not be the primary, or even a, factor driving these decisions. In fact, in terms of response rates, there was a consistent overall pattern: from lowest to highest, it tended to be Latinos, Whites, Asians, and Blacks, regardless of sex (with only a single exception). Whatever the reasons for this, I would guess that it shows up in other ways in the profiles of these senders and responders.

Strangely, I can’t find a picture of a white dating site. Odd…

As I said, I don’t think that race per se is entirely unrelated to mating choices. However, to determine the extent to which it uniquely predicts anything, you need to control for other relevant factors. Does obesity play a role in these decisions? Probably. Is obesity equally common across racial groups? Nope. How about income; does income matter? In some cases it sure seems to. Is income the same across racial groups? Nope. We would likely find the same for many, many other factors.

In addition to determining the extent of how much race matters, one might also wish to explain why race might matter. Simply noting that there appear to be some racial differences doesn’t tell us a whole lot; the same goes for correlations of match percentages and response rates over at OkCupid, which find a similar pattern with respect to race. In the instance of OkCupid, a match percentage of 10% between two people corresponds to about a 25% reply rate; a 90% match percentage gets you all the way up to… a 37% reply rate. Even at around 100% match, the response rate still only lingers at around 50%. There appears to be a lot more that goes into mating decisions than people typically appreciate or even recognize. For what it’s worth, I would rather work to understand those complexities than pat myself on the back for how bad I think racism is.

Mathematical Modeling Of Menopause

Some states of affairs are so ubiquitous in the natural world that – much like the air we breathe – we stop noticing their existence or finding them particularly strange. The effects of aging are good examples of this. All else being equal, we ought to expect organisms that are alive longer to reproduce more. The longevity/reproduction link would seem to make the previously-unappreciated question of why organism’s bodies tend to breakdown over time rather salient. Why do organisms grow old and frail, before one or more homeostatic systems start failing, if being alive tends to aid in reproduction? One candidate explanation for understanding senescence involves.considering the trade off between the certainty of the present and the uncertainty of the future; what we might consider the discount rate of life. Each day, our bodies need to avoid death from a variety of sources, such as accidental injuries, intentional injuries from predators or conspecifics, the billions of hungry microorganisms we encounter, or lacking access to sufficient metabolic resources. Despite the whole world seemingly trying to kill us constantly, our bodies manage to successfully cheat death pretty well, all things considered.

“What do we say to death? Not to..OH MY GOD, WHAT’S BEHIND YOU?”

Of course, we don’t always manage to avoid dying: we get sick, we get into fights, and sometimes we jump out of airplanes for fun. Each new day, then, brings new opportunities that might result in the less-than-desirable outcome, and the future is full of new days. This makes each day in the future that much less valuable than each day in the present, as future days come with the same potential benefits, but all the collective added risk. Given the uncertainty of the future, it follows that some adaptations might be designed to increase our chances of being alive today, even if they decrease our odds of being alive tomorrow. These adaptations may well explain why we age the way we do. They would be expected to make us age in very specific ways, though: all our biological systems ought to be expected to breakdown at roughly the same time. This is because investing tons of energy into making a liver that never breaks doesn’t make much sense if the lungs give out too easily, as the body with the well-functioning liver would die all the same without the ability to breathe; better to divert some of that energy from liver maintenance to lung function.

As noted previously, however, being alive is only useful from an evolutionary perspective if being alive means better genetic representation in the future. The most straightforward way of achieving said genetic representation is through direct reproduction. This makes human menopause a very strange phenomenon indeed. Why do female’s reproductive capabilities shut off decades before the rest of their body tends to? It seems that pattern of loss of function parallels the liver/lungs example. Further, as the use of the word ‘human’ suggests, this cessation of reproductive abilities is not well-documented among other species. It’s not that other species don’t ever lose the capacity for reproduction, mind you, just that they tend to lose it much closer to the point when they would die anyway. This adds a second part to our initial question concerning the existence of menopause: why does it seem to only really happen in humans?

Currently, the most viable explanation is known as “The Grandmother Hypothesis“. The hypothesis suggests that, due to the highly-dependent nature of human offspring and the risks involved in pregnancy, it became adaptive for women to cease focusing on producing new offspring of their own and shift their efforts towards investing in their existing offspring and grandoffspring. At its core, the grandmother hypothesis is just an extension of kin selection: the benefits to helping relatives begin to exceed the benefits of direct reproduction. While this hypothesis may well prove to not be the full story, it does have two major considerations going for it: first, it explains the loss of reproductive capacity through a tradeoff – time spent investing in new offspring is time not spent investing in existing ones. It doesn’t commit what I would call the “dire straits fallacy” by trying to get something for free, as some standard psychology ideas (like depressive realism) seem to. The second distinct benefit of this hypothesis is perhaps more vital, however: it explains why menopause appears to be rather human-specific by referencing something unique to humans – extremely altricial infants that are risky to give birth to.

A fairly accurate way to conceptualize the costs of the pregnancy-through-college years.

A new (and brief) paper by Morton, Stone, & Singh (2013) sought to examine another possible explanation for menopause: mate choice on the part of males.The authors used mathematical models to attempt and demonstrate that, assuming men have a preference for young mates, mutations that had deleterious effects on women’s fertility later in life could drift into fixation. Though the authors aren’t explicit on this point, they seem to be assuming, de facto, that human female menopause is a byproduct of senescence plus a male sexual preference for younger women, as without this male sexual preference, their simulated models failed to result in female menopause. They feel their models demonstrate that you don’t necessarily need something like a grandmother hypothesis to explain menopause. My trust in results derived from mathematical models like these can be described as skeptical at the best of times, so it should come as no surprise that I found this explanation lacking on three rather major fronts.

My first complaint is that while their model might show that – given certain states of affairs held – explanations like the grandmother hypothesis need not be necessary, they fail to rule out the grandmother hypothesis in empirical or theoretical way. They don’t bother to demonstrate that their state of affairs actually held. Why that’s a problem is easy to recognize: it would be trivial to concoct a separate mathematical model that “demonstrated” the strength of the grandmother hypothesis by making a different set of assumptions (such as by assuming that past a certain age, investments returned in existing offspring outweighed investments in new ones). Yes; to do so would be pure question-begging, and I fail to see how the initial model provided by Morton et al (2013) isn’t doing just that.

My second complaint is, like the grandmother hypothesis, Morton et al’s (2013) byproduct model does consider tradeoffs, avoiding the dire straits fallacy; unlike the grandmother hypothesis, however, the byproduct account fails to posit anything human-specific about menopause. It seems to me that the explanation on offer from the byproduct account could be applied to any sexually-reproducing species. Trying to explain a relatively human-specific trait with a non-human-specific selection pressure isn’t as theoretically-sound as I would like. “But”, Morton et al might object, “we do posit a human-specific trait: a male preference for young female mates“. A fine rebuttal, complicated only by the fact that this is actually the weakest point of the paper. The authors appear to be trying to use an unexplained-preference to explain the decline in fertility, when it seems the explanation ought to run in precisely the opposite direction. If, as the model initially assumes, ancestral females did not differ substantially in their fertility with respect to age, how would a male preference for younger females ever come to exist in the first place? What benefits would arise to men who shunned older – but equally fertile – women in favor of younger ones? It’s hard to say. By contrast, if our starting point is that older females were less fertile, a preference for younger ones is easily explained.

No amount of math makes this an advisable idea.

Preferences are not explanations themselves; they require explanations. Much like aging, however, people can take preferences for granted because of how common they are (like the human male’s tendency to find females of certain ages maximally attractive), forgetting that basic fact in the process. The demonstration that male mating preferences could have been the driving force explaining the existence of menopause, then, seems empty. The model, like many others that I’ve encountered, seems to do little more than restate the author’s initial assumptions as conclusions, just in the language of math, rather than English. As far as I can see, the model makes no testable or novel predictions, and only manages to reach that point by assuming a maladaptive, stable preference on the part of men. I wouldn’t mark it down as a strong contender for helping us understand the mystery of menopause.

References: Morton, R., Stone, J., & Singh, R. (2013). Mate Choice and the Origin of Menopause PLoS Computational Biology, 9 (6) DOI: 10.1371/journal.pcbi.1003092

Tropes Against Video Games

Back in mid-May of last year, Anita Sarkeesian launched a Kickstarter project to help fund her video series on portrayals of women in video games called “Tropes vs. Women in Video Games”. Her initial goal was set at $6000 for a planned goal of making 5 videos (or so I can gather from the Kickstarter page), meaning that she wanted approximately $1200 per video. Her project ended up being funded at close to $160,000 and her intent grew to creating 12 videos. This means that, currently, she has successfully netted a little over $13,000 per video she intends to eventually release; an impressive feat. Her first video was released a few days ago (a few months late, relative to her stated delivery, but here nonetheless) and, hot-button topic that her project was, I felt inclined to watch it and see what $13,000 a video buys in terms of research quality, methodology, and explanatory power. From my impression of Anita’s first video, were I to work under the assumption that she was making a reasonable amount of money for her time, effort, and conclusions in this project, I think I could be so bold as to suggest that I’m wildly underpaid for what I do in terms of research and writing.

I may not be as well-paid, but I make up for it in smug self-satisfaction.

Since Anita suggests that it’s important to think critically about the more problematic aspects of things (in this case, the “damsel in distress” story found in some video games), I’m sure she would agree it would be important to think critically about what she presents in her first video, so let’s do just that. The gist of the video appeared to be that, as noted, women are sometimes portrayed as being placed into peril (typically by a male character) from which a male character saves them. How common are such portrayals in video games? That’s an excellent question; perhaps Anita could have mentioned some data that bear on the point. Are these portrayals more or less common in video games, relative to other forms of media, and have they been getting more or less common over time? Those are some other excellent questions, but you won’t find any discussion of them either. Of course, this was only part 1 of the video, so maybe Anita’s saving all of her research findings for part 2. After all, it would surely seem peculiar if, after asking for several thousand dollars to make these videos that she claimed would take her a substantial amount of time and research, she ended up releasing videos stating her preexisting opinions about the matter, putting very little actual research in. Peculiar indeed.

The first set of points that I would be critical about when evaluating this video, then, is that, in the roughly 25 minutes of it, she presents almost nothing that would typically fall under the umbrella of what many people would consider research: there’s no methodology mentioned, no data presented, and there’s no discussion of how she reached the conclusions that she does. What she does present are some anecdotes and a few assertions. Here’s a good for-instance: Anita notes that the theme of “man-saving-woman” is at least several thousand years old. Despite noting this, she then goes on to suggest that, in 1933, there were two things (Popeye and King Kong, apparently) that led to this theme becoming a foundational element in video games 50 years later. Is this theme a foundational element in gaming? Maybe, but from what Anita presents in her video there’s no way to know (a) what she means by “foundational element”, (b) whether she was correct in that assessment, or (c) whether her posited causal link even exists. That is, if Popeye and King Kong never existed, would video games have come to represent this damsel in distress story line as frequently or infrequently as they do? Given that this theme is at least as old as recorded history accordingly to Anita, one could reasonably suggest that Popeye and King Kong did very little stage-setting at all.

What is notably absent from Anita’s video – on top of any mention of methodology or data – is any attempt at an explanation as for why this theme appears to be relatively ubiquitous. Lacking anything resembling a formal explanation concerning this theme’s popularity, much less any attempts at ruling out alternative explanations, Anita sticks largely to just noting that the theme exists in some unspecified proportion of games and that she doesn’t seem to like it very much. So, to recap, that’s no mention of a method, findings, or an explanation of the topic being investigated. Of course, I’m not here to just be critical of the fact that this video likely cost her backers approximately $260 per minute to make, by my estimation, and ended up with nothing of value to show for it; I also want to see if whether, in a few minutes, I can do better than Anita in discussing important questions, analyzing data, and explaining the issues.

“On your mark, get set…Hey, how come only men are racing in this picture?!”

So why might it be that it’s typically men who are portrayed as the saver of the woman, rather than the reverse? Why might it be that men are portrayed as predominately trying to save women, rather than other men? In order to answer those questions, it is helpful to first consider a third question: why is it the case that when a species of animal has one sex that displays a costly ornament – like peacocks – or one sex that engages in costly competition – like bowerbirds or rams – that this sex is most frequently the males? Here’s one candidate explanation that doesn’t work: peacocks have evolved such decorative plumes that they display for peahens in order to reduce the peahens to mere objects. The display itself serves the function of reducing peahens to powerless objects so that male peacocks can thus be empowered protagonists in their own male power fantasies. Though this explanation might sound silly on the grounds that you think that peacocks and peahens don’t think that way, there’s a better reason for discounting such an explanation: objectifying one sex to empowering the other doesn’t do anything biologically useful. As the explanation stands, it’s incomplete at best. Rather than explaining the phenomenon in question, the explanation phase is just pushed back one step to: why would peacocks benefit by objectify peahens? Where’s the reproductive payoff for a psychology that did that?

Here’s an altogether more plausible alternative explanation: peacocks have evolved this trait and display it because peahens were more inclined to mate with males that had larger, costlier, and harder-to-fake signals of phenotypic quality (Zahavi, 1975). Peahens favored such males because these costly signals served as viable reproductive guarantees of healthy offspring, and male behavior and physiology changed to suit the preferences of females so as to capitalize on the increased potential for reproduction. Peacocks behave this certain way, then, to attract mates; not to objectify or disempower them. To couch this in terms of a specific video game example Anita mentions, Mario doesn’t rush into Bowser’s castle in order to reduce Princess Peach to a helpless object; he does so because, by doing so, he’s increasing the chances he’ll have the opportunity to have or maintain a relationship with her (though whether or not this is his conscious motivating drive is a separate question).

With this explanation in mind, let’s do our best to imagine that peacocks and peahens decided to do distinctly human-like things, such as fantasizing and telling stories. What would the content of such things tend to be,? It seems that the sex of the individual in question would matter a great deal: the males might be enthralled by imagining tales of conflicts between other males with impressive ornaments, both displaying them for a desired female, and fantasize about displaying such an impressive ornament that the female who observed it couldn’t help but fall madly in love with him. Females, on the other hand, might find stories about other females deciding between their various competitors to be altogether more engaging, fantasizing about the social intricacies of deciding upon one male or another. You could think the distinction being something along the lines of the peacocks enjoying movies more along the lines of Die Hard and peahens being more inclined towards Twilight. Both stories involve a good deal of male-male competition, but the focus of the story would either center on the male or female perspective in that competition.

Let’s finally assume that this species of bird came across the technological capabilities to translate their fantasies into video games. Arguably, it’s easier to translate certain aspects of the the typical male fantasy into something resembling a video game that’s entertaining to play. While one could easily imagine a game where a peacock moves from level to level by out-competing his rivals, it’s less easy to imagine a game centered around female choice of partners (more succinctly, while Twilight might make an appealing series of books and movies, it might not make a good video game). Tying this back to Anita’s video, she seems to suggest that male video game designers are trying to tap into male power fantasies to sell more video games and, importantly, that they do this to the exclusion of women. What she did not seem to consider are two alternative explanations: (1) how easily are typically male and female fantasies turned into entertaining video games and/or (2) are the people making these games simply expressing their own preferences for what they find appealing, rather than trying to explicitly appeal to the preferences of others? Regarding that second point, imagine asking men to write a story that they were either trying to sell or not sell: would the content of these stories between the two groups differ significantly in terms of major themes, like the use of a damsel in distress? Certainly an interesting question: perhaps it’s one that Anita might have considered answering…

Or, you know, she could just take pictures in front of video games; that works too.

So we now have the beginnings of a plausible explanation for understanding the first question (why are men typically rescuing women, rather than the reverse) and have considered some alternative explanations as to why such a theme might be as common as it is across time and genres. It might not be too much, but it’s at least a start, providing us with some considerations that help us interpret the meager amount of information Anita offers.

To conclude, let’s briefly consider further why some of Anita’s beliefs about the motivations of male video game characters and designers, are, at the very least, likely in need if revision. There is another research finding that casts severe doubt on the “men view women as helpless objects in need of saving” angle that Anita seems to favor. When a mixed-sex group of 3 people was made up of 2 men and 1 woman, men were found to universally volunteer and end up in a role that caused them discomfort; what awful paternalistic sexist crap, right? Surely women could handle that discomfort just as well as the men, so men must be pushing women out of the hero role to fulfill their own power fantasies. By contrast, however, when then groups were made up of 1 man and 2 women, men ended up in this “protective” role at chance levels (McAndrew & Perilloux, 2012). So unless the hypothesis is to be amended to “men tend to view women as powerless and in need of rescue but only in the presence of other men (or, perhaps, when women are relatively scarce); oh, and also women tend feel the same way about the whole being protected by men thing”, one could conclude there’s likely some wrong with Anita’s hypothesis. If only she had done some kind of research to figure that out…

(I’d also like to note, as a bit of off-topic point, the apparent contrast between Anita’s proposed videos #4 and #9. It looks like she’s exploring the trope of women being sexy and evil in 4, and the trope of being unattractive and evil in 9, both of which are apparently unacceptable. Damned if the villainess is attractive; damned if she isn’t. But hey, only an approximate $260 per minute for this knowledge, right?)

References: McAndrew, F.T. & Perilloux, C. (2012). Is self-sacrifical competitive altruism primarily a male activity? Evolutionary Psychology, 10, 50-65

Zahavi, A. (1975). Mate selection—A selection for a handicap Journal of Theoretical Biology, 53 (1), 205-214 DOI: 10.1016/0022-5193(75)90111-3





Does Infidelity Pay Off (For Sparrows)?

For some species, mating can be a touch more complicated than others. In species where males provide little more than their gametes, the goal of mating for females is simple: get the best gametes available. While the specifics as to how that’s accomplished vary substantially between species, the overall goal remains the same. Since genes are all the female is getting, she may as well get the best that she can. In contrast, for some other species males provide more than just their genes; they also provide some degree of investment, which can take the form of a one-time gift through upwards of decades of sustained investment. In these species, females need to work this additional variable into their mating calculus, as the two goals do not always overlap. The male who’s willing to provide the best investment might not also happen to have the best genes, and pursuing one might risk the other.

Accordingly, it’s long been assumed that extra-pair mating (cheating) is part of the female strategy to have her cake and eat it too. A female can initiate a pair-bond with a male willing to invest while simultaneously having affairs with genetically higher-quality males, leaving the unfortunate cuckold to invest in offspring he did not sire. Undertaking extra-pair matings, however, can be risky business, in that detection by the investing male might lead to a withdrawal of investment and, in certain cases, bodily harm.

Good luck to all you parents when it comes to weaving that tidbit into your birds and bees talk.

These risks would require that offspring sired through extra-pair mating to tend to actually be fitter than offspring sired by the within-pair male, in order to be selected for. Abandonment can entail some serious risks, so females would need some serious compensating gains to offset that fact. A new paper by Sardell et al (2012) sought to determine whether extra-pair offspring would in fact be ‘fitter’ than within-pair offspring in Melospiza melodia – the song sparrow – when fitness was measured by lifetime reproductive success in number of offspring hatched, the number that survived to enter the breeding population, and the number of grand-offspring eventually produced. The results? Data gathered across 17 years, representing 2,343 hatchlings and 854 broods found that extra-pair offspring seemed to actually be less fit than their within-pair half-siblings. Well, kind of… but not really.

Over the 17 years of data collection, roughly 28% of the offspring were classed as being extra-pair offspring, and only broods with mixed paternity was considered for the present study (i.e. there was at least 1 offspring from the resident male and also at least 1 offspring from an extra-pair male). This cut the sample size down to 471 hatchlings, representing 154 mixed paternity broods across 117 pair bonds. The first point I’d like to make is that a 28% non-paternity rate seems large, and, unless it’s the result of an epidemic of forced copulations (rape), that means these female sparrows are having a lot of affairs, presumably because some mating module in their brain is suggesting they do

Within the sample of sparrows, female extra-pair offspring (the ones who were sired by the non-resident male) averaged 5.4 fewer hatched offspring over their lives, relative to their within-pair half-siblings; for extra-pair males, the corresponding average was 1.5 fewer offspring. However, not all of those hatchlings live to eventually breed. Of the 99 that did, the females that were the result of  extra-pair mating, on average, had 6.4 fewer hatchlings of their own, relative to the within-pair females; the extra-pair males also had fewer hatchlings of their own, averaging 2.6 fewer. Thus, relative to their within-pair half-siblings, extra-pair offspring seemed to produce fewer offspring of their own, and, in turn, fewer grand-offspring. (I should note at this point that any potential reasons for why extra-pair young seemed to be having fewer hatchlings are left entirely unexamined. This strikes me as something of a rather important oversight)

Are we to conclude from this pattern of results (as this article from the Huffington post, as well as the authors of the current paper did) that extra-pair mating is not currently adaptive?

And is it time for those who support the “good genes” theory to start panicking?

I don’t think so, and here’s why: when it came to the number of recruited offspring – the hatchlings who eventually reached breeding age – extra-pair females ended up having 0.2 more of them, on average, while extra-pair males had 0.2 less of them, relative to their within-pair half-siblings. While that might seem like something of a wash, consider the previous finding: within-pair offspring were having more offspring overall. If within-pair offspring tended to have more hatchlings, but a roughly equal number reach the breeding pool, that means, proportionally, more of the within-pair offspring were dying before they reached maturity. (In fact, extra-pair offspring had a 5% advantage in the number of total hatchlings that ended up reaching maturity) Having more offspring doesn’t mean a whole lot if those offspring don’t survive and then go on to reproduce themselves, and many of the within-pair offspring were not surviving.

One big area this paper doesn’t deal with is why that mortality gap exists; merely that it does. This mortality gap might even be more surprising, given that the potential risk of abandonment might mean males were less likely to have been investing when they doubted their paternity, though the current paper doesn’t speak to that possibility one way or another. Two of the obvious potential suspects for this gap are predation and parasites. Extra-pair young may be better able to either avoid predators and/or defend against pathogens because of their genetic advantages, leading to them being more likely to survive to breeding age. Then there’s also a possibility of increased parental investment: if extra-pair hatchlings are in better condition, (perhaps due to said pathogen resistance or freedom from deleterious mutations) the parents may preferentially divert scarce resources to them, as they’re a safer wager against an uncertain future. Alternatively, extra-pair offspring might have commanded a higher mating value, and were able to secure a partner more able and/or willing to invest long term. There are many unexplored possibilities.

The heart of the matter here concerns whether the female sparrows who committed infidelity would have been better off had they not done so. From the current data, there is no way of determining that as there’s no random assignment to groups and no comparison to non-mixed paternity broods (though that latter issue comes with many confounds). So not only can the data not definitely determine whether the extra-pair mating was adaptive or not, but the data even suggests that extra-pair offspring are slightly more successful in reaching breeding age. That is precisely counter to the conclusions reached by Sardell et al (2012), who state:

Taken together, these results do not support the hypothesis that EPR [extra-pair reproduction] is under positive indirect selection in female song sparrows…and in fact suggest… [that] other components of selection now need to be invoked to explain the evolution and persistence of EPR.

Their data don’t seem to suggest anything of the sort. They haven’t even established current adaptive value, let alone anything about past selection pressures. Sardell et al ‘s (2012) interpretation  of this mountain of data seems to be biting off more than they can chew.

It was a good try at least…

One final thoroughly confusing point is that Sardell et al (2012) suggest that how many grand-hatchlings the extra-pair and within-pair young had mattered. The authors concede that, sure, in the first generation within-pair sparrows had more hatchlings, proportionately more of which died, actually leaving the extra-pair offspring as the more successful ones when it came to reaching the breeding pool. They then go on to say that:

However, since EPY [extra-pair young] had 30% fewer hatched grandoffspring than WPY [within-pair young], higher recruitment of offspring of EPY does not necessarily mean that EPY had higher LRS [lifetime reproductive success] measured to the next generation. (p.790)

The obvious problem here is that they’re measuring grandoffspring before the point when many of them would seem to die off, as they did in the previous generation. So, while number of hatched grandoffspring says nothing important, they seem to think it does this time around. It’s been known that counting babies is only of limited use in determining adaptive value (let alone past adaptive value), and I hope this paper will serve as a cautionary tale for why that’s the case.

References: Sardell, R., Arcese, P., Keller, L., & Reid, J. (2012). Are There Indirect Fitness Benefits of Female Extra-Pair Reproduction? Lifetime Reproductive Success of Within-Pair and Extra-Pair Offspring The American Naturalist, 179 (6), 779-793 DOI: 10.1086/665665