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Dec 21 2012

Readings in Evolutionary Psychology

I know you’re all still very interested in the subject of evolutionary psychology. Given that, I’ve collected a short selection of readings that may interest you. First, we start with the incomparable Scicurious and her Friday Weird Science feature.

The handsome stranger clutched her shoulders, supporting her as she swooned. The suddenness and violence of the robbery and her rescue disoriented Beverlee, and for a few moments she did not know where she was. But as she began to be conscious of her surroundings, she was increasingly aware of the tall, firm man she leaned against, of his  big hands clasped around her shoulders, warm through the thin linen of her chemise.

She looked up hesitantly through her lashes, and into the dark, deep eyes of her rescuer. As their eyes met, a shock seemed to pass through them both. He leapt backward, and for an instant Beverlee felt the loss of his touch, the coldness where his hands had touched her.  But the moment passed, and gathering himself, her rescuer spoke.

“Christmas” he said, flatly. “Bride baby cowboy doctor secret lady.” And each word sang deep in Beverlee’s spirit, tapping something deep in her she hadn’t known existed: the desire to find a long term mate that would provide food and shelter while she had loads of babies.

-from the romance novel I will someday write.

Sci takes a look at the methods behind a study purporting to show that inherent tendencies in female mating strategies are reflected in Harlequin romance titles. Hey, now, come on. They looked at 15,000 titles. How can a sample size that large not represent good science? I doubt I’ll spoil much to let to you know that Sci will tell you. She’ll also be hilarious as she does it. 

Once you’re done with Sci’s post, turn your attention to NPR and Barbara King’s science blog.

Of the 100 “top science stories for 2012″ chosen by Discover Magazine, I am most fascinated by #42: “The Myth of Choosy Women, Promiscuous Men.” It reports a serious challenge to an experiment that has remained a touchstone in evolutionary biology for over 50 years.

The study, on fruitfly mating, was done in 1948 by geneticist A.J. Bateman. Bateman showed that the male insects’ strategy was to mate with many females, whereas the females’ strategy was to be discriminating in their choice of partners. Male reproductive success, in other words, correlated positively with number of mates, but female reproductive success did not.

Now, ecologist and evolutionary biologist Patricia Gowaty and her colleagues Yong-Kyu Kim and Wyatt Anderson have repeated that study. They conclude something startling: Bateman blew it.

Bateman’s study has been fundamental to much theorizing on sex-specific mating strategies. His 1948 paper has been cited more than 2,000 times. The idea that females are choosy and males are promiscuous due to inequalities in parental investment is referred to as Bateman’s principle, despite much subsequent evidence that mating strategies are much more varied than such a principle would account for. It will be interesting to see what impact this new study will have on citation of the original study and of derived work.

Now, if you think I’m only going to point you to sources critical of evo psych, you’re wrong. Evolutionary Psychology, an open source journal in the field, has a special issue out on applied evolutionary psychology. (See Issue 5 at the bottom of the 2012 archive.)

How can evo psych help us solve the problems of the world? There are a number of ways suggested by the papers in this issue. One of them in particular caught my eye “Attractive skin coloration: Harnessing sexual selection to improve diet and health“. And how does sexual selection improve health? It can get us to eat more fruit and vegetables. Sort of. From the extract:

We argue that the benefits to appearance may motivate individuals to improve their diet and that this line of appearance research reveals a potentially powerful strategy for motivating a healthy lifestyle.

That, of course, is just the abstract, but this is an open-source journal. The relevant portion of the article?

The impact of fruit and vegetable consumption on skin color could be utilized in a similar way to promote healthy eating. The empirical studies outlined above allow quantification of the impact that carotenoid pigmentation has on skin color. Coupled with this, existing image manipulation techniques (e.g., Burt and Perrett, 1995; Stephen et al., 2009) can be used to transform images of participants’ own faces along a skin color axis to accurately illustrate varying degrees of fruit and vegetable consumption (Figure 1). We propose that individuals could view manipulated images of their facial photograph alongside existing effective dietary intervention techniques such as setting dietary goals and self-monitoring progress (see Pomerleau, Lock, Knai, and Mckee, 2005).

It is important to highlight the results of psychophysical studies to intervention participants. Individuals may be more strongly motivated to increase their fruit and vegetable consumption if it is made clear that even modest dietary change is sufficient to confer perceptible skin color benefits (e.g., Whitehead et al., 2012c). It is also important that participants recognize the rapidity of the impact on skin color (Whitehead et al., 2012c) as existing dietary interventions typically concentrate on long-term benefits to health and overlook shorter-term incentives.

The researchers took data on the skin color change caused by increasing the fruit and vegetables in one’s diet (giving one a slightly more warm color), assumed that this effect scaled, created pictures based on this, discovered that people thought warmer skin tones indicated better health. They then connected this to attractiveness and concluded the above.

Now, it’s worth noting that the average picture was decided to be optimally healthy with an increase of six servings daily. Given that current recommendations in a 2,000-daily-calorie diet is nine daily servings, this suggests that college students engaging in dreadful dietary habits (assuming that serving portions are consistent internationally).

That points us toward the interesting part of these findings. Despite the presumably strong selection pressure for visible cues of health, this study makes it appear that we’re not particularly driven to eat a class of foods that creates this visible cue of health. That would seem to limit the applicability of this particular finding. It would suggest that whatever use would be derived from telling people that they would look more attractive if they ate more fruits and vegetables would come from the data-transmission involved. In other words, it would come from the social/cultural transaction and not from our brains inherently recognizing the adaptive nature of a diet change.

I haven’t read the rest of the studies yet, but I’m looking forward to them.

13 comments

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  1. 1
    Ichthyic

    I’m really disliking this cherry picking of science to attack entire fields. I work in animal behavior, and have seen even worse papers and conclusions appear in MUCH bigger journals over the years.

    seriously, this smacks of the attacks on sociobiology in the late 70s/early 80s.

    It’s ugly, and it ain’t how we do this.

    we do this through the journals themselves.

  2. 2
    Ichthyic

    In fact, if you want to see how issues like this are actually discussed by people practicing in the relevant fields, you might try taking a gander at how Jerry Coyne presents his critiques of Evo Psych:

    http://whyevolutionistrue.wordpress.com/2012/12/10/is-evolutionary-psychology-worthless/

    FWIW, at the base of it, the idea that one should examine selection and human behavior is NOT an unreasonable one.

    projects that do that, while ignoring all other hypotheses, are rightly criticized, but not all do that, not even in evo psych, just like they don’t in sociobiology, or in behavioral ecology.

  3. 3
    Stephanie Zvan

    No. The people working in the field do it through the journals themselves. If they do not–and in this field, they largely do not–then the rest of us have to pick up the slack.

    Science isn’t some isolated little thing that sits nicely in the journals and never bothers anyone else. It is our best shot at understanding the world, and as such, it has enormous influence. When the people who have stepped up and said, “Hey, I got this!”, continually do a crappy job that is clearly visible even to non-specialists, are we just supposed to take what they churn out? Would you accept that behavior from another field? No.

    Nor is this something we do only to evolutionary psychology. Nor is it cherry picking. I linked to coverage of a good study last week. Today I grabbed the first paper from Evolutionary Psychology where the title jumped out at me and included it here after seeing several Twitter links from science writers about this special issue. I didn’t even pick one of the papers that was being criticized there. It should have had a very good chance of being something worthwhile, right? Turns out it wasn’t, but there was no cherry picking involved.

    And if the people who work in related fields are as specific in their criticisms and vague and pale in their praise as Coyne has been, you can continue to color me unimpressed.

  4. 4
    Stein

    Stephanie, your’e not proving anything else than your political obstination through evident cherry picking and tiresome insistance. Even though you are skilled enough in rhetorics to take down most commenters, do you think you and a bunch of science fond and politically compromised bloggers have the authority to discredit a science field established for decades through light comments?

  5. 5
    Ichthyic

    If they do not–and in this field, they largely do not–then the rest of us have to pick up the slack.

    “in this field”

    please compare and contrast EXACTLY what is done, within the scientific community, through the journal system, for this field vs. say, behavioral ecology.

    When you can do that, I’ll think you have something useful to offer to an actual scientific discussion.

  6. 6
    Ichthyic

    where the title jumped out at me

    LOL

    right.

  7. 7
    Ichthyic

    have you looked at all journals that publish work relating to evo psych?

    have you compared that body of work to other, similar fields?

    no, you haven’t.

    really, don’t even TRY to claim you have.

    PZ hasn’t either, which is another thing that has become terribly disappointing in this whole thing.

    criticize papers, damnit, not fields of endeavor.

    Gould wrongly did that himself, and was rightly chastised for it. Learn from history, or real scientists will simply ignore you.

  8. 8
    Jensen

    You article is very try hard, and seems to have been motivated for the most part by politics.

    In particular, your criticism of the Whitehead, Ozakinci and Perrett paper is off-base, specifically this part:

    That points us toward the interesting part of these findings. Despite the presumably strong selection pressure for visible cues of health, this study makes it appear that we’re not particularly driven to eat a class of foods that creates this visible cue of health. That would seem to limit the applicability of this particular finding. It would suggest that whatever use would be derived from telling people that they would look more attractive if they ate more fruits and vegetables would come from the data-transmission involved. In other words, it would come from the social/cultural transaction and not from our brains inherently recognizing the adaptive nature of a diet change.

    Where you seem to be making the argument:

    (1) EP claims SOME behaviors are heritable

    (2) here is ONE behavior that does not seem to not be heritable

    (3) therefore, EP is false.

    Which is an error in logic.

    The Whitehead, Ozakinci and Perrett is not a stellar example of EP; but this is only because its conclusion, ‘eating healthy foods makes you look more attractive, sharing this information may further incentiveize a healthy lifestyle’, is not very important, not that it is any way wrong.

  9. 9
    jose

    It’s almost like Coyne had never chastised evolutionary psychology as a whole for their alarmingly lax standards, literally telling evolutionary psychologists that if they policed their discipline better, he wouldn’t have to. There’s only so many papers you can shrug off as cherry-picking before their numbers start to tip the scales.

    Of course everybody agrees on the essential core concept. It’s this specific, current incarnation that would benefit from an overhaul. From Pigliucci:
    Like in the case of psychoanalysis, the problem is not that the basic ideas aren’t sound: sex surely is a fundamental drive of human urges and emotions, and therefore must play an explanatory role in a variety of human behaviors, just like psychoanalysts would have it. Likewise, evolutionary psychologists are certainly correct that natural selection must have played a role in shaping human behaviors and cognitive abilities, as general evolutionary theory would predict. The trouble starts when we get to detailed scenarios aiming at accounting for individual instances.”

    Let’s not pretend the only source of criticism to evolutionary psychology is Rebecca Watson & friends, mkay?

    Now, as a sign of good faith, let me link you an example of a good study related to human behavior well within the frame of evolutionary theory, something I wish the majority of evopsych papers looked like. PDF.

  10. 10
    jose

    It’s very fortunate to have behavioral ecology mentioned in the thread! I happen to have a behavioral ecologist right here. Ouch.

  11. 11
    Stephanie Zvan

    Where you seem to be making the argument:

    (1) EP claims SOME behaviors are heritable

    (2) here is ONE behavior that does not seem to not be heritable

    (3) therefore, EP is false.

    Actually, it’s your reading comprehension that has problems or perhaps your understanding of science. This might help clear things up for you.

  12. 12
    Stephanie Zvan

    LOL

    right.

    Found out about the issue in the morning, when Neuroskeptic tweeted about it. Didn’t want either of the articles he tweeted dismissively about. Had half an hour at lunch to link Sci and Barbara’s posts, find and read one article from the journal, note what jumped out at me from the study, and make sure I was reading it right. Wrote the paragraphs following the excerpt on my smart phone the bus on the way home. Took me about 15 minutes.

    Is it supposed to be that easy to pick holes in a random journal article? Hell, no. However, it was. Feel free to find what you think is a stronger study in that issue that I should look at.

    Also, fuck you. I was every bit as prepared to put up an interesting evo psych finding as…well, in this case, a possible application for social psychology. I’m sick of you whiny fanboys who see every criticism as trying to tear down the edifice of science, and it hurts me not at all when I point out bad design and reasoning to have pointed out the good.

    have you looked at all journals that publish work relating to evo psych?

    have you compared that body of work to other, similar fields?

    no, you haven’t.

    really, don’t even TRY to claim you have.

    In 1989, a beloved professor introduced me to the concept of what was then still largely referred to as sociobiology. It sounded very interesting, though I ended up focusing elsewhere in psychology. It has been disappointing me for the last 23 years.

    I enjoy reading papers. I enjoy methodology and the geekery of methodological concerns. There is not nearly the degree of critical discussion of evolutionary psychology methods in their literature that there is in social psychology or in measurement. There is not the same degree of grappling with criticisms from outside the field or even acknowledging them.

    Deal.

  13. 13
    Martha

    Thank for the links, Stephanie.

    As for the comments, I do hope you’ll alert us if they EP fanboys ever make sense. I can’t continue to read them in the vain hope that they will. Thanks!

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