Do Humans Have Innate Concepts for Thinking About Other People?

Gossip is one of life’s greatest consolations and one of our most reliable conversational fall-backs. In a world without gossip, many of us could realize Tim Ferriss’s ideal of a Four-Hour Work Week without even putting any of his advice into practice. Gossip is also, according to the anthropologist Donald Brown (1991), a human universal—one of those pan-human traits that people within every world society can be expected to evince.

Our ability to gossip, as is the case with all ostensive communication, is premised on the idea that our listeners are in possession of concepts that enable them to convert the sounds coming out of our mouths into ideas that resemble those we are trying to convey. Which got me to thinking about the psychology that makes gossip possible: Are there universal “person concepts”—species-typical cognitive representations of particular human traits or attributes—that every human reliably acquires during normal development? If you flew back from your vacation in Tanzania with a Hadza man or woman whom you planned to entertain in your home for a couple of weeks, would the two of you be able to settle into your living room and enjoy a little TMZ* (assuming you spoke Hadza and could translate)? The Hadza are arguably the last full-time hunter-gatherer society on the planet; it’s difficult to imagine a society more different from our own. Could you trust that your Hadza friend had acquired all of the person concepts that would enable him or her to follow the action? Are there any universal and native social concepts upon which all humans rely in order to make social life work?

I’ll get to that in a moment, but first a slightly bigger question: Does the mind contain any native concepts at all? Here in 21st century, many scholars in the social sciences would answer this question affirmatively, having turned their backs on the most hardcore versions of the Blank Slate theory that Steven Pinker describes in his aptly titled (2002) book, The Blank Slate. (The Major Blank-Slater of Western thought, John Locke, famously wrote “If we will attentively consider new-born children, we shall have little reason to think that they bring many ideas into the world with them.”). Even so, there is still much to be debated and discovered about innate ideas.

For starters, how many innate ideas are there? Conceding that there are more than zero of them is not a particularly bold claim. Are there handfuls? Dozens? Scores? Many evolutionary psychologists and cognitive scientists prefer large numbers here, and not without good reason: It’s difficult to imagine how even the basic behavioral tasks that humans must accomplish to stay alive—finding food, water, and warmth, for starters—could be accomplished unless the mind contained some built-in conceptual content.

To Find Food, a Newborn Baby Needs FOOD

Since Locke brought up the case of “new-born children,” let’s think about babies for a moment. A newborn infant comes into the world with a pressing problem: She must find something to eat. Locke thought the infant came into the world with the ability to experience hunger, but he did not think the infant came into the world with a concept of FOOD. The so-called Frame Problem, which Daniel Dennett (2006) so vividly described, makes it unlikely that a newborn infant could solve this problem (“Find food”) before it starved unless it had some built-in representation of what FOOD is. The selection pressure for the evolution of a conceptual short-cut here is enormous: Successful food-finding in the first hour after birth is a predictor of infant survival, so that first hour matters. The clock is ticking. Therefore, a cognitive design that requires infants to find food on a blind trial-and-error basis is likely to be a losing design in comparison to a design that comes with a built-in concept for FOOD from the outset.

For human infants, the FOOD concept involves the activity of neurons that respond to the olfactory properties of specific volatile chemicals that human mothers emit via the breast, possibly along with visual and tactile features of the human breast as well (Schaal et al., 2009). Through a matching-to-template process, human infants can quickly locate breast-like objects in their environments, which of course are the only objects in the universe that are specially designed to provide human neonates with nutrition and hydration.

What about More “Complex” Concepts?

Convincing you that human neonates possess an innate concept for FOOD is perhaps an easy sell, but in a recent paper in Current Directions in Psychological Science, Andy Delton and Aaron Sell (2014) argued that humans come to possess a variety of universal and reliably developing social concepts as well, which enable them to regulate the universal components of human social life. For Delton and Sell, there can be “no motivation without representation,” so if there are certain adaptive challenges that humans have evolved behavioral programs to surmount, there should also be concepts within the human mind that enable them to parse their worlds into adaptively meaningful units so that the stimuli that are relevant to achieving those adaptive goals can be easily identified.

Delton and Sell’s list of candidates for intuitive concepts (which they in no way claim to be exhaustive) includes COOPERATOR, FREE RIDER, NEWCOMER, KINSHIP, ROMANTIC PARTNER, ROMANTIC RIVAL, ENTITLEMENT, DISRESPECT, INGROUP, and OUTGROUP, among others (see the Table below). The claim here, again, is that if humans are going to have evolved goals that involve “establishing cooperative relationships,” “deterring free riders,” or “evaluating whether to engage in trade with someone from an outgroup,” they will need concepts to represent what COOPERATORS, FREE RIDERS, and OUTGROUPS actually are. There can be no motivation without representation.

(By the way, to claim that such concepts are “innate” or “native” is not to claim that they are present in the mind from birth, but rather, that the human genome possesses the programs for assembling these representations within the mind at developmentally appropriate points in the human life cycle, and with appropriate kinds of environmental inputs. Concepts come and concepts go as we develop. Think of how the concept of FOOD gets overwritten once infants turn away from breast milk and toward other foods during the first three to four years of life. The FOOD concept within the mind/brain changes over ontogeny, but the genes that give rise to that initial FOOD concept—which the infants match against environmental inputs on the basis of the olfactory, visual, and tactile information—remain in the genome and are passed onto one’s genetic heirs so the concept can be re-constructed during ontogeny.)

Delton-Sell-Figure1From Delton and Sell, 2014

Looking for Universal Concepts in the Dictionary

Another paper was recently published that provides some confirmatory evidence, of a sort, for Delton and Sell’s position. The personality psychologist Gerard Saucier and his colleagues (2014) read through the English dictionaries representing the languages of 12 geographically and linguistically distinct cultural groups from all over the world (see Table below) in hopes of finding the universal concepts that humans use to parse up the actions and dispositions of other humans.

Saucier_Figure1From Saucier et al., 2014

The logic behind Saucier et al.’s effort was straightforward: All human societies should end up making words to represent the attributes that humans universally use to parse their social lives—presuming, I suppose, that those concepts are worth talking about. (Universal social concepts for which humans universally make words might be only a subset of all universal social concepts: Some universal social concepts might not be worth talking about, though I can’t think off-hand of what such concepts might be. Can you?)

By scouring these dictionaries, Saucier and colleagues ultimately located nearly 17,000 words across the 12 languages that could be used to refer to human attributes. Through a reduction process that enabled them to thrown out synonyms and variations on common roots (fool, foolish, foolishly, “to fool,” and “to be fooled” can all be reduced to a single attribute concept, as can all of the other words that gloss in English as “to be foolish”), they were able to greatly simplify the number of attribute concepts within each language to more manageable numbers.

Having reduced each language’s human attribute lexicon down in this fashion, they then looked for attribute terms that cropped up in either (a) all 12 of the languages they studied; or (b) 11 of the 12 languages they studied. With their “11 out of 12” rule, they were taking a cue from the anthropologist Donald Brown, who argued that “Human Universals” should be manifest in the ethnographic materials for 95% of the world’s societies. Placing the empirical estimate at 100% would be too strict because it doesn’t allow for ethnographers’ oversights. With only 12 dictionaries to work with, 11 out of 12 is as close as you can come to 95%.

What Saucier and colleagues discovered was fascinating. All twelve languages had human attribute concepts corresponding to BAD, GOOD, USELESS, BEAUTIFUL, DISOBEDIENT, STUPID, ALIVE, BLIND, SICK, STRONG, TIRED, WEAK, WELL, AFRAID, ANGRY, ASHAMED, JEALOUS, SURPRISED, BIG, LARGE, SMALL, HEAVY, OLD, and YOUNG. If you use the slightly more lenient “11 out of 12” criterion for judgments of universality, you get to add EVIL, HANDSOME, GOSSIP, HUMBLE, LOVE, CLUMSY, DRUNK, FOOLISH, QUICK, SLOW, UNABLE, WISE, DEAD, SLEEPY, HUNGRY, PAIN, PLEASURE, THIRSTY, HAPPY, SATISFIED, TROUBLED, FAT, LITTLE, SHORT, TALL, MARRIED, POOR, RICH, and STRANGER.

To me, this is a fascinating list. Some of the traits on the list involve moral evaluation (e.g., BAD, GOOD, EVIL, HUMBLE). Others clearly have to do with physical health, condition, or capacity for work (e.g., ALIVE, BLIND, SICK, WELL, QUICK, SLOW, UNABLE, STRONG, WEAK). Others relate to reproductive value (e.g., BEAUTIFUL, HANDSOME, MARRIED), and age (YOUNG, OLD). Many of the universals relate to more temporary motivations, emotions, and behavioral dispositions (e.g., TIRED, AFRAID, ANGRY, ASHAMED, JEALOUS, SURPRISED, PLEASURE, THIRSTY, HUNGRY, PAIN, COLD, HOT). And still others are associated with reliability and judgment (e.g., CLUMSY, WISE, RIGHT, USELESS). I think Delton and Sell would be especially pleased to see that STRANGER even makes it to the list—consistent with their speculation that humans possess innate “NEWCOMER TO A COALITION” and “OUTGROUP” concepts.

I wouldn’t want to overstate the significance of Saucier and colleagues’ findings (although I think the findings are extremely important): As I mentioned above, just because we lack a word for something doesn’t mean we don’t have an innate concept for it (remember that infants can find food because they come into the world with a well-developed FOOD concept, even though they can’t converse with you about food). Saucier’s list of universal person words almost surely does not exhaust the list of evolved person concepts that humans reliably acquire through ontogeny, but it might be a decent rough draft of the set of person concepts that all adults eventually find regular occasions to gossip about. And of course, if you can count on the fact that your Hadza houseguest has concepts for Bad, Good, Beautiful/Handsome, Love, Drunk, Sick, Ashamed, Jealous, Fat, Short, Old, Young, Rich, and Poor, then translating an episode of TMZ for him or her should be no trouble whatsoever.

Postscript: After reading this post, Paul Bloom wrote me to ask why I “didn’t mention the enormous  developmental psych literature that looks at exactly this question—work that studies babies with an eye toward exploring exactly which concepts are innate and which are learned, e.g., Carey, Baillergeon, Wynn, Spelke, Gergely, Leslie, and so on.” (Paul was too modest, I think, to put himself to this list, but he should have.) Hat in hand, I couldn’t agree more. If you don’t know the work of the scientists that Paul mentioned above, you can look to it for further evidence that humans come into the world with complex social concepts. ~MEM

References

Brown, D. E. (1991). Human universals. Boston, MA: McGraw-Hill.

Delton, A. W., & Sell, A. (2014). The co-evolution of concepts and motivation. Current Directions in Psychological Science, 23(2), 115-120.

Dennett, D. C. (2006). Cognitive wheels: The Frame Problem of AI. New York: Routledge.

Pinker, S. (2002). The blank slate: The modern denial of human nature. New York: Viking.

Saucier, G., Thalmayer, A. G., & Bel-Bahar, T. S. (2014). Human attribute concepts: Relative ubiquity across twelve mutually isolated languages. Journal of Personality and Social Psychology, 107(1), 199-216.

Schaal, B., Coureaud, G., Doucet, S., Delaunay-El Allam, M., Moncomble, A.-S., Montigny, D., . . . Holley, A. (2009). Mammary olfactory signalisation in females and odor processing in neonates: Ways evolved by rabbits and humans. Behav Brain Res, 200, 346-358.

*I trust that you were able to infer that by TMZ I meant the celebrity gossip show and not the cancer drug or the Soviet motorcycle manufacturer.

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The Myth of Moral Outrage

This year, I am a senior scholar with the Chicago-based Center for Humans and Nature. If you are unfamiliar with this Center (as I was until recently), here’s how they describe their mission:

The Center for Humans and Nature partners with some of the brightest minds to explore humans and nature relationships. We bring together philosophers, biologists, ecologists, lawyers, artists, political scientists, anthropologists, poets and economists, among others, to think creatively about how people can make better decisions — in relationship with each other and the rest of nature.

In the year to come, I will be doing some writing for the Center, starting with a piece I that has just appeared on their web site. In The Myth of Moral Outrage, I attack the winsome idea that humans’ moral progress over the past few centuries has ridden on the back of a natural human inclination to react with a special kind of anger–moral outrage–in response to moral violations against unrelated third parties:

It is commonly believed that moral progress is a surfer that rides on waves of a peculiar emotion: moral outrage. Moral outrage is thought to be a special type of anger, one that ignites when people recognize that a person or institution has violated a moral principle (for example, do not hurt others, do not fail to help people in need, do not lie) and must be prevented from continuing to do so . . . Borrowing anchorman Howard Beale’s tag line from the film Network, you can think of the notion that moral outrage is an engine for moral progress as the “I’m as mad as hell and I’m not going to take this anymore” theory of moral progress.

I think the “Mad as Hell” theory of moral action is probably quite flawed, despite the popularity that it has garnered among may social scientists who believe that humans possess “prosocial preferences” and a built-in (genetically group-selected? culturally group selected?) appetite for punishing norm-violators. I go on to describe the typical experimental result that has given so many people the impression that we humans do indeed possess prosocial preferences that motivate us to spend our own resources for the purpose of punishing norm violators who have harmed people whom we don’t know or otherwise care about. Specialists will recognize that the empirical evidence that I am taking to task comes from that workhorse of experimental economics, the third-party punishment game:

…[R]esearch subjects are given some “experimental dollars” (which have real cash value). Next, they are informed that they are about to observe the results of a “game” to be played by two other strangers—call them Stranger 1 and Stranger 2. For this game, Stranger 1 has also been given some money and has the opportunity to share none, some, or all of it with Stranger 2 (who doesn’t have any money of her own). In advance of learning about the outcome of the game, subjects are given the opportunity to commit some of their experimental dollars toward the punishment of Stranger 1, should she fail to share her windfall with Stranger 2.

Most people who are put in this strange laboratory situation agree in advance to commit some of their experimental dollars to the purpose of punishing Stranger 1’s stingy behavior. And it is on the basis of this finding that many social scientists believe that humans have a capacity for moral outrage: We’re willing to pay good money to “buy” punishment for scoundrels.

In the rest of the piece, I go on to point out the rather serious inferential limitations of the third-party punishment game as it is typically carried out in experimental economists’ labs. I also point to some contradictory (and, in my opinion, better) experimental evidence, both from my lab and from other researchers’ labs, that gainsay the widely accepted belief in the reality of moral outrage. I end the piece with a proposal for explaining what the appearance of moral outrage might be for (in a strategic sense), even if moral outrage is actually not a unique emotion (that is, a “natural kind” of the type that we assume anger, happiness, grief, etc. to be) at all.

I don’t want to steal too much thunder from the Center‘s own coverage of the piece, so I invite you to read the entire piece over on their site. Feel free to post a comment over there, or back over here, and I’ll be responding in both places over the next few days.

As I mentioned above, I’ll be doing some additional writing for the center in the coming six months or so, and I’ll be speaking at a Center event in New York City in a couple of months, which I will announce soon.

Happy International Forgiveness Day!

August is a notoriously slow month for news (and blogging). It’s also somewhat bereft of holidays and official days of observance. According to the web site Holiday Insights, August does host a few official holidays (that is, days of observance that were established by presidential proclamation or acts of Congress). These include U.S. Coast Guard Day, National Lighthouse Day, Aviation Day, Senior Citizen’s Day, and Women’s Equality Day. The unofficial August holidays, I have just learned, also include National Dog Day, Presidential Joke Day (on August 11, 1984, President Reagan joked into a live microphone that the U.S. had officially outlawed “Russia” and would begin bombing five minutes thereafter), and Vesuvius Day (take a guess). But these are the exceptions that prove the rule: August is a month in which we’re not encouraged to be mindful of very much.

Even so, over the past couple of years, I’ve become rather fond of today, the first Sunday in August: This is the day on which a group called the Worldwide Forgiveness Alliance is trying to establish a worldwide observance of International Forgiveness Day. I don’t know anything about this group, other than what is posted on their web site, but their self-described mission is “to evoke the healing spirit of Forgiveness worldwide.” I don’t think they’re taking their cues from scholarly writings or scientific research on forgiveness, reconciliation, and peacemaking. Instead, it appears to be a truly grassroots movement, trying on a very small scale to encourage forgiveness not only as personal tool for overcoming anger and resentment, but also as a way of repairing relationships between individuals, communities and conflict groups.

For the past 18 years, according to their web site, they have hosted an “International Forgiveness Day” event, and today is no exception. So if you’re out in the Bay Area today, and are curious, you might consider getting out to San Rafael to see what they’re up to. Also, their web site indicates that they will be live-streaming the event here, so I suppose you could celebrate remotely from your deck chair or porch swing.

But perhaps even that feels like more effort than the heat will permit you to expend. I sympathize. If that’s the case, consider sparing a thought for forgiveness today. Or raise two cheers for forgiveness. Or why not make a forgiveness day gazpacho? (This is my plan.) I can think of many worse things to celebrate on a slow, muggy Sunday in August.

The Real Roots of Vengeance and Forgiveness

Yesterday, somebody pointed me to this article, which I wrote a few years ago for a magazine called Spirituality and Health. I had not realized until yesterday that the magazine had made the article available on the web. Even though it’s several years old, I still like the way it reads. In fact, it’s as decent a précis of my book Beyond Revenge as you’re going to find anywhere.

I’m not exactly a regular reader of this particular magazine, but their editorial staff have taken an interest in some of my research and writing over the years, including some of our (by which I mean, my and my collaborators’) work on forgiveness and gratitude, for which I have always been appreciative. The founder of the magazine, whom I was fortunate enough to know, was T. George Harris–one of the most colorful figures in the history of 20th-century magazine publishing. Some readers of this blog might know of George’s work in helping to turn Psychology Today into the behemoth it eventually became, but there is much more to George’s personal and professional life that’s worth knowing about.

George died last year at the age of 89. I found two really nice chronicles of his life–this one from the local San Diego paper (George was a La Jolla resident), and this one written by Stephen Kiesling, who not only is the editor-in-chief at Spirituality and Health, but also was one of George’s closest friends and fondest admirers.

 

The Trouble with Oxytocin, Part III: The Noose Tightens for The Oxytocin–>Trust Hypothesis

https://i0.wp.com/media-cache-ak0.pinimg.com/736x/2b/1f/9b/2b1f9b4e930d47f31b1f7f3aecd0b0cf.jpgMight be time to see about having that Oxytocin tattoo removed…

When I started blogging six months ago, I kicked off Social Science Evolving with a guided tour of the evidence for the hypothesis that oxytocin increases trusting behavior in the trust game (a laboratory workhorse of experimental economics). The first study on this topic, authored by Michael Kosfeld and his colleagues, created a big splash, but most of the studies in its wake failed to replicate the original finding. I summarized all of the replications in a box score format (I know, I know: Crude. So sue me.) like so:

Box Score_Dec2013By my rough-and-ready calculations, at the end of 2013 there were about 1.25 studies’ worth of successful replications of the original Kosfeld results, but about 3.75 studies’ worth of failed replications (see the original post for details). Even six months ago, the empirical support for the hypothesis that oxytocin increases trust in the trust game was not looking so healthy.

I promised that I’d update my box score as I became aware of new data on the topic, and a brand new study has just surfaced. Shuxia Yao and colleagues had 104 healthy young men and women play the trust game with four anonymous trustees. One of those four trustees (the “fair” trustee) returned enough of the subject’s investment to cause the subject and the trustee to end up with equal amounts of money; the other three trustees (designated as the “unfair players”) declined to return any money to the subject at all.

Next, subjects were randomly assigned to receive either the standard dose of intranasal oxytocin, or a placebo. Forty-five minutes later, participants were told that they would receive an instant message from the four players to whom they had entrusted money during the earlier round of the trust game. The “fair” player from the earlier round, and one of the “unfair” players, sent no message at all. The second unfair player sent a cheap-talk sort of apology, and the third unfair player offered to make a compensatory monetary transfer to the subject that would make their payoffs equal.

Finally, study participants took part in a “surprise” round of the trust game with the same four strangers. The researchers’ key question was whether the subjects who had received oxytocin would behave in a more trusting fashion toward the four players from Round 1 than the participants who received a placebo instead.

They didn’t.

In fact, the only hint that oxytocin did anything at all to participants’ trust behaviors was a faint statistical signal that oxytocin caused female participants (but not male participants) to treat the players from Round 1 in a less trusting way. If anything, oxytocin reduced women’s trust. I should note, however, that this females-only effect for oxytocin was obtained using a statistically questionable procedure: The researchers did not find a statistical signal of an interaction between oxytocin and subjects’ sex, and without such a signal, their separation of the men’s and the women’s data for further analyses really wasn’t licensed. But regardless, the Yao data fail to support the idea that oxytocin increases trusting behavior in the trust game.

It’s time to update the box score:

Box_Score_Jun2014

In the wake of the original Kosfeld findings, 1.25 studies worth of results have accumulated to suggest that oxytocin does increase trust in the trust game, but 4.75 studies worth of results have accumulated to suggest that it doesn’t.

It seems to me that the noose is getting tight for the hypothesis that intransasal oxytocin increases trusting behavior in the trust game. But let’s stay open-minded a while longer. As ever, if you know of some data out there that I should be including in my box score, please send me the details. I’ll continue updating from time to time.

Of Crackers and Quackers: Human-Duck Social Interaction is Regulated by Indirect Reciprocity (A Satire)

1280px-221_Mallard_DuckWatching the ducks on a neighborhood pond can be an entertaining and rewarding pastime. I myself, along with my nine-year-old co-investigator, have taken daily opportunities to feed some ducks on a nearby pond over the past several months. In doing so, we not only had fun but also managed to conduct some urban science that led us to a new scientific discovery: Mallards (Anas platyrhynchos L.) engage in indirect reciprocity with humans. Scientists have known for decades, of course, that indirect reciprocity was critical to the evolution of human social interaction in large-scale societies, but we believe we are the first to identify indirect reciprocity at work in human-duck social interaction.

Here’s how we made this discovery.

On random days, we take a soda cracker along with us to feed to a single lucky duck. On the other days, we take our walks without a cracker. What my young co-investigator and I have noticed is that on cracker days, after we’ve fed the cracker to the first duck that approaches us (the “focal duck,” which we also call “the recipient”), other ducks (which we call “entertainment ducks,” or “indirect reciprocators”) appear to take notice of our generosity toward the recipient. Almost immediately, the indirect reciprocators start to perform all sorts of entertaining behaviors: They swim toward us eagerly, they waddle up to us enthusiastically, they stare at us with their dead, obsidian eyes, they quack imploringly. It’s all very amusing and my co-investigator and I have a great time. Take note of the fact that we always bring only a single cracker with us on cracker days. As a result, the indirect reciprocators have absolutely nothing to gain from the entertainment they provide. In fact, they actually incur costs (in the form of energy expended and lost foraging time) when they do so. Thus, their indirect reciprocity behavior is altruistic.

Our experience with the indirect reciprocators is very different on non-cracker days. If a focal duck comes up to us on a non-cracker day, there’s just no cracker to be had, no matter how charming or insistent the request. Dejected, the focal duck typically waddles or paddles away within a few seconds. Now, what do you suppose the entertainment ducks do after we refuse to feed the focal duck? That’s right. They withhold their entertainment behaviors. This pattern, of course, is exactly as one would expect if the entertainment ducks were regulating their entertainment behaviors according to the logic of indirect reciprocity.

Theorists typically assume that the computational demands for indirect reciprocity to evolve are quite extensive. For instance, indirect reciprocators need to possess computational machinery that enables them to acquire information about the actions of donors—either through direct sensory experience of donor-recipient interactions, or (more rarely) language-based gossip, or (even more rarely) social information stored in an external medium, such written records or the reputational information that’s often available in online markets. Indirect reciprocators also need be able to tag donors’ actions toward recipients as either “beneficial” or “non-beneficial,” store that social information in memory, and then feed that information to motivational systems that can produce the indirect reciprocity behaviors that will serve as rewards to donors. However, the indirect reciprocity we’ve identified in our mallards suggests that those computational requirements may be fulfilled in vertebrates more commonly than theorists originally thought.

Neither of us could figure out for sure whether the focal ducks were transmitting information about our generosity/non-generosity to the indirect reciprocators through verbal (or non-verbal) communication, but we think it is unlikely. Instead, we suspect that the indirect reciprocators were directly observing our behavior and then using that sensory information to regulate their indirect reciprocity behavior.

In support of this interpretation, we note that on several cracker days, it was not only other ducks that engaged us as indirect reciprocators, but individuals from two different species of turtles (which we believe to be Rachemys scripta and Apalone ferox) as well. The turtles’ indirect reciprocity behaviors, of course, were different from those of the ducks, due to differences in life history and evolutionary constraints: The turtles didn’t reward our generosity through waddle-based or quack-based rewarding, but rather, by (a) rooting around in the mud where the focal duck had received the cracker earlier, and (b) trying to grab the focal duck by the leg and drag it to a gruesome, watery death. The fact that turtles engaged in their own forms of indirect reciprocity suggests that they, at least, were obtaining information about our generosity via direct sensory experience, rather than through duck-turtle communication or written or electronic records: It is widely accepted, after all, that turtles don’t understand Mallardese or use eBay.

The involvement of turtles as indirect reciprocators also suggests that indirect reciprocity might be even more prevalent–and more complex–than even we originally suspected. Not only does indirect reciprocity evolve to regulate interactions within species (viz., Homo sapiens), and between species (viz., between Homo sapiens and Anas platyrhynchos L., as we have documented here), but also among species (Homo sapiens as donors, Anas platyrhynchos L. as recipients, and Rachemys scripta and Apalone ferox as indirect reciprocators).

Finally, we should point out that although our results are consistent with the indirect reciprocity interpretation that we have proffered here, other interpretations are possible as well. We look forward to new work that can arbitrate between these two accounts (and perhaps others). We also see excellent opportunities for simulation studies that can shed light on the evolution of indirect reciprocity involving interactions between two or even three different species, which my co-Investigator thinks she might pursue after she has mastered long division.

h/t Eric P.

Why Do Honor Killings Defy the First Law of Homicide? And Will Smaller Families Lead to Fewer Of Them?

Few categories of human rights violations more deeply scandalize the liberal (with a little-L) moral sensibility than honor killings do. Reliable numbers are hard to come by, but by most credible accounts it seems likely that several thousand Muslim women each year (and more than a few men) are stoned, burned, hanged, strangled, beheaded, stabbed, or shot to death for the sins of getting raped, falling in love, or dressing immodestly. But to anyone who thinks about human behavior from an evolutionary point of view, honor killings are not just morally outrageous: They’re also really puzzling.

As Martin Daly and Margo Wilson documented in their marvelous book Homicide, killers are very rarely the genetic relatives of their victims. Instead, they’re most often strangers, or rivals, or cuckolded lovers (who, of course, are not each others’ kin even if married—at least, not in the sense that matters to natural selection). Indeed, the typically low level of kinship between the victims of homicides and the people who kill them is so predictable that we could get away with calling it “The First Law of Homicide.” When two genetic relatives are involved in a homicide, it’s usually either as co-victims or co-perpetrators, not as victim and perpetrator.

In a sense, a general reluctance to harm or kill one’s genetic relatives is not exactly breaking news. We’ve understood since William Hamilton’s 1963 and 1964 papers that natural selection creates organisms that appear designed to maximize their inclusive fitness (which incorporates the reproductive success of the individual in whom the gene is physically located, as well as the reproductive success of other individuals who are carrying copies of that gene around) rather than their simple direct fitness. Genes “want” to maximize the total number of copies of themselves that are floating around in the world, even if some of those copies are located in other individuals’ gonads. The principle of kin selection virtually guarantees that we’re walking around with instincts that restrain us from harming our relatives, even when they’ve irritated us. To be clear, I’m not saying people never kill their kin (mental illness is a real wild card here), but the fitness disincentives of doing so were so high as our psychology was evolving that the perceived incentives to do so now have to be very high indeed.

Which is what makes honor killings so puzzling. In a recent article, Andrzej Kulczycki and Sarah Windle summarized data on the circumstances behind more than 300 honor killings across Northern Africa and the Middle East. What jumps off the page when you look at their data is how flagrantly honor killings flout the First Law of Homicide: About three-quarters of honor killings are carried out by family members of the victim. To be specific, the victims’ brothers carry out 29% of them, fathers and (to a much lesser extent, mothers), carry out about 25%, and “other male relatives” carry out an additional 19% of them. (Of the remaining 25%, virtually all are carried out by the victims’ husbands/ex-husbands.)

I’m really interested in that 75% that violate the First Law of Homicide. For the perpetrators of honor killings to over-ride their intuitive aversions to killing their own daughters or sisters, the perceived costs of “dishonor” must be very high indeed. We can’t precisely measure the exact fitness value of honor for someone who lives in a so-called culture of honor, of course, but the link between fitness and honor is undeniable. If you live in an honor culture, your honor determines your (and your children’s) job prospects, marriage prospects, ability to recruit help from neighbors, ability to secure a loan, and protection against those who would otherwise do you harm. Honor is an insurance policy, a social security check, and a glowing letter of recommendation rolled into one bundle. The fitness costs of tarnished honor in an honor culture can be steep.

One of the things I came to appreciate about honor while doing research for one of my books is that honor is a sacred commodity. It doesn’t follow the laws we expect actual physical stuff to obey, or the normal laws of economics, or even the normal rules that govern our everyday psychology. It follows the laws of Sacred Things. If you feel sad one day, you can be pretty sure that the feeling won’t last forever. Dishonor doesn’t work like that. Dishonor doesn’t wash off or fade away with time. Dishonor has to be purged or atoned for. More importantly for my argument here, dishonor does not dilute. The dishonor that a “dishonorable” behavior creates for a family is not like a fixed quantity of scarlet paint that can be used to make only a finite number of scarlet letters. When a young woman “dishonors” her family, there’s enough dishonor to thoroughly cover every one of her brothers and sisters, no matter how many brothers and sisters she has.

There’s an interesting prediction waiting in the wings. If I’m right that dishonor does not dilute, then the perceived fitness-associated costs of a single act of dishonor will be larger for a father and mother with many children than for a father and mother with only with only a few children. This has implications for reducing honor killings. Let me illustrate with a thought experiment.

The Costs of Dishonor to a Father Are Higher in Large Families

Say I am a father with nine children and one of my daughters has done something (or, more likely, has had something done to her) that has brought dishonor upon herself and each of her eight siblings. (Believe me, I am more appalled by having to write sentences like these than you are by having to read them, but I can’t come up with a better way to think through these issues than to try to step into the shoes of someone who is actually factoring honor-related concerns into their social decision-making). As the father of these nine children, the dishonored daughter has reduced my fitness by 9d because each of my children will suffer an honor-related fitness cost of d. (It might be better to quantify the hit to my fitness as 9 * .5 = 4.5 because my genetic relatedness to my children with respect to a rare allele that I possess is 0.5 rather than 1.0, but that won’t change anything in what’s to come. Can we please agree to work with 9 so as to make the math prettier?) So, if I am a father of nine children, and I can restore my family’s honor by murdering my dishonored daughter, I can recover 8d units of fitness (by restoring the damaged honor of my other eight children), and it costs me (I know, the thought sickens me as well) the fitness decrement I suffer through murdering one of my offspring.

If, on the other hand, I have only two children, then the perceived fitness cost of my daughter’s dishonor is 2d (a cost of d is imputed to both of my children), and I’d only be able to recover 1d unit of fitness (for my remaining, unmurdered child) by murdering the dishonored daughter. So, for a father with only two children, the calculus is not so clear: Am I better off in the long run to have two children whose honor is tarnished, or only one child whose honor is restored? For any plausible value of d, it’s hard to imagine that the decision-making scales would tilt in favor of killing the dishonored daughter if doing so would leave you with only one child. I’m betting that the father of two will stay his hand under circumstances in which the father of nine might not.

If I’m right about this, then a demographic shift toward smaller families in developing societies could eventually help to solve the problem of honor killings. I couldn’t find any direct evidence to support this prediction, but Manuel Eisner and Lana Ghuneim recently published a study in which they surveyed 856 Jordanian adolescents from 14 different schools to examine the predictors of their attitudes toward honor killings. They found that even when they controlled for the students’ sex (male vs. female), their religion (Muslim vs. non-Muslim), whether their mothers worked outside of the home (a good proxy for modernization), and the parents’ educational levels (also a good proxy for modern thinking), children with four or more siblings had more favorable attitudes toward honor killings than did children with three or fewer siblings. Not an exact test of my prediction, but to the extent that kids adopt their parents’ views, it seems to me that these results are at least tantalizingly consistent.

Do the human rights groups that want to reduce honor killings and other kinds of honor-related violence around the world ever talk about family size as a truly exogenous (and, in principle, modifiable) cause of honor killings? People are pinning their hopes for solving so many other problems around the world on reductions in family size, so perhaps I’m not being too pie-in-the-sky to add “reductions in honor-related violence” to that list of “Ways In Which We’d Be Better Off If People Had Fewer Kids.” As families shrink, I’m guessing that spared lives become subjectively more valuable than restored family honor.