Tag Archives: Evolutionary Psychology

Hunger: The “Proverbial” Emotion?

“The soul that is full loathes honey, but to a hungry soul, any bitter thing is sweet.”

We don’t know who authored this little proverb (which comes from the Bible’s Book of Proverbs), but you’ve got to hand it to whoever it was: he was a keen observer of human psychology. Hunger, he noticed, doesn’t simply motivate our souls to get off the couch and go find something to eat; instead, it changes our psychological relationship to food. When we’re hungry, he noted, we lower our standards: even the nasty bits are magically transformed into delicacies.

Our quality standards will sink so low when we’re hungry, in fact, that we’re even willing to eat foods that are bitter. Ordinarily, humans tend to dislike things that taste bitter because bitterness often indicates that the food we’re eating (it’s typically a plant) contains toxins whose very function is to prevent us from eating it: The plants don’t want to be eaten, and the bitter taste deters us from doing exactly that.* Hunger says, “Look. You’re starving. What difference is a little bit of plant toxin going to make? Eat that bitter thing today. You can do your detox diet tomorrow.”

What exactly is hunger? It goes without saying that hunger is a psychological state that deals with a discrete problem of survival and reproduction—your body is low on the energy it needs to keep itself running, and you won’t stay alive if your body stops running, and you can’t reproduce if you aren’t alive. Fine, but what kind of thing is it? Although many emotion researchers have been coy about saying it out loud, hunger is starting to look an awful lot like an emotion—at least on the view of emotions that evolutionary psychologists tend to favor.

Articulating a widely accepted evolutionary-psychology view of emotions, the psychologists Laith al-Shawaf and David Lewis defined emotions as “coordinating mechanisms whose evolved function is to coordinate a variety of programs in the mind and body in the service of solving a specific adaptive problem.” As examples of prototypical emotions, Al-Shawaf and Lewis point to fear (which directs a variety of physiological, behavioral, and cognitive responses that help to keep us away from dangerous things), disgust (which directs a variety of physiological, behavioral, and cognitive responses that help to keep us away from infectious things), and sexual arousal (which directs a variety of physiological, behavioral, and cognitive responses that help to direct us, as they put it, toward “advantageous mating opportunity[ies].”

So why not count hunger among them? Well, why not indeed? In another paper, Laith posited as much when he defined hunger as “a mechanism that coordinates the activity of psychological processes in the service of solving the adaptive problem of acquiring food.” And here, I think he was right on the money: If all things that are “coordinating mechanisms whose evolved function is to coordinate a variety of programs in the mind and body in the service of solving a specific adaptive problem,” and hunger is “a mechanism that coordinates the activity of psychological processes in the service of solving the adaptive problem of acquiring food,” then hunger is an emotion, is it not?

Although the evolutionary psychologist’s view that hunger is an emotion puts them (I think) in the minority of emotion researchers, there are other scientists who think of hunger in a very similar manner. The neuroscientist E.T. Rolls has conceptualized hunger as what neuroscientists call a gate. When the hunger gate senses that the body is in a depleted nutritional state, it turns the bare sensory information that we pick up from the tastes, sights, smells, and textures of foods into behavioral mandates. When the gate is closed, “the soul loathes honey.” When it’s open, “any bitter thing is sweet.” Indeed, researchers have now found the gene-regulator that opens and closes the hunger gate in the roundworm C. elegans (which is probably the most studied organism in the history of biology). It’s plausible that a similar molecular signaling system functions as a hunger gate for humans as well.

What psychological and physiological “programs” does hunger coordinate? Probably quite a few. Laith provides a long list of hunger’s miraculous powers (including some that are supported by existing research and others that are more speculative, requiring further research). Hunger, he ventures, influences perception (the bare sensory properties of foods, such as their sights and smells, lead us, gate-style, to craving or pleasure rather than indifference), attention (we notice food-related stimuli that we otherwise would ignore), problem-solving (we automatically start sorting through our options for finding food) categorization (we begin to automatically categorize things in the world as either “food” or “not food”), and memory (we find it easier to recall the locations of food items).

Support for these hypotheses is rolling in. In research that came out recently, scientists found that hunger makes food odors more attractive. Another team of researchers recently found that hunger makes Dutch undergraduate students more willing to eat novel foods such as African cucumber, fried snake, crocodile meat, kangaroo thigh, and the notoriously tastes-delicious-but-smells-like-sewage fruit known as the durian.

Effects like these bear witness to hunger’s long reach into our bodies, our thoughts, our feelings, and our behaviors. If the aphorist who wrote Proverbs 27:7 were alive today, and he could spare a day from scrawling down universal human wisdom in order to read up on the evolutionary psychology of hunger, perhaps he would write a follow-up proverb:

“Hunger gates incoming food-related sensory information into physiological responses, psychological states, and behavioral propensities that evolved for the function of re-uniting our bodies with nutrients.”

Or not. Either way, it’s fun to imagine that guy, probably wearing a flowing robe or something, hunched over his computer while he scrolls through Google Scholar with one hand and grips a massive, stinky durian with the other.


*Yes, as a matter of fact; I am aware that coffee, collards, and cocoa are bitter, along with many other things that are nice to eat and drink. There may be an adaptive reason why we’re attracted to bitterness in some cases—and it turns out those cases are the exceptions that prove the rule. But that’s a story for another day.

Behavioral Altruism is an Unhelpful Scientific Category

Altruism has been a major topic in evolutionary biology since Darwin himself, but altruism (the word) did not appear even once in Darwin’s published writings.[1] The omission of altruism from Darwin’s thoughts about altruism is hardly surprising: Altruism had appeared in print for the first time only eight years before The Origin of Species. The coiner was a Parisian philosopher named Auguste Comte.

Capitalizing on the popularity he had already secured for himself among liberal intellectuals in both France and England, Comte argued that Western civilization needed a complete intellectual renovation, starting from the ground up. Not one to shrink from big intellectual projects, Comte set out to do this re-vamping himself, resulting in four hefty volumes. Comte’s diagnosis: People cared too much for their own welfare and too little for the welfare of humanity. The West, Comte thought, needed a way of doing society that would evoke less égoisme, and inspire more altruisme.

Comte saw a need for two major changes. First, people would need to throw out the philosophical and religious dogma upon which society’s political institutions had been built. In their place, he proposed we seek out new principles, grounded in the new facts emerging from the new sciences of the human mind (such as the fast-moving scientific field of phrenology), human society (sociology), and animal behavior (biology).

Second, people would need to replace Christianity with a new religion in which humanity, rather than the God of the Abrahamic religions, was the object of devotion. In Comte’s new world, the 12-month Gregorian calendar would be replaced with a scientifically reformed calendar consisting of 13 months (each named after a great thinker from the past—for example, Moses, Paul the Apostle, Gutenberg, Shakespeare, and Descartes) of 28 days each (throw in a “Day of the Dead” at the end and you’ve got your 365-day year). Also, the Roman Catholic priesthood would be replaced with a scientifically enlightened, humanity-loving “clergy” with Comte himself—no joke—as the high priest.

Comte’s proposals for a top-down re-shaping of Western society didn’t get quite the reception he was hoping for (though they caught on better than you might think: If you’re ever in Paris or Rio, pay a visit to the Temples of Humanity that Comte’s followers founded around the turn of the 19th century). In England especially, the scientific intelligentsia’s response was frosty. On the advice of his friend Thomas Huxley, Darwin also steered clear of all things Comtean, including altruism.

Nevertheless, altruism was in the air, and its warm reception among British liberals at the end of the 19th century is how the word percolated into everyday language. It’s also why the word is still in heavy circulation today. The British philosopher Herbert Spencer, an intellectual rock star of his day, was a great admirer of Comte, and he played a major role in establishing a long-term home for altruism in the lexicons of biology, social science, and everyday discourse.[2] Spencer used the term altruism in three different senses—as an ethical ideal, as a description of certain kinds of behavior, and as a description for a certain kind of human motivation. (He wouldn’t have understood how to think about it as an evolutionary concept.)[3]

Here, I want to look at Spencer’s second use of the word altruism—as a description of a class of behaviors—because I think it is a deeply flawed scientific concept, despite its wide usage. At the outset, I should note that as a Darwinian concept—an evolutionary pathway by which natural selection can create complex functional design by building traits in individuals that cause them to take actions that increase the rate of replication of genes locked inside their genetic relatives’ gonads—altruism has none of the conceptual problems that behavioral altruism has.

With Spencer’s behavioral definition of altruism, he meant to refer to “all action which, in the normal course of things, benefits others instead of benefiting self.”[4] A variant of this definition is embraced today by many economists and other social scientists, who use the term behavioral altruism to classify all “costly acts that confer benefits on other individuals.”[5] Single-celled organisms are, in principle, as capable of Spencerian behavioral altruism as humans are. Social scientists who subscribe to the behavioral definition of altruism have applied it to a wide range of human behaviors. Have you ever jumped into a pool to save a child or onto a hand grenade to spare your comrades? Donated money to your alma mater or a charity? Given money, a ride, or directions to a stranger? Served in the military? Donated blood, bone marrow, or a kidney? Reduced, re-used, or recycled? Adopted a child? Held open a door for a stranger? Shown up for jury duty? Volunteered for a research experiment? Taken care of a sick friend? Let someone in front of you in the check-out line at the grocery store? Punished or scolded someone for breaking a norm or for being selfish? Taken found property to the lost and found? Tipped a server in a restaurant in a city you knew you’d never visit again? Pointed out when a clerk has undercharged you? Lent your fondue set or chain saw to a neighbor? Shooed people away from a suspicious package at the airport? If so, then you, according to the behavioral definition, are an altruist.[6]

Some economists seek to study behavioral altruism in the laboratory with experimental games in which researchers give participants a little money and then measure what they do with it. The Trust Game, which involves two players, is a great example. We can call the first actor an Investor because he or she is given a sum of money—say, $10—by the experimenter, some or all of which he or she can send to the other actor, whom we might call the trustee. The investor knows that every dollar he or she entrusts to the trustee gets multiplied by a fixed amount—say, 3—so if the investor transfers $1 to the trustee, the trustee now has $3 more in his or her account as a result of the investor’s $1 transfer. Likewise, the investor knows that the trustee will subsequently decide whether to transfer some money back. Under these circumstances, according to some experimental economists, if the Investor sends money to the Trustee, it is “altruistic” because it is a “costly act that confers an economic benefit upon another individual.”[7] But the lollapalooza of behavioral altruism doesn’t stop there: It’s also altruistic, per the behavioral definition that economists embrace, if the Trustee transfers money back to the Investor. Here, too, one person is paying a cost to provide a benefit to another person.

Notice that motives don’t matter for behavioral altruism. (To social psychologists like Daniel Batson, altruism is a motivation to raise the welfare of another individual, pure and simple. Surprising as it might seem, this is also, in fact a conceptually viable scientific category. But that’s another blog post.) All that matters for a behavior to be altruistic is that it entails costs to actors and benefits to recipients. Clearly, donating a kidney or donating blood are costly to the donor and beneficial to the recipients, but even when you hold a door open for a stranger, you pay a cost (a few seconds of your time and a calorie or so worth of physical effort) to deliver a benefit to someone else. By this definition, even an insurance company’s agreement to cover the MRI for your (possibly) torn ACL qualifies: After all, the company pays a cost (measured in the thousands of dollars) to provide you with a benefit (magnetic confirmation either that you need surgery or that your injury will probably get better after a little physical therapy).

But a category that lumps together recycling, holding doors for strangers, donating kidneys, serving in the military, and handing money over to someone in hopes of securing a return on one’s investment—simply because they all involve costly acts that confer benefits on others—is a dubious scientific category. Good scientific categories, unlike “folk categories,” are natural kinds—as Plato said, they “carve nature at its joints.” Rather than simply sharing one or more properties that are interesting to a group of humans (for example, social scientists who are interested in a category called “behavioral altruism”), they should share common natural essences, common causes, or common functions. Every individual molecule with the chemical formula H2O is a member of a natural kind—water—because they all share the same basic causes (elements with specific atomic numbers that interact through specific kinds of bonds). These deep properties are the causes of all molecules of H2O that have ever existed and that ever will exist. Natural kinds are not just depots for things that have some sort of gee-whiz similarity.[8]

If behavioral altruism is a natural kind, then knowing that a particular instance of behavior is “behaviorally altruistic” should enable me to draw some conclusions about its deep properties, causes, functions, or effects. But it doesn’t. All I know is that I’ve done something that meets the definition of behavioral altruism. Even though I have, on occasion, shown up for jury duty, held doors open for strangers, received flu shots, loaned stuff to my neighbors, and even played the trust game, simply knowing that they are all instances of “behavioral altruism” does not enable me to make any non-trivial inferences about the causes of my behavior. By the purely behavioral definition of altruism, I could show up for jury duty to avoid being held in contempt of court, I could give away some old furniture because I want to make some space in my garage, and I could hold the door for someone because I’m interested in getting her autograph. The surface features that make these three behaviors “behaviorally altruistic” are, well, superficial. Knowing that they’re behaviorally altruistic gives me no new raw materials for scientific inference.

So if behavioral altruism isn’t a natural kind, then what kind of kind is it? Philosophers might call it a folk category, like “things that are white,” or “things that fit in a bread box,” or “anthrosonic things,” which comprise all of the sounds people can make with their bodies—for example, hand-claps, knuckle- and other joint-cracking, the lub-dub of the heart’s valves, the pitter-patter of little feet, sneezes, nose-whistles, coughs, stomach growls, teeth-grinding, and beat-boxing. Anthrosonics gets points for style, but not for substance: My knowing that teeth-grinding is anthrosonic does not enable me to make any new inferences about the causes of teeth-grinding because anthrosonic phenomena do not share any deep causes or functions.

Things that are white, things that can fit in a bread box, anthrosonics, things that come out of our bodies, things we walk toward, et cetera–and, of course, behavioral altruism–might deserve entries in David Wallechinsky and Amy Wallace’s entertaining Book of Lists[9], but not in Galileo’s Book of Nature. They’re grab-bags.


[1] Dixon (2013).
[2] Spencer (1870- 1872, 1873, 1879).
[3] Dixon (2005, 2008, 2013).
[4] Spencer (1879), p. 201.
[5] Fehr and Fischbacher (2003), p. 785.
[6] See, for instance, Silk and Boyd (2010), Fehr and Fischbacher (2003); Gintis, Bowles, Boyd, & Fehr (2003).
[7] Fehr and Fischbacher (2003), p. 785.
[8] Slater and Borghini (2011).
[9] Wallechinsky, Wallace, and Wallace (2005).


Dixon, T. (2005). The invention of altruism: August Comte’s Positive Polity and respectable unbelief in Victorian Britain. In D. M. Knight & M. D. Eddy (Eds.), Science and beliefs: From natural philosophy to natural science, 1700-1900 (pp. 195-211). Hampshire, England: Ashgate.

Dixon, T. (2008). The invention of altruism: Making moral meanings in Victorian Britain. Oxford, UK: Oxford University Press.

Dixon, T. (2013). Altruism: Morals from history. In M. A. Nowak & S. Coakley (Eds.), Evolution, games, and God: The principle of cooperation (pp. 60-81). Cambridge, MA: Harvard University Press.

Fehr, E., & Fischbacher, U. (2003). The nature of human altruism. Nature, 425, 785-791.

Gintis, H., Bowles, S., Boyd, R., & Fehr, E. (2003). Explaining altruistic behavior in humans. Evolution and Human Behavior, 24, 153-172.

Silk, J. B., & Boyd, R. (2010). From grooming to giving blood: The origins of human altruism. In P. M. Kappeler & J. B. Silk (Eds.), Mind the gap: Tracing the origins of human universals (pp. 223-244). Berlin: Springer Verlag.

Slater, M. H., & Borghini, A. (2011). Introduction: Lessons from the scientific butchery. In J. K. Campbell, M. O’Rourke, & M. H. Slater (Eds.), Carving nature at its joints: Natural kinds in metaphysics and science (pp. 1-31). Cambridge, MA: MIT Press.

Spencer, H. (1870- 1872). Principles of psychology. London: Williams and Norgate.

Spencer, H. (1873). The study of sociology. London: H. S. King.

Spencer, H. (1879). The data of ethics. London: Williams and Norgate.

Wallechinsky, D., & Wallace, A. (2005). The book of lists: The original compendium of curious information. Edinburgh, Scotland: Canongate Books.

A P-Curve Exercise That Might Restore Some of Your Faith in Psychology

I teach my university’s Graduate Social Psychology course, and I start off the semester (as I assume many other professors who teach this course do) by talking about research methods in social psychology. Over the past several years, as the problems with reproducibility in science have become more and more central to the discussions going on in the field, my introductory lectures have gradually become more dismal. I’ve come to think that it’s important to teach students that most research findings are likely false, that there is very likely a high degree of publication bias in many areas of research, and that some of our most cherished ideas about how the mind works might be completely wrong.

In general, I think it’s hard to teach students what we have learned about the low reproducibility of many of the findings in social science without leaving them with a feeling of anomie, so this year, I decided to teach them how to do p-curve analyses so that they would at least have a tool that would help them to make up their own minds about particular areas of research. But I didn’t just teach them from the podium: I sent them away to form small groups of two to four students who would work together to conceptualize and conduct p-curve analysis projects of their own.

I had them follow the simple rules that are specified in the p-curve user’s guide, which can be obtained here, and I provided a few additional ideas that I thought would be helpful in a one-page rubric. I encouraged them to make sure they were sampling from the available population of studies in a representative way. Many of the groups cut down their workload by consulting recent meta-analyses to select the studies to include. Others used Google Scholar or Medline. They were all instructed to follow the p-curve manual chapter-and-verse, and to write a little paper in which they summarized their findings. The students told me that they were able to produce their p-curve analyses (and the short papers that I asked them to write up) in 15-20 person-hours or less. I cannot recommend this exercise highly enough. The students seemed to find it very empowering.

This past week, all ten groups of students presented the results of their analyses, and their findings were surprisingly (actually, puzzlingly) rosy: All ten of the analyses revealed that the literatures under consideration possessed evidentiary value. Ten out of ten. None of them showed evidence for intense p-hacking. On the basis of their conclusions (coupled with the conclusions that previous meta-analysts had made about the size of the effects in question), it does seem to me that there really is license to believe a few things about human behavior:

(1) Time-outs really do reduce undesirable behavior in children (parents with young kids take notice);

(2) Expressed Emotion (EE) during interactions between people with schizophrenia and their family members really does predict whether the patient will relapse in in the successive 9-12 months (based on a p-curve analysis of a sample of the papers reviewed here);

(3) The amount of psychological distress that people with cancer experience is correlated with the amounts of psychological distress that their caregivers manifest (based on a p-curve analysis of a sample of the papers reviewed here);


(4) Men really do report more distress when they imagine their partners’ committing sexual infidelity than women do (based on a p-curve analysis of a sample of the papers reviewed here; caveats remain about what this finding actually means, of course…)

I have to say that this was a very cheering exercise for my students as well as for me. But frankly, I wasn’t expecting all ten of the p-curve analyses to provide such rosy results, and I’m quite sure the students weren’t either. Ten non-p-hacked literatures out of ten? What are we supposed to make of that? Here are some ideas that my students and I came up with:

(1) Some of the literatures my students reviewed involved correlations between measured variables (for example, emotional states or personality traits) rather than experiments in which an independent variable was manipulated. They were, in a word, personality studies rather than “social psychology experiments.” The major personality journals (Journal of Personality, Journal of Research in Personality, and the “personality” section of JPSP) tend to publish studies with conspicuously higher statistical power than do the major journals that publish social psychology-type experiments (e.g., Psychological Science, JESP and the two “experimental” sections of JPSP), and one implication of this fact, as Chris Fraley and Simine Vazire just pointed out is that the former set of experiment-friendly journals are more likely, ceteris paribus, to have higher false positive rates than is the latter set of personality-type journals.

(2) Some of the literatures my students reviewed were not particularly “sexy” or “faddish”–at least not to my eye (Biologists refer to the large animals that get the general public excited about conservation and ecology as the “charismatic megafauna.” Perhaps we could begin talking about “charismatic” research topics rather than “sexy” or “faddish” ones? It might be perceived as slightly less derogatory…). Perhaps studies on less charismatic topics generate less temptation among researchers to capitalize on undisclosed researcher degrees of freedom? Just idle speculation…

(3) The students went into the exercise without any a priori prejudice against the research areas they chose. They wanted to know whether the literatures the focused on were p-hacked because they cared about the research topics and wanted to base their own research upon what had come before–not because they had read something seemingly fishy on a given topic that gave them impetus to do a full p-curve analysis. I wonder if this subjective component to the exercise of conducting a p-curve analysis is going to end up being really significant as this technique becomes more popular.

If you teach a graduate course in psychology and you’re into research methods, I cannot recommend this exercise highly enough. My students loved it, they found it extremely empowering, and it was the perfect positive ending to the course. If you have used a similar exercise in any of your courses, I’d love to hear about what your students found.

By the way, Sunday will be the 1-year anniversary of the Social Science Evolving Blog. I have appreciated your interest.  And if I don’t get anything up here before the end of 2014, happy holidays.

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:


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.

David Brooks Declares: “Evolutionary Biology and the Other Axis Sciences Declare War on Character and Depth!”

You know how Bill O’Reilly has made a yearly habit of declaring that the godless liberals who run America’s public institutions have declared war on Christmas? Reading David Brooks’s piece in yesterday’s (March 14, 2014) New York Times, The Deepest Self, I wondered whether Brooks had taken a page out of O’Reilly’s playbook. No, Brooks isn’t fretting about the demise of nativity scenes on courthouse lawns or bans on Have Yourself a Merry Little Christmas. Instead, Brooks is worried about the decline of character, and of depth, which he defines (a little obliquely, I think), as the possession of “permanent convictions about fundamental things…a web of unconditional loves…and permanent commitments to transcendent projects that cannot be completed in a single lifetime.

Brooks has met the enemy of character and depth: It’s a scientific axis of evil that includes “evolutionary biology” (by the way, when did “evolutionary biology” start sounding cooler to Opinion columnists than “evolutionary psychology?”), “the chemistry and biology of love and sex,” and “psychology and the cognitive sciences.” Together, these Axis scientific powers are pushing a view of human nature that is crowding “character” and “depth” out of the marketplace of ideas:

[T]he strictly evolutionary view of human nature sells humanity short. It leaves the impression that we are just slightly higher animals—thousands of years of evolutionary processes capped by a thin layer of rationality. It lops off entire regions of human possibility.

And, according to Brooks, that’s just wrong:

In fact, while we are animals, we have much higher opportunities. While we start with and are influenced by evolutionary forces, people also have the chance to make themselves deep in a way not explicable in strictly evolutionary terms.

Wow. This sounds bad indeed. Character is important! Depth is important! If evolutionary psychology and the other axis sciences are pushing a view of human nature that marginalizes character, then Brooks is right to be concerned.

But they aren’t, so Brooks isn’t.

First of all, Brooks is wrong when he accuses evolutionary psychology of drawing a profound contrast between the throbbing mass of irrational, unconscious, animalistic impulses and the thin veneer of rationality that gets slapped on top of that jumble. In his indictment, Brooks accuses evolutionary psychology and the other axis sciences of pushing the following view of human nature:

Deep in the core of our being, there are the unconscious natural processes built in by evolution. These deep unconscious processes propel us to procreate or strut or think in certain ways, often impulsively. Then, at the top, we have our conscious, rational processes. This top layer does its best to exercise some restraint and executive function…This evolutionary description has become the primary way we understand ourselves. Deep down we are mammals with unconscious instincts and drives. Up top there’s a relatively recent layer of rationality.

To me, this sounds like Brooks has mistaken Darwin for Freud. It was Freud, after all, and not Darwin, who bequeathed to us the Id, Ego, and Superego. Evolutionary psychology has bequeathed a view of the mind as an integrated set of reasoning systems that are good at solving problems that ancestral humans faced as our species was becoming modern. According to the evolutionary psychology view of mental processes, there is no mind at war with itself, but rather, a collection of systems that are integrated and interdependent, even if their agendas don’t always coincide for every possible course of action. (If they did, what would be the point in having multiple systems?) Whatever that “relatively recent layer of rationality” is, evolutionary psychology’s view of human nature suggests that it’s going to be good at doing the jobs that natural selection designed it to do, which means that it has to play nicely with the other evolved systems the mind contains.

And even though evolutionary social scientists don’t yet know for sure what those jobs are, they have some decent hypotheses. Humans in every society that has ever existed have formed friendships, sought to cultivate good reputations with their neighbors, tried to master their environments, worked to develop social and human capital (some of Brooks’s other darlings), and sought to share the wisdom they have acquired over a lifetime with old friends and loved ones. Not every human succeeds at these tasks, but most do, to varying degrees. It’s Brooks who is bifurcating human nature into a zoo of untamed, irrational, animalistic impulses and a thin layer of reason that tries, bumblingly, to play zookeeper. Don’t blame evolutionary psychology for a dichotomy between what’s animalistic/natural and what’s rational/restrained, for that’s a dichotomy that evolutionary psychology actively resists.

Second, Brooks pushes a very old and very worn-out dichotomy between “nature” and “development:”

But depth, the core of our being, is something we cultivate over time. We form relationships that either turn the core piece of ourselves into something more stable and disciplined or something more fragmented and disorderly. We begin with our natural biases but carve out depths according to the quality of the commitments we make. Our origins are natural; our depths are man-made — engraved by thought and action.

It’s always nice to have new examples of the nature/nurture fallacy to show the freshman psychology students I teach, so in a way I’m pleased to see Brooks’s fresh recapitulation of that fallacy here. The set of human traits that are natural and the set of human traits that develop over time are not mutually exclusive. In fact, the two sets overlap almost completely. The body’s ability to produce calluses, scars, and darker skin in response to sunlight are all natural. They are also all “things that develop over time.” Learning a language is natural for humans. It’s also something that happens—and something that humans can even “actively cultivate”—over time. The same goes for character. Why is it that humans strive to become better and wiser, whereas our dogs and cats and goldfish (apparently) don’t? Because the urge to develop character is part of human nature, but not part of dog nature, cat nature, or goldfish nature.

Finally—and this is just a hunch—I think Brooks is confusing evolutionary psychology’s (de facto) research agenda with evolutionary psychology’s (actual) view of human nature. What’s really bugging Brooks about evolutionary psychology, I think, is its preoccupation with “the chemistry and biology of love and sex.” The lede to his piece, after all, is a recitation of factoids (drawn, one presumes, from recent research articles) regarding the effects of humans’ sexual appetites on their behavior, perceptions, and judgments.

I get the sense that Brooks finds evolutionary psychology’s overweening emphasis on sex a little trying. On this point, I actually agree with him. Sex has become to evolutionary psychology what Fire and Rain is to a James Taylor concert. Even so, evolutionary psychologists also study things like trust, cooperation, generosity, gratitude, forgiveness, reconciliation, moral judgments, reputation, culture, reasoning, empathy, language, music, memory, the development of expertise, and even play. Are concepts like these relevant to Brooks’s definition of character? I hope so: They’re relevant to everybody else’s. Granted, you won’t find any scientific talks on “depth” at an annual meeting of the Human Behavior and Evolution Society, but can you imagine hearing anything interesting on the topic of “depth” at any scientific conference?

Brooks’s fretting strikes me as the sort of thing people write when they’re worried that science might actually succeed in explaining something important about human nature. But “explaining things” is what scientists are supposed to be doing. As Steven Pinker recently wrote, “The mindset of science [is] indispensable in all areas of human concern, including politics, the arts, and the search for meaning, purpose, and morality.” In my opinion, you can add character to Pinker’s list without reducing its accuracy in the slightest.

Brooks is obviously free to continue admiring how people acquire permanent convictions about fundamental things, webs of unconditional loves, and permanent commitments to transcendent projects that cannot be completed in a single lifetime,” but some of us actually want to understand the pillars of human character, not just ooh and ahh about them and yearn for a time when evolutionary psychology and the other axis sciences weren’t butting into conversations in which they weren’t welcome. And despite what Brooks or anybody else might lead you to believe, as far as character is concerned, evolutionary psychology is trying to make love, not war.