It's a Jungle in There: How Competition and Cooperation in the Brain Shape the Mind (35 page)

Of special interest to evolutionary psychologists are features of current psychology that are mysterious until evolution is invoked. Getting bigger tips from customers at strip clubs at fertile times is just the sort of thing that turns on evolutionary psychologists. You probably wouldn’t think of looking for this relation if you weren’t tuned in to evolutionary psychology.

Evolutionary psychologists have uncovered many intriguing results besides the ones just mentioned. They’ve found, for example, that the ratio of waist diameter to hip diameter among Playboy models has remained relatively constant over many decades, the range of values being between .67 and .80. Supposedly, this range of ratios signals optimal fertility.
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Another finding from evolutionary psychology is that if married couples split up, they’re more likely to do so after three or four years of marriage than earlier. Three to four years is when offspring are well enough along in their development that their chances of survival are relatively secure. A mom or, more likely, a dad is likelier to split once the stats tip in favor of offspring survival, or so goes the argument.
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Within cognitively oriented evolutionary psychology, some research suggests that memory may be specially tuned to what’s most marked for survival. In this connection, consider a study by James Nairne and his colleagues at Purdue University.
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They compared memory for words that were attended to in different ways by different groups of university students based on the instructions the participants were given. One group rated the words for their survival value. Their instructions were as follows:

In this task, we would like you to imagine that you are stranded in the grasslands of a foreign land, without any basic survival materials. Over the next few months, you’ll need to find steady supplies of food and water and protect yourself from predators. We are going to show you a list of words, and we would like you to rate how relevant each of these words would be for you in this survival situation. Some of the words may be relevant and others may not—it’s up to you to decide.

The words were rated from 1 (totally irrelevant) to 5 (extremely relevant). Meanwhile, other students from the same population were randomly
assigned to other groups and were asked to provide different sorts of ratings for the same words. One group rated how pleasant the words were. Another rated how easy it was to imagine the objects referred to by the words. Another group rated how well the words helped them recall personal experiences. Still another group generated words by unscrambling the initial letters and then gave the words’ pleasantness ratings. A final group simply tried to remember the words. Behind this experimental design was the experimenters’ expectation that rating the words for survival would make the words especially memorable. The expectation was borne out. Memory was better in the survival condition than in any other.

This result is impressive insofar as the other methods were known from prior research to be effective, at least as compared to testing recall on a purely incidental basis. No researcher had previously asked people to attend to words from the perspective of the words’ survival value. Nor had anyone posited that rating words for survival would make the words more or even most memorable. That these manipulations boosted recall adds credence to the view that psychology reflects evolutionary pressures.

Given this last result and the other positive findings for evolutionary psychology—just a few of which have been mentioned above—is there anything not to like about the evo-psych approach? Consider the study just mentioned. Its finding is surprising. Who would have thought that focusing on the survival value of words would make the words stick so well? The finding is impressive insofar as it withstood a challenge from the authors themselves, who speculated that some other feature of the task might have actually accounted for the better memory for the survival-rated words—specifically, the fact that survival is a more coherent theme around which to organize words than were the other dimensions used in the study. A further test dispelled that alternative.
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You might still have a reservation, though. If survival is so important, why isn’t everything
always
memorized as if life depends on it? If your brain evolved in ways that made you evolutionarily fit, then why should you need to be reminded to consider the survival value of information? You should
always
do so, for otherwise you’d be a dead duck.

Another way to frame this question is to ask how you would interpret a
failure
to find a difference between the rate-for-survival condition and the other conditions. What would it mean, in other words, if the study
didn’t
show that words are most memorable when people are told to attend to the life-or-death importance of the words? That outcome could be taken to support the view that we are well prepared to remember whatever may bear on our
chances for surviving in a dangerous world. Remembering what is pleasant or not is surely important for survival, as is remembering what can be imagined versus what cannot be, and other contrasts. Given these possibilities, you may wonder whether the results could have been interpreted as favoring evolutionary psychology no matter how they turned out.

This brings me to some other difficulties that people have had with evolutionary psychology. Those difficulties are of two general sorts. One is political. The other is scientific. The scientific concern is more germane to the main thesis here, but the political concern is worth mentioning along the way.

Politically, the problem some people have with evolutionary psychology is that they see it being used to justify or excuse practices that are ideologically ugly. The most ardent political critic of the evolutionary psychology approach is Natalie Angier, a popular-science writer whose best-known outlet is
The New York Times
. One of her
New York Times
articles was a scathing critique of the treatment of women by evolutionary psychologists.
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Her arguments were replayed in a chapter of her book
The Canon
and in a chapter of another of her books,
Woman: An Intimate Geography
.
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I admire Angier’s writing and, in case it’s not obvious to those who read Angier and have been reading me here, I emulate her style. Often, I recommend Angier’s writing to my students to help them see how good writing can be. It happens, too, that I mainly agree with her politics. As she says, it can be a self-serving excuse to say that women have the station they do because of their biology. From this biological premise, maxims like “Boys will be boys,” “Men need to have their way,” “No means yes,” and so on can become all-too-convenient slogans. “No to those slogans!” Natalie Angier insists, and I agree. Still, if evolutionary psychology has been misused by some with political or other agendas, that doesn’t mean its core scientific claims are incorrect. Nazis used principles of chemistry to gas millions (including my father’s parents), but that doesn’t mean the principles of chemistry on which they relied must be rejected.

The concern with evolutionary psychology that’s more germane to the theme of this book is scientific. It’s a concern captured by two words: “Just so.” Those words embody what’s troubling to many people about evolutionary psychology—that much or at least some of it amounts to just-so stories.

Suppose you ask an evolutionary psychologist, “Why do heterosexual men like ripe breasts and succulent lips in women?” The evolutionary psychologist might reply, “Because those features signal the capacity to bear and sire children.” “Fair enough,” you might answer. “And why do we have the rules of grammar that we do in natural language?” “Uh, well,” the
evolutionary psychologist might stammer. “Somehow those rules, or their neural or cognitive concomitants, got selected for.” “But why
those
rules?” you might continue. “Well, that’s just the way it was,” your evo-psych friend might say. If you persist, the evolutionary psychologist might stare at you in a menacing way, drawing on his or her knowledge that furrowed brows can make foes retreat. If reason won’t win the argument, maybe an aggressive display will.

Having just-so stories can try people’s patience. A few such stories are acceptable, especially if they’re practical. No one, as far as I know, fully understands why aspirin works; it just does. It’s a just-so story, which is good enough for the millions of people who take aspirin every day to relieve their aches and pains. Not knowing why some features of modern-day psychology evolved as they did, but claiming that without those features we’d not be here, doesn’t buy you very much, at least if you’re after a good predictive theory. This point was made in a blistering review of an evo-psych book
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by Alison Gopnik of the University of California, Berkeley:

[the]…conclusions from all this research are that human childhood is the result of evolution and that genetics and culture interact—conclusions that are both surely obvious to everyone but creationists in the first place. This unsatisfying quality is common to much evolutionary psychology. Either the researchers make the empty general claim that behavior evolved or they draw substantive conclusions from this claim that simply don’t follow. To say that a human behavior is adaptive or is the result of evolution tells us nothing about whether that behavior is innate or learned, universally triggered or culturally transmitted. This is because our particularly powerful ability to adapt through learning and culture, is, arguably, the most important human evolutionary advantage. For human beings, culture is our nature, and the drive to learn is our most important and fundamental instinct.
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Given such a complaint about the “outer jungle” theory of psychology, where does it leave the “inner jungle” theory offered here? Will the Alison Gopniks of the world be just as scathing in their condemnation of the inner-jungle idea? Will they, so to speak, “kill me off”? There are several reasons why they shouldn’t, quite apart from the fact that I hope they won’t.

First, the scale of time and space over which the inner-jungle principle is pursued is more restricted than the scale of time and space over which the outer-jungle theory (evolutionary psychology) is pursued. It’s easier to trace the history of individuals than to trace the history of thousands of long-lost
relatives stretching back millennia. You’re on safer ground trying to say how a particular form of behavior or knowledge took hold in one person or in one animal than in an entire species.

Second, the inner-jungle principle isn’t especially concerned with establishing whether a given trait or bit of knowledge is inborn or learned. Evolutionary psychologists tend to be nativists, looking for inherited proclivities. I too believe that there are built-in tendencies that, among other things, favor some concepts over others, notably in the domains of language, numbers, elementary physics, and basic social interaction. Evidence for these tendencies has been obtained through laboratory studies.
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Anyone who still sanctions the idea that we are born as blank slates is out of touch with modern research.
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On the other hand, apropos of the just-so woe, the inner-jungle approach shares the fault that it doesn’t make exact predictions. Absent from the theory are clear constraints for how much cooperation and competition can occur within the brain, over what scales of space and time they can occur, and so on. Some such constraints surely exist and may account for some of the critical constants of cognitive psychology, such as the number of meaningful elements that can be held in working memory: seven, plus or minus two.
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As I suggested in
Chapter 1
, the number of meaningful elements or “chunks” may be something like the number of mobsters who can run rackets in a big city or, to make a friendlier analogy, the number of close personal friends you’re likely to have. Via Facebook you might have hundreds or even thousands of “friends,” but the number of people you’re likely to be with at Thanksgiving or on your birthday or by you at your deathbed is likely to be closer to seven, plus or minus two. Which came first—the number of chunks that can be maintained in memory or the number of close friends you can have—is an interesting chicken-and-egg problem.

Just as I can’t say why the number of chunks we hold in working memory is seven plus or minus two, I can’t say why reaction times have the values they do, though as I argued in
Chapter 5
, it’s significant that those times are as long as they are and not closer to the small values they potentially could be if you just counted synapses between receptors and effectors. The magical number seven, the lengths of reaction times, how long you can retain information, and other constants are all of a piece. All these values reflect the dynamics of competition and cooperation in the brain, I believe. A challenge for future research will be to explain why these numerical values are what they are. If the magical number were 70 rather than 7, would the rate of forgetting be much different than it is and would reaction times be much longer or shorter than they tend to be?

The jungle principle is all about the birth and death of ideas in individual minds, but if the principle is truly general, it should also apply to the birth and death of ideas transmitted between individuals. In recent years it has become clear, in fact, that ideas do survive, change, and die much as organisms do. Though ideas are abstract entities, they have lives and deaths of their own, commensurate with their existing in a competitive environment.

The notion that ideas are susceptible to natural selection was advanced by Richard Dawkins in his book
The Selfish Gene
.
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In that volume, Dawkins argued that ideas and their conceptual kernels survive, mutate, and expire within and across individuals. He called these idea units
memes
. According to Dawkins, just as genes are passed on in various combinations from generation to generation, memes are passed on as well, either flourishing or dying based on their fits to the environment in which they’re expressed.