Kluge: The Haphazard Construction of the Human Mind (Houghton Mifflin; 2008)

within. Consider, for example, a study that examined how office workers, some feeling hungry, some not, would select which snack they'd like to have a week hence, in the late afternoon. Seventy-two percent of those who were hungry at the time of the decision (several days before they would be having the snack in question) chose unhealthful snacks, like potato chips or candy bars. Among the people who weren't feeling hungry, only 42 percent chose the same unhealthful snacks; most instead committed themselves to apples and bananas. Everybody knows an apple is a better choice (consistent with our long-term goal of staying healthy), but when we feel hungry, memories of the joys of salt and refined sugar win out.

All of this is, of course, a function of evolution. Rationality, pretty much by definition, demands a thorough and judicious balancing of evidence, but the circuitry of mammalian memory simply isn't attuned to that purpose. The speed and context-sensitivity of memory no doubt helped our ancestors, who had to make snap decisions in a challenging environment. But in modern times, this former asset has become a liability. When context tells us one thing, but rationality another, rationality often loses.

Evolutionary inertia made a third significant contribution to the occasional irrationality of modern humans by calibrating us to expect a degree of uncertainty that is largely (and mercifully) absent in contemporary life. Until very recently, our ancestors could not count on the success of next year's harvest, and a bird in hand was certainly better than two, or even three, in the bush. Absent refrigerators, preservatives, and grocery stores, mere survival was far less assured than it is today — in the immortal words of Thomas Hobbes, life was 'nasty, brutish, and short.'

As a result, over hundreds of millions of years, evolution selected strongly for creatures that lived largely in the moment. In every species that's ever been studied, animals tend to follow what is known as a 'hyperbolic discounting curve' — fancy words for the fact that organisms tend to value the present far more than the future. And the closer temptation is, the harder it is to resist. For example, at a remove of 10 seconds, a pigeon can recognize (so to speak) that it's worth waiting 14 seconds to get four ounces of food rather than a single ounce in 10 seconds — but if you wait 9 seconds and let the pigeon change its choice at the last moment, it will. At the remove of just 1 second, the desire for food now overwhelms the desire for more food later; the pigeon refuses to wait an extra 4 seconds, like a hungry human noshing on chips while he waits for dinner to arrive.

Life is generally much more stable for humans than for the average pigeon, and human frontal lobes much larger, but still we humans can't get over the ancestral tendency to live in the moment. When we are hungry, we gobble French fries as if driven to lard up on carbs and fat now, since we might not find any next week. Obesity is chronic not just because we routinely underexercise, but also because our brain hasn't caught up with the relative cushiness of modern life.* We continue to discount the future enormously, even as we live in a world of all-night grocery stores and 24/7 pizza delivery.

Future discounting extends well beyond food. It affects how people spend money, why they fail to save enough for retirement, and why they so frequently rack up enormous credit card debt. One dollar now, for example, simply seems more valuable than $1.20 a year hence, and nobody seems to think much about how quickly compound interest rises, precisely because the subjective future is just so far away — or so we are evolved to believe. To a mind not evolved to think about money, let alone the future, credit cards are almost as serious a problem as crack. (Fewer than 1 in 50 Americans uses crack regularly, but nearly half carry regular credit card debt, almost 10 percent owing over $10,000.)

Our extreme favoritism toward the present at the expense of the future would make sense if our life span were vastly shorter, or if the world were much less predictable (as was the case for our ancestors), but in countries where bank accounts are federally insured and grocery stores reliably restocked, the premium we place on the present is often seriously counterproductive.

The more we discount the future, the more we succumb to short-term temptations like drugs, alcohol, and overeating. As one researcher, Howard Rachlin, sums it up,

in general, living a healthy life for a period of ten years, say, is in

trinsically satisfying . . . Over a ten-year period, virtually all

^Ironically, our ability to moderate temptation increases with age, even as our life expectancy goes down. Children, who are the most likely to live into the future, are the least likely to be patient enough to wait for it.

would prefer living a healthy life to being a couch potato. Yet we

also (more or less) prefer to drink this drink than not to drink it,

to eat this chocolate sundae than to forgo it, to smoke this cigarette

than not smoke it, to watch this TV program than spend a half-

hour exercising .. . [emphasis added]

I don't think it's exaggerating to say that this tension between the short term and the long term defines much of contemporary Western life: the choice between going to the gym now and staying home to watch a movie, the joy of the French fries now versus the pain of winding up later with a belly the size of Buddha's.

But the notion that we are shortsighted in our choices actually explains only half of this modern bourgeois conflict. The other half of the story is that we humans are the only species smart enough to appreciate the fact that there is another option. When the pigeon goes for the one ounce now, I'm not sure it feels any remorse at what has been lost. I, on the other hand, have shown myself perfectly capable of downing an entire bag of the ironically named Smartfood popcorn, even as I recognize that in a few hours I will regret it.

And that too is a sure sign of a kluge: when I can do something stupid even as I know at the time that it's stupid, it seems clear that my brain is a patchwork of multiple systems working in conflict. Evolution built the ancestral reflexive system first and evolved systems for rational deliberation second — fine in itself. But any good engineer would have put some thought into integrating the two, perhaps largely or entirely turning over choices to the more judicious human forebrain (except possibly during time-limited emergencies, where we have to act without the benefit of reflection). Instead, our ancestral system seems to be the default option, our first recourse just about all the time, whether we need it or not. We eschew our deliberative system not just during a time crunch, but also when we are tired, distracted, or just plain lazy; using the deliberative system seems to require an act of will. Why? Perhaps it's simply because the older system came first, and — in systems built through the progressive overlay of technology — what comes first tends to remain intact. And no matter how shortsighted it is, our deliberative system (if it manages to get involved at all) inevitably winds up contaminated. Small wonder that future discounting is such a hard habit to shake.

Choice slips a final cog when it comes to the tension between logic and emotion. The temptation of the immediate present is but one example; many alcoholics know that continued drink will bring them to ruin, but the anticipated pleasure in a drink at a given moment is often enough to overwhelm sensible choice. Emotion one, logic