Americans are living longer, healthier lives than ever before. Violent crime rates are approaching 30-year lows. Our culture

is infused with rich, up-to-date perspectives on news of all sorts, thanks largely to the rise of the Internet. Institutionalized racial discrimination continues a vanishing trend. Even the environment appears on the mend: Combined emissions of the six principal pollutants have fallen almost 50 percent since 1970.

Still, Americans are no happier for it. According to surveys, people are no more likely to score themselves “happy” today than they were two generations ago. Perhaps most telling, the rates of depression in the United States over the last several decades have followed a depressing course, increasing tenfold since the 1950s.

So go the thoughts of Gregg Easterbrook of The New Republic on his Web log, in his new book, “The Progress Paradox,” and in interviews given to the Public Broadcasting Service. So also go the thoughts of many of us, including myself.

Each day in the hospital I see patients and their discontents – discontent that the care they receive does not meet their expectations. “Can’t you do something about the pain?” Or “the nausea?” Or “Why can’t this be cured?” Despite mind-boggling advances in medical care – or maybe because of them – patients are increasingly less likely to rate themselves “healthy.” The paradox of health is a phenomenon widely remarked on in the health-care community since the 1980s.

One argument runs that these trends of dissatisfaction only highlight how superficial and ungrateful we can be, but instead I think they might reveal something deeper, precisely because they are so pervasive. By all measures – as a comedian inadvertently kicking his hat forward at each attempt to pick it up – our expectations evolve just ahead of society’s real progress. What is the force behind this? Why do we keep kicking our figurative hats?

In an influential paper in the journal Nature, investigators at Emory University in Atlanta studied economic sensibilities in capuchin monkeys (females were used in the experiment because they apparently more closely monitor fair treatment among their peers; sorry guys).

Monkeys were trained to exchange a rock for a reward, usually a cucumber slice. They were then paired with another capuchin. Partners were trained the same way but received an alternative, more highly valued reward: a grape (hey, they’re monkeys, not college students). Incredibly, monkeys getting the inferior reward often refused to carry out future exchanges and sometimes, in apparent defiance, actually threw their rewards back at the human researchers! A better reward seen just next door – a grape – had abruptly devalued the once perfectly adequate cucumber slice.

This is the animal world’s “Keeping up with the Joneses,” a comic strip about a couple who became obsessed with maintaining parity with their upstairs neighbors. The cartoon didn’t enter the U.S. cultural landscape until 1916, but the behavior illustrated by capuchin monkeys provides compelling evidence that, in principle, it was here all along.

Economists have long recognized “opportunity cost.” It is defined on Economist.com as the true cost of something, including what you had to give up to get it. For me, a medical student, the opportunity cost of my training is large. Not only is medical school tuition steep and getting steeper, but I’ve also given up early, prime money-making years to go to school. (Yes, the payoff in the end is substantial and I’m not complaining.)

Numerous studies have demonstrated opportunity cost in humans, and in doing so, have gone some distance in unearthing a link to the capuchins’ “Keeping up with the Joneses.” According to a recent article in The New Yorker, “The Paradox of Choice,” two Princeton psychologists, “asked experimental subjects how they would react to a desirable Sony appliance placed in a shop window, radically marked down. The offer met with predictable enthusiasm. When a second appliance, similarly marked down, was placed alongside the bargain Sony, enthusiasm – and sales – dropped.” In other words, a bargain doesn’t seem so fantastic in the company of other good deals because choosing one suddenly means giving up all the others – a relative increase in opportunity cost. Like capuchins, our standards of value are adjusted to context.

The paradoxes of progress, health and choice illustrate a common theme: We are never satisfied with the status quo because our expectations are continuously ratcheted a bit beyond. These paradoxes certainly contribute to disappointment, but they might also be responsible for the incredible innovation our society has seen. The force kicking the hat might just be our paradoxical discontent, and it is society’s advance that runs to catch up.

Abram Burgher is a University medical student. He welcomes comments at [email protected]