Nor is the car-seat solution as simple as most people might like. Any given seat is a tangle of straps, tethers, and harnesses, built by one of dozens of manufacturers, and it must be anch.o.r.ed in place by a car's existing seat belt-whose configuration varies depending on its manufacturer, as does the shape and contour of the rear seat itself. Furthermore, those seat belts were designed to batten down a large human being, not a small, inanimate hunk of plastic. According to the National Highway Traffic Safety Administration (NHTSA), more than 80 percent of car seats are improperly installed. That's why so many parents trek to the local police station or firehouse for help with the seats. And that's why NHTSA runs a four-day National Standardized Child Pa.s.senger Safety Training Program for public-safety personnel, using a 345-page manual to teach proper installation.

But who cares if car seats aren't so simple or cheap? Not every solution can be as elegant as we might like. Isn't it worth a police officer sacrificing four days of work to master such a valuable safety device? What matters is that car seats are effective, that they save children's lives. And according to NHTSA, they do, reducing the risk of fatality by a whopping 54 percent for children ages one to four.

Curious parents may have a question: a 54 percent reduction compared with what?

That answer can easily be found on NHTSA's own website. The agency maintains a trove of government data called the Fatality a.n.a.lysis Reporting System (FARS), a compilation of police reports from all fatal crashes in the United States since 1975. It records every imaginable variable-the type and number of vehicles involved, their speed, time of day, where the pa.s.sengers were sitting in the car-including what kind of safety restraints, if any, were being worn.

It turns out that a child in a car seat is 54 percent less likely to die than a child riding completely unrestrained-that is, with no car seat, no seat belt, no nothing. That makes sense. A car crash is a violent affair, and a lot of terrible things can happen to a ma.s.s of flesh and bone when it is traveling fast inside a heavy metal object that suddenly stops moving.

But how much better is the complicated and costly new solution (the car seat) than the cheap and simple old solution (the seat belt), even though the simple solution wasn't meant for kids?

Seat belts plainly won't do for children under two years old. They are simply too small, and a car seat is the best practical way to secure them. But what about older children? Laws vary by state, but in many cases car seats are mandatory until a child is six or seven years old. How much do those kids benefit from car seats?

A quick look at the raw FARS data from nearly thirty years of crashes reveals a surprising result. For children two and older, the rate of death in crashes involving at least one fatality is almost identical for those riding in car seats and those wearing seat belts:

It may be that these raw data are misleading. Perhaps kids who ride in car seats are in more violent crashes. Or maybe their parents drive more at night, or on more dangerous roads, or in less-safe vehicles?

But even the most rigorous econometric a.n.a.lysis of the FARS data yields the same results. In recent crashes and old ones, in vehicles large and small, in single-car crashes and pileups, there is no evidence that car seats are better than seat belts in saving the lives of children two and older. In certain kinds of crashes-rear-enders, for instance-car seats actually perform slightly worse.

So maybe the problem is, as NHTSA admits, that too many car seats are installed improperly. (You might argue that a forty-year-old safety device that only 20 percent of its users can install correctly may not be a great safety device to begin with; compared with car seats, the condoms worn by Indian men seem practically infallible.) Could it be that the car seat is a miracle device but that we just haven't learned to use it properly?

To answer this, we sought out crash-test data for a side-by-side comparison of seat belts and car seats. You wouldn't think this would be hard to find. After all, every car seat brought to the market must undergo crash testing to gain federal approval. But it appears that researchers have rarely, if ever, run parallel tests on child-sized crash-test dummies. So we decided to do it ourselves.

The idea was simple: we would commission two crash tests, one with a three-year-old-sized dummy in a car seat versus a three-year-old dummy in a lap-and-shoulder belt, the other with a six-year-old-sized dummy in a booster seat versus a six-year-old dummy in a lap-and-shoulder belt. In each case, the test would simulate a thirty-mile-per-hour frontal collision.

We had a hard time finding a crash-test lab that would do our tests, even though we were willing to pay the $3,000 fee. (Hey, science doesn't come cheap.) After being turned down by what felt like every facility in America, we finally found one willing to take our money. Its director told us we couldn't name the lab, however, out of concern he might lose work from the car-seat manufacturers that were the core of his business. But, he said, he was "a fan of science," and he too wanted to know how things would turn out.

After flying in to this undisclosable location, we bought some new car seats at a Toys "R" Us and drove to the lab. But once the engineer on duty heard the particulars of our test, he refused to partic.i.p.ate. It was an idiotic experiment, he said: of course the car seats would perform better-and besides, if we put one of his expensive dummies in a lap-and-shoulder belt, the impact would probably rip it to pieces.

It seemed odd to worry over the health of a crash-test dummy-aren't they made to be crashed?-but once we agreed to reimburse the lab if the seat-belted dummy was damaged, the engineer got to work, grumbling under his breath.

The lab conditions guaranteed that the car seats would perform optimally. They were strapped to old-fashioned bench-style rear seats, which give a flush fit, by an experienced crash-test engineer who was presumably far better at securing a car seat than the average parent.

The ch.o.r.e was gruesome, from start to finish. Each child dummy, dressed in shorts, T-shirt, and sneakers, had a skein of wires snaking out of its body to measure head and chest damage.

First came the pair of three-year-olds, one in a car seat and the other in a lap-and-shoulder belt. The pneumatic sled was fired with a frightening bang. In real time, you couldn't see much (except that, to our relief, the seat-belted dummy remained in one piece). But watching the super-slow-motion video replay, you saw each dummy's head, legs, and arms jerk forward, fingers flailing in the air, before the head snapped back. The six-year-old dummies were next.

Within minutes, we had our results: the adult seat belts pa.s.sed the crash test with flying colors. Based on the head-and chest-impact data, neither the children in the safety seats nor those in the seat belts would likely have been injured in this crash.

So how well did the old-fashioned seat belts work?

They exceeded every requirement for how a child safety seat should perform. Think of it this way: if we submitted our data from the seat-belted dummies to the federal government and said it came from the latest and greatest car seat, our "new" product-which is pretty much the same nylon strap Robert McNamara pushed for back in the 1950s-would easily win approval. Since a plain old seat belt can meet the government's safety standard for car seats, perhaps it's not very surprising that car-seat manufacturers turn out a product that can't beat the seat belt. Sad, perhaps, but not surprising.

As one can imagine, our lack of appreciation for car seats places us in a slim minority. (If we didn't have six young children between us, we might well be labeled child haters.) One compelling argument against our thesis is called "seat-belt syndrome." A group of prominent child-safety researchers, warning that crash-test dummies typically don't have sensors to measure neck and abdomen injuries, tell grisly emergency-room tales of the damage seat belts inflict upon children. These researchers gathered data by interviewing parents whose children were in car accidents, and concluded that booster seats reduce significant injury by roughly 60 percent relative to seat belts.

These researchers, many of whom actively care for injured children, are surely well-meaning. But are they right?

There are a variety of reasons why interviewing parents is not the ideal way to get reliable data. Parents may have been traumatized by the crash and will perhaps misremember details. There's also the question of whether the parents-whose names the researchers harvested from an insurance company's database-are being truthful. If your child was riding unrestrained in a car crash, you might feel strong social pressure (or, if you think the insurance company will raise your rates, financial pressure) to say your child was restrained. The police report will show whether or not the vehicle had a car seat, so you can't readily lie about that. But every backseat has a seat belt, so even if your child wasn't wearing one, you could say he was, and it would be difficult for anyone to prove otherwise.

Are there data sources other than parent interviews that could help us answer this important question about child injuries?

The FARS data set won't work because it covers only fatal accidents. We did, however, locate three other data sets that contain information on all crashes. One was a nationally representative database and two were from individual states, New Jersey and Wisconsin. Together, they cover more than 9 million crashes. The Wisconsin data set was particularly useful because it linked each crash to hospital-discharge data, allowing us to better measure the extent of the injuries.

What does an a.n.a.lysis of these data reveal?

For preventing serious injury, lap-and-shoulder belts once again performed as well as child safety seats for children aged two through six. But for more minor injuries, car seats did a better job, reducing the likelihood of injury by roughly 25 percent compared with seat belts.

So don't go throwing out your car seats just yet. (That would be illegal in all fifty states.) Children are such valuable cargo that even the relatively small benefit car seats seem to provide in preventing minor injuries may make them a worthwhile investment. There's another benefit that's hard to put a price tag on: a parent's peace of mind.

Or, looking at it another way, maybe that's the greatest cost of car seats. They give parents a misplaced sense of security, a belief they've done everything possible to protect their children. This complacency keeps us from striving for a better solution, one that may well be simpler and cheaper, and would save even more lives.

Imagine you were charged with starting from scratch to ensure the safety of all children who travel in cars. Do you really think the best solution is to begin with a device optimized for adults and use it to strap down some second, child-sized contraption? Would you really stipulate that this contraption be made by dozens of different manufacturers, and yet had to work in all vehicles even though each vehicle's seat has its own design?

So here's a radical thought: considering that half of all pa.s.sengers who ride in the backseat of cars are children, what if seat belts were designed to fit them in the first place? Wouldn't it make more sense to take a proven solution-one that happens to be cheap and simple-and adapt it, whether through adjustable belts or fold-down seat inserts (which do exist, though not widely)-rather than relying on a costly, c.u.mbersome solution that doesn't work very well?

But things seem to be moving in the opposite direction. Instead of pushing for a better solution to child auto safety, state governments across the United States have been raising the age when kids can graduate from car seats. The European Union has gone even further, requiring most children to stay in booster seats until they are twelve.

Alas, governments aren't exactly famous for cheap or simple solutions; they tend to prefer the costly-and-c.u.mbersome route. Note that none of the earlier examples in this chapter were the brainchild of a government official. Even the polio vaccine was primarily developed by a private group, the National Foundation for Infant Paralysis. President Roosevelt personally provided the seed money-it's interesting that even a sitting president chose the private sector for such a task-and the foundation then raised money and conducted the drug trials.

Nor was it the government that put seat belts in cars. Robert McNamara thought they would give Ford a compet.i.tive advantage. He was dead wrong. Ford had a hard time marketing the seat belt, since it seemed to remind customers that driving was inherently unsafe. This led Henry Ford II to complain to a reporter: "McNamara is selling safety but Chevrolet is selling cars."

Some problems, meanwhile, seem beyond the reach of any solution, simple or otherwise. Think of the devastation Mother Nature regularly dishes out. By comparison, traffic fatalities seem eminently manageable.

Since 1900 more than 1.3 million people worldwide have been killed by hurricanes (or, as they are called in some places, typhoons or tropical cyclones). In the United States, the carnage has been lighter-roughly 20,000 deaths-but the financial losses have been steep, averaging more than $10 billion per year. In the s.p.a.ce of just two recent years, 2004 and 2005, six hurricanes, including the killer Katrina, did a combined $153 billion in damages to the southeastern United States.

Why so much damage of late? More people have been moving to hurricane-p.r.o.ne areas (it's nice to live near the ocean, after all), and a lot of them built expensive vacation properties (which drive up the property-damage totals). The irony is that many of these homeowners were lured to the ocean because of the scarcity of hurricanes in recent decades-and, perhaps, by the correspondingly low insurance rates.

From the mid-1960s until the mid-1990s, hurricane activity was depressed by the Atlantic Multidecadal Oscillation, a long-recurring climate cycle of sixty to eighty years during which the Atlantic Ocean gradually cools and then warms up again. The temperature change isn't drastic, just a couple of degrees. But it's enough to discourage hurricanes during the cool years and, as we've seen recently, empower them during the warm.

In some regards, hurricanes wouldn't seem to be such a hard problem to solve. Unlike other problems-cancer, for instance-their cause is well established, their location is predictable, and even their timing is known. Atlantic hurricanes generally strike between August 15 and November 15. They travel westward through "Hurricane Alley," a horizontal stretch of ocean running from the west coast of Africa through the Caribbean and into the southeastern United States. And they are essentially heat engines, ma.s.sive storms created when the topmost layer of ocean water edges above a certain temperature (80 degrees Fahrenheit, or 26.7 degrees Celsius). That's why they start forming only toward summer's end, after the sun has had a few months to warm up the ocean.

And yet for all their predictability, hurricanes represent a battle that humans seem to have lost. By the time a hurricane forms, there's really no way to fight it. All you can do is run away.

But outside of Seattle lives an intellectually venturesome fellow named Nathan who believes, along with some friends, that they've got a good hurricane solution. Nathan has a physics background, which is key, because that means he understands the thermal properties that define a hurricane. A hurricane isn't just a dynamo; it's a dynamo that comes without an "off" switch. Once it's begun ama.s.sing energy it cannot be shut down, and it's far too powerful to be blown back out to sea with a big fan.

That's why Nathan and his friends-most of whom are, like him, science geeks of some sort-want to dissipate the thermal energy before it has a chance to acc.u.mulate. In other words: prevent the water in Hurricane Alley from getting warm enough to form a destructive hurricane in the first place. Armies sometimes engage in a "scorched earth" policy, destroying anything that might be of value to the enemy. Nathan and his friends want to practice a "chilled ocean" policy to keep the enemy from destroying anything of value.

But, one might be tempted to ask, doesn't this const.i.tute playing with Mother Nature?

"Of course it's playing with Mother Nature!" Nathan cackles. "You say that like it's a bad thing!"

Indeed, if we hadn't played with Mother Nature by using ammonium nitrate to raise our crop yields, many readers of this book probably wouldn't exist today. (Or they would at least be too busy to read, spending all day scrounging for roots and berries.) Stopping polio was also a form of playing with Mother Nature. As are the levees we use to control hurricane flooding-even if, as in Hurricane Katrina, they sometimes fail.

The anti-hurricane solution Nathan proposes is so simple that a Boy Scout might have dreamt it up (a very clever one, at least). It can be built with materials bought at a Home Depot, or maybe even filched from the dump.

"The trick is to modify the surface temperature of the water," Nathan says. "Now the interesting thing is that the surface layer of warm water is very thin, often less than 100 feet. And right beneath it is a bulk of very cold water. If you're skin-diving in many of these areas, you can feel the huge difference."