The Sunday New York Times has a great article — the first of a series on aging — titled “So Big and Healthy Nowadays That Grandpa Wouldn’t Even Know You.” Reporter Gina Kolata begins with this 19th-century biography:

Valentin Keller enlisted in an all-German unit of the Union Army in Hamilton, Ohio, in 1862. He was 26, a small, slender man, 5 feet 4 inches tall, who had just become a naturalized citizen. He listed his occupation as tailor.

A year later, Keller was honorably discharged, sick and broken. He had a lung ailment and was so crippled from arthritis in his hips that he could barely walk.

His pension record tells of his suffering. “His rheumatism is so that he is unable to walk without the aid of crutches and then only with great pain,” it says. His lungs and his joints never got better, and Keller never worked again.

He died at age 41 of “dropsy,” which probably meant that he had congestive heart failure, a condition not associated with his time in the Army. His 39-year-old wife, Otilia, died a month before him of what her death certificate said was “exhaustion.”

But his modern-day descendant, living in the same town of Hamilton, is healthy and going strong at 45. Kolata interviews doctors, economists, and gerontologists to find out why Americans are taller, heavier, healthier, and living longer. Describing the research of Nobel laureate Robert W. Fogel and his colleagues on Union Army veterans, she notes:

They discovered that almost everyone of the Civil War generation was plagued by life-sapping illnesses, suffering for decades. And these were not some unusual subset of American men — 65 percent of the male population ages 18 to 25 signed up to serve in the Union Army. “They presumably thought they were fit enough to serve,” Dr. Fogel said.…

People would work until they died or were so disabled that they could not continue, Dr. Fogel said. “In 1890, nearly everyone died on the job, and if they lived long enough not to die on the job, the average age of retirement was 85,” he said. Now the average age is 62.

Much of this research has surprised scholars:

Life expectancy, for example, has been a real surprise, says Eileen M. Crimmins, a professor of gerontology and demographic research at the University of Southern California. “When I came of age as a professional, 25 years ago, basically the idea was three score years and 10 is what you get,” Dr. Crimmins said. Life span was “this rock, and you can’t touch it.”

“But,” she added, “then we started noticing that in fact mortality is plummeting.”

So why? Why has this epochal change — what Fogel calls “a form of evolution that is unique not only to humankind, but unique among the 7,000 or so generations of humans who have ever inhabited the earth” — happened? Kolata discusses the benefits of better nutrition, cheaper food, vaccines, and antibiotics. But still:

“That’s the million-dollar question,” said David M. Cutler, a health economist at Harvard. “Maybe it’s the trillion-dollar question. And there is not a received answer that everybody agrees with.”

Kolata is a science reporter, so she’s looking for a scientific answer, and she’s found several that contribute to our health and longevity. But she’s missed the forest. What is it that started changing in the United States and northern Europe in the past few centuries? (Fogel’s book on the general trend is The Escape from Hunger and Premature Death, 1700–2100: Europe, America, and the Third World.) Technology, yes. Nutrition and antibiotics and a better understanding of diet and exercise, absolutely. But what caused those things to appear after, as Fogel says, 7,000 generations?

Capitalism.

The introduction of the institutions of economic freedom in the Netherlands, Great Britain, the United States, and then the rest of the world beginning around 1700 caused what historian Steven Davies calls a “wealth explosion.” A great part of the unprecedented wealth creation went into sanitation and more abundant food and later into the research necessary to produce vaccines and antibiotics. Those institutions include secure private property, the rule of law, open markets, and economic freedom generally — or what Adam Smith called “peace, easy taxes, and a tolerable administration of justice.”

Capitalism has made the West rich and thus healthier and longer-lived. It could do the same for Africa, Asia, and the Arab world.

Kolata overlooked this point. Her article never mentions capitalism, freedom, or even wealth as an answer to the trillion-dollar question. But it’s still a great report on just how much better off we are. For more data on such trends, check out It’s Getting Better All the Time: 100 Greatest Trends of the Last 100 Years by Stephen Moore and Julian L. Simon.