Lately the process has been a little more frenetic. Over the past few centuries, and accelerating ever more quickly in the past 50 years, a steady stream of human innovations has begun to drastically speed up processes that were, until very recently, the sole province of nature. In short, it appears that our technology has created ways of accelerating change (genetic engineering, for instance) and new habitats (like the modern city), essentially fracturing our biology and transforming our future as a species.
The first inkling that something might be wonky with gradualism—as Darwin’s slow process of evolutionary change is known—did not emerge from biology. It showed up in economics, specifically in an economic analysis of slavery in America.
Most slaves, especially those on smaller plantations, were fed better and lived in better conditions than freemen in the North.
In 1958, Harvard economists Alfred Conrad and John Meyer published a book
arguing that slavery may have been immoral but still made economic sense—which was too much for a University of Chicago economist named Robert Fogel to abide. Fogel was white, but his wife was African American. Very African American. “When I was teaching at Harvard,” Fogel recounts, “she hung a sign outside the door to our house. It read: “Don’t be upset because you’re not black like me—we’re not all born lucky.”
Fogel decided to prove Conrad and Meyer wrong. He spent almost a decade on the problem. In his earlier work, Fogel had helped pioneer the application of rigorous statistical analysis and other economics-based mathematical methods to the study of history (research that earned him a Nobel Prize in 1993).
Now, working alongside University of Rochester economist Stanley Engerman, Fogel began applying these methods to the study of slavery. This enterprise led him deep into the relationship between economics, physiology, and longevity, where he analyzed variables such as the amount of food consumed by the average slave (or freeman) measured against the amount of work he produced.
To make such comparisons, Fogel needed data and metrics. For data he used a National Institutes of Health–funded database of American Civil War veteran records: an informational treasure trove containing details like height and weight at time of conscription, daily roll calls of the sick and injured, periodic postwar checkups, census data, and, often, death certificates.
For metrics he chose height and body mass, because of a steadily growing consensus among scientists that these factors were accurate predictors of mortality and morbidity. “Height,” says UCLA economist Dora Costa, who cowrote papers on these ideas with Fogel, “turns out to be a fantastic health indicator. It’s net for nutrition, infectious disease, sanitation, and demands placed on the body.” (The United Nations now uses height as a way to monitor quality of nutrition in developing countries.)
What all this information provided was a population-eye view of life in the 19th century, which is exactly what Fogel needed in order to understand broad socioeconomic trends and reach startling conclusions. The first of those conclusions, which he and Engerman detailed in 1974 in their now-famous Time on the Cross: An Economic Analysis of American Negro Slavery, was that Conrad and Meyer were correct after all: Slavery, while repugnant, was neither as inefficient nor as unprofitable as most historians assumed.
“As it turns out,” Fogel recounts, “most slaves, especially those on smaller plantations, were fed better and lived in better conditions than freemen in the North. This meant they lived longer, healthier lives and thus produced more work. Certainly, it’s an odious conclusion, but it’s right there in the data.”
Then around 1988 Fogel began to notice a startling trend in the data: Over the past few centuries, but predominantly in the 20th century, Americans have been growing taller. They have also been getting thicker, living longer, and getting richer.
In 1850, for example, the average American male stood 5 feet 7 inches and weighed 146 pounds. By 1980 those numbers had jumped to 5 feet 10 and 174 pounds. And it was not just Americans. A team of economists expanded this inquiry internationally, and discovered that the trends were global.
“Over the past 300 years,” Fogel says, “humans have increased their average body size by over 50 percent, average longevity by more than 100 percent, and greatly improved the robustness and capacity of vital organ systems.”