In A Nutshell
A Belgian statistician invented the BMI scale in 1832, and he didn’t stop there. A proponent of “social physics,” Adolphe Quetelet believed that everything could be measured and compared, and that statistics was the key to unlocking the mysteries of social phenomenon. He spent years trying to develop scales for measuring things like morality and courage.
The Whole Bushel
When it comes to health and nutrition, one of the most well-known scales might be the body mass index scale, or BMI. It’s a pretty simple concept invented by a 19th-century Belgian mathematician when he claimed to discover that after puberty, a person’s ideal weight is their height squared.
For some reason, the idea that it’s an accurate way to measure obesity stuck, in spite of the fact that it ignores some pretty big factors like waist size, muscle density, and bone density. At the end of the day, that means that a lot of people who are in incredibly good shape—like most professional athletes—will be considered obese by the scale.
The scale has a fascinating history, though, and it all revolves around its inventor. Adolphe Quetelet was born in 1796, and he first published what he called the Quetelet Index in 1832. (Ancel Keys gave it the modern name in 1972.)
Quetelet was a huge fan of statistics. In 1853, he organized the International Statistical Congress and tried to categorize the causes of death around the world.
When he turned his attention to measuring obesity on a scale, he was breaking new ground. The idea that being overweight was a bad thing was still new.
For generations, carrying some extra pounds was a sign that you were healthy, wealthy, and enjoying the good life. Negative health impacts were only being explored in the mid-1800s. (Before that, the only worry was that being too heavy could have a negative impact on your enjoyment of life.)
Quetelet found that it was pretty straightforward, once a person got past the turbulent time that is puberty. The healthiest weight, he determined, was measured in kilograms and was the square of the person’s height, measured in meters. (Today, we know that’s not the case.)
But that’s not the only thing Quetelet tried to quantify in a neat little table.
He was working in a field that he called “social physics.” Just like he believed a person’s height and weight followed the same sort of bell curve that they had already seen in other sciences, he thought there should be a similar way to measure things like intelligence, morality, and courage.
Much like he had collected huge amounts of data to plug into his bell curve and determine an average and acceptable height and weight, he considered factors like an area’s criminal activity. For example, he might try to determine the average criminal propensity a person from Brussels might have.
His studies in morality were even more far-fetched. His problems there started with how to even quantify morality. Height was measured in meters and weight in kilograms, but what units could morality be measured in?
And there was an even bigger problem. Someone might be the most courageous person in the world, but unless something happened to give him the chance to prove his courage (and unless someone was there to see and record it), it didn’t matter.
Quetelet shared his idea with others, who promptly called him a bit of a nutter. Forced to defend the whole concept, Quetelet stated that he was simply laying the groundwork for scales that would be developed later, likening his work to astronomy. That had been considered an insane science once, and all it had needed to gain credibility was some work and some concrete theories.
Of course, he was a little bit right. We have scales to measure intelligence now, but scales for courage remain a bit more elusive.
Quetelet continued to argue that all that was needed was a way to gather data, and that his scales, measurements, and comparisons were not absurd at all—just elusive.
Show Me The Proof
Nephrology Dialysis Transplantation: Adolphe Quetelet—the average man and indices of obesity
NPR: Top 10 Reasons Why The BMI Is Bogus
Adolphe Quetelet, Social Physics and the Average Men of Science, 1796–1874, by Kevin Donnelly
