My father-in-law was something of a cut-up. When he finished high school during the early 1920’s, he wasn’t the star scholar of his class, but he was good at telling a story. His classmates demanded that he be chosen to give the graduation address.
From a few pictures of the time, I can see in my mind’s eye his slicked back hair with the cowlick that refused to lie down, the somewhat unevenly polished shoes his mother had persuaded him to wear with his best suit. His title was “The Iron Bedstead Menace.”
He never shared the text of his remarks with us, but I can also picture his well-timed delivery, alternately amusing and frightening his audience. He had learned from a magazine article somewhere that the prevalence of iron bedsteads was widespread and continued to grow.
Grandpa Batterson presented ample evidence of the rapid ascendancy of iron bedstead production and ownership. He projected the continuing growth of the trend, until the Chicago suburb where he and his family lived would be overwhelmed with bedsteads everywhere. These bulky, never-decaying items would over time leave little room for other furniture; discards would fill area dumps and backyards to overflowing. People should beware and take action to ban this creeping menace, before it was too late, he concluded.
Per a contemporary article on a Home/Office/Garden website: “Owning an iron bed became a status symbol in the late 19th and early 20th centuries. As they were more expensive than the basic wooden beds, having an ornately designed iron bed indicated a family’s wealth and modernity. The intricate designs also reflected the artistic tastes and sophistication of the household. (https://hogfurniture.co/blogs/ideas-inspiration/the-importance-of-antique-iron-beds-historically-and-currently, accessed 11/22/2025)” (In hindsight, we’ve learned that the incidence of such beds actually declined as the 1920’s progressed, their overly ornate designs supplanted by more modest furniture.)
The Roslings use global human population growth as evidence of the straight line fallacy—over the centuries, pundits have repeatedly suggested that human population will continue to increase until limited by our finite planet. In its most recent incarnation, the expectation that population will continue its recent upward trajectory fooled lots of sustainability experts at conferences Rosling attended. As Rosling explains: “The number of future children is the most essential number for making global population forecasts. … The numbers [of children globally] are freely available online, from the U.N. website, but free access to data doesn’t turn into knowledge without effort. … U.N. experts expect that in the year 2100 there will be 2 billion children, the same number as today. … [Because] (a)fter 1965 the number [of babies per woman globally] started dropping like it never had done before. Over the last 50 years it dropped all the way to the amazingly low average of just below 2.5.”
It’s natural for us to expect a certain stability in rates of change of a given phenomenon, but, as the Roslings point out, such stability is not universal. Straight line increases are no more common than s-bends, slides, bumps, or doubling lines. We need to pay attention to the assumptions we are making about the shape of a line or curve, and adjust our expectations as conditions change.
(Last time I checked, the Chicago area was not drowning in iron bedsteads.)
Jinny's Occasional Poems 