I knew it!

You probably did too.

People generally are getting dumber. Not anyone reading or writing this post, of course. But the world population in general.

IQ levels inexorably rose during the last century, about three points per decade, according to established research. Now they’re not.

In fact, IQ levels are actually in decline — and not just in Congress.

According to a number of studies, beginning around the turn of this century, IQ test scores were found to be declining across Britain, Germany, Scandinavia, Australia and France. (But don’t tell the French. They won’t believe you anyway.)

IQ levels can be controversial, of course. Over time, for instance, they’ve provided cocktail party bragging rights for some parents.

But they’ve become accepted as generally predictive of things like individual achievement success in school. And for societies in general, collective IQs have been accurate indicators of innovation and economic growth.

Now comes a worried Evan Horowitz in an intriguing and provocative think piece:

If IQ scores are really dropping, that could not only mean 15 more seasons of the Kardashians, but also the potential end of progress on all these other fronts, ultimately leading to fewer scientific breakthroughs, stagnant economies and a general dimming of our collective future.

Initially, explanations centered on social factors such as the influx of less-educated immigrants and less-educated families producing more children.

That was debunked as evidence emerged that IQ levels were declining in native-born children. And, interestingly, IQ scores were also dropping even in children from high IQ parents.

No one knows for sure yet. But a suspected environmental cause or causes includes the growing dominance of lower-skilled jobs, which stimulate brains less, letting them get lazy and mentally flaccid from lack of exercise.

Also perhaps less nutritious foods not building healthy, nimble brains, or my favorite, the vast contemporary array of electronic devices weakening our mental abilities to focus. (If you’re reading this on your cell, stay focused. You’re almost done.)

Horowitz worries that the precise causes need to be determined soon before the IQ rot spreads to the United States and causes widespread economic stagnation, among other dire things.

And also before a “global intelligence crisis” saps human’s mental abilities to cope and manage new challenges like, oh, say, the rapidly-evolving IQ of artificial intelligence.