Politicians have a long history of swearing. Surreptitious recordings of the White House during the Johnson and Nixon administrations in the 1960s and ’70s document extensive presidential profanity.

Andrew Jackson reportedly swore so much that his pet parrot started imitating him, to the point that it had to be removed from Jackson’s funeral. But for the most part, politician profanity has been either fleeting or shuttered behind closed doors — until recently.

Over the last several years, we’ve seen a substantial uptick in public political profanity. As a candidate, Donald Trump’s early stump speeches were often punctuated by swear words — words that require some creativity to write about in a family newspaper.

In a speech in New Hampshire in early 2016, Trump used a coarse term for a female body part to refer to a fellow Republican candidate for president, Ted Cruz. (Trump had previously been recorded using the same word while talking about grabbing women.) Trump the candidate also was comparatively loose with weaker profanity like “hell” and made scatological references.

Cut to the current presidential campaign, where about half of the Democratic candidates have gone on the record swearing. It’s gotten to the point where the Democratic National Committee and ABC News reportedly instructed candidates to avoid swearing before Thursday’s debate.

Avoiding profanity will be more challenging for certain candidates. Beto O’Rourke seems almost to have made prolific use of the F-word one of the planks of his platform.

Asked about a mass shooting in Texas, he responded: “This is fouled up,” except he didn’t say “fouled.” (Family newspaper, remember.)

And he’s now selling campaign T-shirts branded with the profane version of that phrase. Cory Booker also seems quite comfortable swearing on the record, as did Kirsten Gillibrand, who dropped out of the race last month.

This trend is more than just anecdotal. Research by analytics firm GovPredict found that politicians’ use of profanity on Twitter has taken off. In the three years ending in 2016, politicians tweeted a total of 408 profanities. Contrast that with the next three years, when profane tweets increased by nearly 15 times, to 6,047.

2016 was clearly a turning point for how politicians use language.

You might imagine that this increase has been due to the intensity of emotions stirred by the current political moment. After all, we know that profanity increases when people are angry, fearful, excited or otherwise emotionally aroused.

But it’s far more likely that the swearing is strategic.

Presidential candidates finely craft their public images. Given the consideration they give to every word in every message, it seems unlikely that even profound emotional arousal would cause their tongues to slip.

Further evidence comes from who uses the bulk of the profanity.

Consider the 20 candidates still in the running for the Democratic nomination for president. The front-runners aren’t swearing. Or if they are, it’s very mild, like Bernie Sanders’ “I wrote the damn bill” refrain, which was bandied about in Thursday’s debate.

Or Elizabeth Warren’s purported favorite swear word: “poop.” Both words can be printed in this family newspaper, providing further evidence that the front-runners are using uncontroversial language.

Meanwhile, the underdogs are loosing their tongues. O’Rourke and Booker — whose examples of profanity couldn’t be quoted in these pages — are polling under 5 percent. A radical and risky change in behavior like this in the underdogs alone screams strategy. Author Malcolm Gladwell might call this a “David strategy,” a chancy approach that a desperately overpowered David would resort to, but that a front-running Goliath would never need to risk.

Here’s how the strategic thinking might go. Swearing serves as a social signal. Listeners judge people who swear to be more honest and more intense. It’s clear why a candidate might want to be seen this way.

However, people may also judge swearers to be untrustworthy, incompetent and vulgar. In using swearing as a strategy, the calculus is that the positive effects may outweigh the negative ones.

Adopters of this strategy might be hoping that their target audience responds favorably to profanity. It’s known that the younger and less religious among us view profanity more favorably. Politicians competing for younger and less religious voters (who are disproportionately represented among Democrats) might see more of an upside.

Under these conditions, swearing might move the needle. But not much, and it’s not clear in which direction. Too many other things are working against it.

First, the negative effects are real. Attracting younger, less religious voters through profanity risks the potential cost of alienating older, more religious voters, or any voter who happens to object to profanity.

In addition, younger people’s attitudes toward profanity have changed over the years, to the point where the type of profanity politicians use may not have much impact on them.

Profanity has erupted in the public sphere on cable television, streaming video, social media and in online gaming.

As a consequence, most of comedian George Carlin’s “seven dirty words” that you can’t say on TV are often judged to be only marginally offensive by people under the age of 40. So the target voting population may be underwhelmed by swearing they view as tepid.

And finally, if members of the electorate believe that politicians are swearing strategically, it might backfire. Younger voters might find the swearing inauthentic or cynical — as a painful but failed attempt to act hip.

To win our votes, politicians need to grab our attention. Using profanity definitely does that. When four-letter words are unexpected, they can be quite memorable. Hearing them increases the listener’s heart rate and releases adrenaline. But profanity is no panacea. And media analysis that calls this strategic swearing out for what it is (as I’m doing here) certainly won’t make it any more effective.

Benjamin Bergen is a professor of cognitive science at UC San Diego and author of “What the F: What Swearing Reveals About Our Language, Our Brains, and Ourselves.”