If the 22nd Amendment didn't exist and 73-year-old Bill Clinton had improbably joined the Democratic primaries before the Nevada caucuses, he would have been the second youngest man on the Feb. 19 debate stage after 38-year-old Pete Buttigieg, a viral tweet recently informed us. (This was before 62-year-old Tom Steyer qualified for the South Carolina debate.) Hammering the point home, 77-year-old former Vice President Joe Biden observed afterwards that he was the second youngest man on stage in Las Vegas.

All of which is to say that the Democratic finalists are really old by historical standards. The frontrunner, in fact, is the oldest: 78-year-old Sen. Bernie Sanders, who suffered a heart attack on the campaign trail. And the winner of the primary will face Donald Trump, already the oldest man ever sworn into a first term as president. While supporters of each candidate dismiss questions about their fitness and age as ageism or applicable to others but not their chosen candidate, the parade of older candidates is bad for our politics.

Times have certainly changed. In 1980, the 69-year-old Ronald Reagan became the oldest president ever elected. Reagan's age was an issue — he pledged to resign if there were signs that his "capabilities had been reduced." Fueling questions was the reality that the average life expectancy for a 65-year-old white male at the time was 14.2 years.

The age question resurfaced after Reagan uncorked a woeful performance in his first face-off against former Vice President Walter Mondale in 1984. Reagan famously defused doubts with a zinger in their second debate, pledging "I will not make age an issue of this campaign. I am not going to exploit, for political purposes, my opponent's youth and inexperience."

Nonetheless, some believe that Reagan was cognitively less sharp and engaged in his second term, although claims that he already had Alzheimer's symptoms have never been proven.

Between 1988 and 2016, Republicans ran two candidates over 70 — the 73-year-old Bob Dole and the 72-year-old John McCain — and Democrats none. There were questions about Dole's age and fitness, exacerbated when he fell at a campaign rally. Roughly a third of poll respondents believed that Dole was too old or that his age was an "obstacle to being an effective president;" he even fielded a debate question about it.

Twelve years later, McCain calmed fears about his age by publicly releasing almost 1,200 pages of medical records. But both Dole and McCain lost to far younger nominees.

Yet, whatever barrier advanced age once posed to getting elected president has evaporated over the last four years. Trump's age may not have posed an obstacle in 2016 because his opponent, Hillary Clinton had herself turned 69 on the eve of the election (and she was the younger of the two major Democratic contenders). But this year, with a Democratic field full of accomplished younger officeholders, four of the seven legitimate remaining contenders are 70 or older: the 70-year-old Sen. Elizabeth Warren, Biden, Sanders, and 78-year-old former New York Mayor Michael Bloomberg.

In fairness to the candidates, life expectancy has risen since Reagan's presidency, reaching 18.1 years for 65 year old men and 20.7 for women — meaning an average lifespan would carry all of the contenders through a first term, albeit just barely for Sanders. But that doesn't guarantee fitness to do a grueling job that seems to age all of its occupants. And there are downsides to older candidates outside of questions about their capacity.

First, their familiarity from years in the spotlight and connections forged from decades of cultivating activists and donors give older candidates significant built-in advantages. That means they draw a lion share of attention from the media, which focuses on a relatively narrow band of candidates at any given moment. This makes it hard for younger contenders to gain attention.

As Democratic strategist James Carville recently noted, Biden occupied the oxygen and attention in the "mainstream" lane of the primary, making it impossible for candidates like Sens. Cory Booker and Michael Bennet, and Montana Gov. Steve Bullock to gain traction and raise money. This reality kept voters from ever really getting exposed to unique candidates with fresh ideas and perspectives. As veteran reporter Andrea Mitchell lamented about Bennet's candidacy, "This was one of the most thoughtful candidates to run for president — and not get an adequate hearing. Maybe next time."

Second, the long records of older candidates have become fodder in the campaign — frequently judged by 2020 standards with little regard for historical context. Instead of leading to fruitful debates on candidates' visions or their plans to deliver, Biden's decades-old record on school busing or Sanders' 1980s comments on authoritarian socialist regimes have stolen headlines. At a moment when our focus needs to be on the future, long records keep it trapped on the past.

Finally, our world is changing at dramatic speeds. Even people in their 30s and 40s can find technological innovations (especially proliferating social media platforms) disorienting. Technology and changes in cultural norms have dramatically remade every realm of American life and the demands facing everyone from professionals to young families to workers losing jobs (or who will lose jobs) to automation — something raised during the primary by 45-year-old Andrew Yang. How many people under 50 have struggled to explain to elders why the demands of their jobs are more relentless because of the rise of smart phones, which keep them tethered to work 24/7? Or why their generations move from job to job more far more frequently? Let alone millennials' preference for text messaging over phone calls or even email, the rise of meal services, how to guard against phishing schemes, or there being more than two genders.

Fundamentally, younger candidates have a better grasp of the needs of millennials (and generations X and Z) because they've more fully inhabited this new, ever changing world. This enables them to offer more creative solutions — with a better shot of bridging ideological divides — to many of our problems.

Which is not to say that older Americans don't have good ideas, or can't contribute to our politics. Experience is valuable; one can argue that Buttigieg, for example, could've used more seasoning before running for president. But when you add all of these factors together, we'd be better off if candidates in their upper 70s stepped aside and let younger generations of leaders, better suited to the intense demands of the presidency, pick up the baton.

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