The Warren comments elicited applause, as you might expect, but it was Leno's next comments that raise an interesting point. "I ask people," he said, "'How much younger is Elizabeth Warren?' 'Oh, 15 years.' 'No! 18 months!'"
Certainly in part because Hillary Clinton has been on the national stage so long (some 23 years, if you're counting), people do tend to assume that she is significantly older than Sen. Warren (D-Mass.), who's only served in the Senate since 2013. In the possible Democratic field for 2016, however, the two of them are actually among the younger possible nominees, despite critiques from people like Sen. Rand Paul (R-Ky.).
The average age that the possible Democratic contenders would be at inauguration in 2017 is 68.6, just under the 69.3 years that Clinton would be. That's a full decade older than average inauguration age of the much-bigger, much-younger possible Republican field -- the oldest of whom is a gentleman named Mitt Romney. The Republicans average 57 years in age on January 20, 2017.
This doesn't really tell us much about what's likely to happen over the next 22 months, particularly when you consider the past few elections. On the day of the 2009 inauguration, Barack Obama was significantly younger than Sen. John McCain (R-Ariz.) -- as was Bill Clinton younger than George H. W. Bush when inaugurated in 1993. But George W. Bush was only slightly older than Al Gore in 2001, while Ronald Reagan was significantly older than Walter Mondale by the time his second inauguration rolled around in 1985.
Reagan, of course, offered one of the all-time great responses to questions of his age.
One can imagine Hillary Clinton leveling a similar line against Warren in a debate. "I will not make age an issue in this campaign. I will not exploit for political purposes my opponent's youth and inexperience."
A line like that could easily vault a person into the ranks of the 100 million funniest people in America.