He was an old former military man. Past his prime, many said. He had run for president already — and he had lost badly.

Now, in 1840, William Henry Harrison was running again. At age 67, Harrison was a weather-beaten former general without any truly significant military victories to his credit. While his supporters called him “Old Tippecanoe,” his detractors labeled him “Old Granny.” One opposition newspaper wrote that Harrison was a “superannuated and pitiable dotard.”

Harrison was running against incumbent President Van Buren, a man 10 years his junior. Van Buren was one of the cleverest politicians of his time. During his tenure as Andrew Jackson’s secretary of state, he outmaneuvered Jackson’s vice president, Southern firebrand John C. Calhoun, eventually replacing Calhoun as vice president and earning himself the nickname “The Little Magician.”

To beat Van Buren, Harrison would have to demonstrate youth and vitality. He would have to show Americans that he could stand up to the pressures of office.

He would have to drink large amounts of hard cider.

During the 1840 campaign, one of Harrison’s political enemies stated that if Americans truly wanted to be done with Harrison, they ought to give him “a barrel of hard cider, and settle a pension of two thousand a year on him, and my word for it, he will sit the remainder of his days in his log cabin … .” Harrison’s advisors quickly seized on the rustic imagery of hard cider and log cabins, which contrasted favorably with Van Buren’s reputedly excessive urban tastes.

Log cabins and hard cider quickly became the symbols of the Harrison campaign. Harrison himself guzzled hard cider during his speeches in an attempt to demonstrate his virility.

It worked. Harrison won the presidency in a landslide. One month after his inauguration, he died of pneumonia.

One of the myths of modern politics is that younger presidential candidates have an inherent advantage. Americans want their presidents healthy — after all, the presidency is no cakewalk. But as long as candidates demonstrate youthful vitality, age is just a number. Ronald Reagan won the presidency at age 69 and again at age 73. Dwight Eisenhower was elected at 62 and reelected at 66. FDR won a third term at age 62, despite ubiquitous, and truthful, rumors of his declining health.

In fact, Americans may prefer older candidates as a whole. During the 19th century, candidates under age 50 lost seven of the 12 elections in which they ran; candidates under age 48 lost seven of nine times. Over the course of the century, the average president was elected at age 56.

Not much has changed since 1900. During the 20th century, candidates under age 50 lost six out of 10 times. The average age of elected presidents remained 56. The television era, surprisingly, increased the average age of victorious presidential candidates; since 1952, our presidents have been elected at the average age of 58.

All of which should make Senator McCain a happy man. He, like Harrison in 1840, is a nationally known military and political figure. Mr. McCain, like Harrison, ranks high on the age scale — he turns 72 in August, and has hinted that he will serve only one term even if he wins the presidency.

Most important, however, Mr. McCain, like Harrison, is a feisty fellow. He’s highly energetic and quite pugnacious. His biggest image flaw is his often over the top bellicosity, an attribute that suggests vigor rather than lassitude. If he can temper that bellicosity with the sort of genial, paternal feel of a Reagan or an Eisenhower, he will be a formidable candidate.

The flip side of the same coin is Senator Obama. He, like John F. Kennedy in 1960, is running on his youth. Mr. Obama will turn 47 in August. Unlike JFK, however, he is dramatically inexperienced in national politics — JFK had served in federal office for 14 years when he ran in 1960, as opposed to Mr. Obama’s four. The junior senator of Illinois has more in common with William Jennings Bryan circa 1896, age 36, than JFK: both are rhetorical spellbinders focused more on broad platitudes than hard policy.

The conventional wisdom says that Mr. McCain will look broken-down next to the vibrant Obama. History suggests otherwise. Americans like their politicians seasoned, as long as that seasoning isn’t linked to decrepitude. And John McCain certainly isn’t decrepit.

Mr. Shapiro, the author of “Project President: Bad Hair and Botox on the Road to the White House,” is a nationally syndicated columnist and a lawyer at Goodwin Procter LLP in Los Angeles.