An academic, a bald guy and a barber traveling together stop to make camp for the night. They arrange to each take a watch while the other two sleep, with the barber on first watch and the academic to follow. The barber gets bored as the bald guy and the egghead sleep, so he shaves the academic's head to pass the time. At the end of his watch, the barber wakes up the academic, who rubs his now hairless head and says, “This barber is an idiot—he woke up the bald guy instead of me.”

That joke is so old that when it was first told the Dead Sea just had a bad cough. It's one of some 265 in a quip collection called Philogelos, which translates to “Laughter Lover,” often cited as being the world's oldest book of jokes. If the story did not compel you to guffaw, no worries—when Samuel Johnson published parts of Philogelos, he said that the punch line left him befuddled.

Patient says to his doctor, “Every morning when I wake up I feel dizzy for a half hour.” Doctor says, “Get up a half hour later.”

That Henny Youngmanesque offering is also in Philogelos, which is the subject of intense scrutiny in the much newer book Laughter in Ancient Rome: On Joking, Tickling, and Cracking Up, by University of Cambridge classics professor Mary Beard. She points out that although Philogelos is thought to date back to the fourth or fifth century a.d., our copy “never existed in the ancient world, certainly not in the form in which we now read it.” What we have, as is true for much literature from antiquity, is an amalgam of surviving bits of various versions. Think of a giant game of telephone played in numerous languages for a couple of millennia.

A guy from the nitwit town of Kyme was swimming when it began to rain, so he dived down to keep from getting wet.

I have taken the liberty to rework these jokes the way I might tell them, which may actually be in the spirit of the Philogelos—in addition to being the kind of tract that a Roman might peruse in the barbershop, the collection may have been what musicians call a “fake book,” a compilation of simple versions of material that the performer then embellishes with his or her personal style.

A guy from the numbskull village of Abdera sees a eunuch talking to a woman and asks another guy if she's the eunuch's wife. The second guy says, “Eunuchs don't have wives.” And the first guy says, “Must be his daughter.”

Beard discusses theories of humor, power relationships, evolutionary psychology and much more in Laughter in Ancient Rome. But her focus is on the laughter itself. “One big question that hovers over the whole of the book,” she writes, “is this: How comprehensible, in any terms, can Roman laughter now be?”

An academic bumps into one of a set of identical twins on the street and says, “Was it you who died or your brother?”

Indeed, we may laugh today at the jokes that lampoon the absent-minded professor types. (They made me think of the lecturing Nobel laureate I saw point with his microphone and talk into his laser pointer.) But contemplate such identity-confusion jokes in a society, Beard writes, “where formal proofs of identity were minimal: no passports, no government-issued ID … or any of those other forms of documentation that we now take for granted as the means of proving who we are.”

Such caveats about the possible impenetrability of ancient wisecracks turn up frequently throughout the text. But Beard also cites University of California, Berkeley, emeritus historian Erich S. Gruen, whose problem is with “the comprehensibility of Roman laughter, not the reverse.” And she quotes philosopher Simon Critchley of the New School: “The comedian is the anthropologist of our humdrum everyday lives.” She then extends his observation: “[The comedian] turns those of who see the point of the joke—those who get it—into domestic anthropologists too.”

Perhaps the superannuated material that still works, even under vastly different circumstances, nonetheless serves as a link between the shared anxieties of then and now—after all, identity theft is all the rage.

An academic sees a friend on the street and says, “I heard you died!” The friend says, “Well, you can see I'm alive.” And the academic says, “Yeah, but I trust the guy who told me more than I trust you.”