-- (Margaret Kimball) Allen’s long, ascetic face, with narrow eyes and raised eyebrows, lends him an expression of perpetual seriousness that belies his sardonic good humor. This is an Englishman whose appreciation of pathogenic bacteria derived in part from Monty Python (Q: What’s brown and sounds like a bell? A: Dung!) and who named the goldfish in his backyard pond Nosey, Scrumpy, Motley, Blind Pew, Spunky and William. “I hand-feed William peas and garlic," Allen says. “He won’t eat mealworms. He’s too discerning."

He was delighted last year when the Belfast Telegraph headlined a front-page feature about his research team: QUEEN’S DUNG BOFFINS GET TO BOTTOM OF HANNIBAL ALPS RIDDLE IN PIECE OF 2000-YEAR-OLD POO. (“Boffin," Allen kindly explains, is British slang for a scientist with technical expertise.) The accompanying cartoon depicted him holding an enormous roll of toilet paper. “Ever since that article appeared, people all over the world have been mailing me fecal samples," Allen says. He pauses. “I’m only kidding!"

He learned to jest as a lad in Bristol, hometown of the great conceptual jokester Banksy. “I was a rather confused child," Allen says. He toyed with the idea of becoming a paratrooper and then a train driver before deciding that “a career in science would be cool." His earliest memories of scientific endeavor include designing a burglar alarm for his bedroom (age 6), leaving homemade stink bombs on his neighbor’s doorstep (age 8) and “looking at bits of unpleasant things" under the microscope (age 9). “Little did I know that the latter would later become my main source of income," he says.

Chris Allen reads a passage about Hannibal from Polybius’ Histories while climbing in the French Alps. (Tomas van Houtryve)

While in college—he has a doctorate in microbiology from the University of Warwick—Allen realized that he could have a lot of fun and generate research pay dirt by “doing things that other people hadn’t thought of yet": Hence his current research interests are as diverse as understanding the microbial ecology defining the Anthropocene, corpse microbiology, hunting for microbial genetic signatures associated with ancient comet impact events and, of course, solving the Hannibal Enigma through metagenomics—the study of micro-organisms by direct extraction and cloning of DNA.

Allen is the latest British boffin to argue for the Traversette. The earliest was a naturalist named Cecil Torr, who in his 1924 book Hannibal Crosses the Alps tells us that as a teenager he set out, fruitlessly, to find traces of vinegar used, after fires were set to heat rock, in fracturing boulders that blocked the Carthaginian army. (A procedure, notes Cambridge classical scholar Mary Beard, “which has launched all kinds of boy-scoutish experiments among classicists-turned-amateur-chemists.") Still, Torr was branded a Hannibal heretic and the route he recommended was dismissed as untenable. His theory was largely ignored until 1955, when Gavin de Beer took up the cause. In Alps and Elephants, the first of several books that the evolutionary embryologist wrote on Hannibal, he displayed something of the Kon-Tiki spirit with the claim that he’d personally inspected the topography. For centuries only traders and smugglers had used the Traversette; scholars avoided it not just because the climb was so dicey, but due to what de Beer called “the ease with which triggers are pulled in that area."

De Beer gave the topic the scrubbing it deserved, consulting philologists, invoking astronomy to date the setting of the Pleiades, identifying river crossings by plotting seasonal flow, analyzing pollen to estimate the climate in 218 B.C., and combing through historical literature to tie them to geographical evidence. All who have played the Hannibal game know they must discover in their chosen pass a number of specific features that correlate with the chronicles of Polybius and Livy. One by one, de Beer demolished the wealth of alternatives. “Of course," he added disarmingly, “I may be wrong."

F.W. Walbank certainly thought so. The eminent Polybian scholar refuted de Beer’s conclusions on linguistic and timeline grounds in “Some Reflections on Hannibal’s Pass," published in Volume 46 of The Journal of Roman Studies. His 1956 essay began with the all-time Carthaginian money quote: “Few historical problems have produced more unprofitable discussion than that of Hannibal’s pass over the Alps." Walbank, who seemed inclined toward either Col du Clapier or Mont Cenis, was later dressed down by Geoffroy de Galbert, author of Hannibal and Caesar in the Alps, for allegedly misreading Polybius’ Greek. (If you’re keeping score, de Galbert is a Col du Clapier man.)

Indeed, in the spirited tradition of academic sport, where the gloves come off when citations are misattributed or a middle initial is misidentified, every theory of the Punic passage withers under a rebuttal. “In online forums, the squabbling can get fairly vicious," Allen reports. “All I can say is that scientists get really emotionally connected to what they are doing. I know we are often portrayed as being cold and clinical, but we are human beings like everyone else, with all the difficulties that encompasses."

Hannibal’s daring push across the Alps soon entered into the realm of legend. “In this case all tales were eclipsed by reality," Livy states. (Alamy)

Allen came to the work of de Beer by way of Bill Mahaney, a professor emeritus at York University in Toronto and an outspoken exponent of the Traversette. A couple of years after the two began corresponding in 2009, Mahaney invited Allen on a field trip to a mire below the pass.

In contrast to the mild, placid Allen, Mahaney is an irascible mountain man who could start an argument in an empty room. He’s 76 now and hobbled by arthritis that restricts his mountaineering, but his talent for jawing knows no bounds. Mahaney has accumulated a vast fund of tales in his expeditions to grand peaks on every continent, particularly the Alps, where over the last 15 years he has assessed possible Punic routes by surveying every pass on the French-Italian border. His quest has yielded two books: Hannibal’s Odyssey: The Environmental Background to the Alpine Invasion of Italia and The Warmaker, a novel whose lusty dialogue could have been airlifted from the 1960 film Hannibal, a Victor Mature blockbuster taglined “What My Elephants Can’t Conquer, I Will Conquer Alone!"

Chowing down with Mahaney at his home in the Toronto suburbs is a little like getting hit by a train: If you survive, you’ve got a lot to talk about afterward. “Hannibal wasn’t just a brilliant strategist and military tactician," he says, brandishing a muffin like a boxing glove. “He understood the complexity of human behavior, that command involved more than giving orders and intimidating men to follow him—it involved compromise and shrewd leadership. He impressed the enemy with his courage and daring and swordplay, fighting on the front lines, wading into the thick of battle. He wasn’t some Roman consul sitting behind the troops. During the Italian campaign Hannibal rode an elephant through a swamp off the Arno and lost the sight in his right eye from what was probably ophthalmia. He became a one-eyed general, like Moshe Dayan."

A Roman emperor once wrote that everything we hear is an opinion, not a fact; and everything we see is a perspective, not the truth. Which pretty much sums up our understanding of Hannibal, a key figure of European history—if not for what he achieved, then at least for the traumatic effect he had on Roman memory. We know very little about him for certain. And as Mahaney points out, nearly all of what is known about him and his fantastic gamble over the Alps comes through the filter of his embittered adversaries.

The First Punic War (264-241 B.C.) was fought over control of the strategic islands of Sicily and Corsica. The Sicilians embroiled the rising republic of Rome in their squabbles with Carthage and transformed a minor dispute into an armed conflict fought largely at sea. “When the Carthaginians had to fight, they hired mercenaries, though they had their own elite commanders," Mahaney says. During the final years of the conflict, their leader in Sicily was Hamilcar Barca, from a prominent family of Carthaginian aristocrats. Alas, the Romans pulled an upset victory and eventually Carthage not only lost its claims to Corsica and Sardinia, but was left saddled with a debt, which the Barcas helped to pay off by establishing a Carthaginian empire in silver-rich Spain. Determined to see Carthage restored to its former glory, Hamilcar made his eldest son, Hannibal, swear lifelong enmity to the republic.

The Romans declared war on Carthage again in 218 B.C., by which time Hamilcar had been killed in battle and Hannibal was in charge of the army. In the opening phase of PWII, Hannibal consolidated and expanded control of the territory in Spain. Since the Romans had mastery of the seas, he attempted the unthinkable: attacking their homeland by surprise from the supposedly impregnable north. Hoping that the sight of rampaging elephants would scare the enemy, he assembled his animal train and headed east. “Sitting on his cot Hannibal could feel the rhythm set in motion by his troops as his squadrons marched past," Mahaney writes in The Warmaker. In a flurry of purple prose, he adds: “The empty water jug, like a fortress, teetered slightly on the shelf, reacting very differently than water. Yes, he thought, my army will be like a fluid enveloping all stationary objects, rolling like a wave over them."

Accustomed to the warmth of Africa and New Carthage, the liquid legions flowed through Spain, France and the trackless, snowbound Alps, holding at bay the Allobroges, a mountain tribe that set ambushes, slung arrows and rained great rocks upon their heads. “It’s a wonder Hannibal didn’t get a spear in his back," allows Mahaney. “By the time he delivered his speech at the top of the pass, many of his mercenaries were either dead, starving to death or suffering from hypothermia. Yet Hannibal didn’t lose a single elephant."

Exactly which pass that was, of course, has been a source of endless dust-ups among Hannibalologists. One thing they all seem to agree on is a set of environmental parameters that any prospective pass must fit:

A day’s march from a narrow gorge, where Hannibal’s men walked single file and tribesmen hidden on cliffs began their assault.

A “white" or “bare" rock place, where some of his fleeing troops spent that night.

A clearing on the approach near the summit, surrounded by year-round snow, large enough to camp an army of at least 25,000. And a point on the summit where the troops could gaze down to the Po River Plain.

A steep, slippery descent on the Italian side that’s hemmed in by precipices and bottoms out in a valley suitable for pasturing horses and pack animals.

Mahaney contends that the Traversette is the only pass that fulfills these criteria. Then again, Patrick Hunt—a historian and archaeologist at Stanford, former director of the university’s Alpine Archaeology Project and author of the new biography Hannibal—makes the same claim for the Col du Clapier. They’ve both studied soil chemistry and postglacial weathering of moraines along the passes. Both have scanned satellite images, scrutinized lichen growth and rock weathering rates, and modeled historical glaciation to help envision how the land today may have changed since Hellenistic times. And both think the other’s inferences are a lot of Hannibaloney.

In 2004 Mahaney discovered a two-tiered rockfall—caused by two separate accumulations of rubble—on the Traversette’s Italian frontier. The fallen mass, he says, jibes with Polybius’ description of the rock debris that impeded the elephant brigade’s path to the valley. “None of the other passes have a deposit on the lee side," he insists.

Chris Allen (in the French Alps) admits his quest is quixotic: “Our project is a bit like Hannibal’s traverse. It’s something new that nobody wanted to do—or even thought of doing." (Tomas van Houtryve)

Hunt counters that the Col du Clapier also has multilayered rockfalls, having buried much of the later Roman and earlier Celtic terraced roadbed under multiple layers of talus. He adds that “rockfall" is a mistranslation of the Greek word for landslip, and that Polybius was actually referring to a slender track along a mountainside interrupted by a drop where the slope had fallen away. “Polybius states Hannibal’s forces slipped through fresh snow to ice below from the previous winter on the initial descent," he says. “Mahaney tries to get around the lack of snow traces on the Traversette by reading snow and ice as firn, or frozen ground. This is not philology, this is creative wishful thinking."

Hunt thinks the Traversette’s descent would be narrow for elephants; Mahaney, who observed the beasts traversing Mount Kenya when he climbed there, thinks they’d have had no problem taking the high road. And while Hunt thinks the Traversette would have been too high and the terrain too treacherous for humans, Mahaney thinks the Col du Clapier would have been too low and the terrain not treacherous enough: “An army of nuns could walk straight down off the Clapier into Italy," he says, snickering like a schoolboy who’s just discovered there’s a city in France named Brest. “Hunt implies that the Traversette may not have been passable in Hannibal’s time, but I don’t think he has a grasp of what Hannibal’s warriors actually looked like. You wouldn’t want to meet them on a dark night, anywhere. They were crack troops who could cover 20 miles a day while lugging food and weapons."

Curiously, there’s no record of Punic armaments of any kind having been recovered from the various passes. Nor have archaeologists found evidence of Punic burials or Carthaginian coins. Mahaney is seeking financial backing to conduct further research at the Traversette mire, a site, he says, that might benefit from the use of ground-penetrating radar. “But first we’d need permits from the French government. And the French, for all intents and purposes, invented ruban rouge," Mahaney says, using the French term for red tape. Chris Allen notes with gentle irony: “In the absence of a radar scan of Hannibal’s Mire, the parasites we dug up might well be the most intact relics of his passing army."

Hannibal’s Mire lies in a soft, enclosing gorge about the size of a soccer pitch. The sides of the surrounding hills splinter into a small stream that purls through moss and ferns and peat hags. For all the stark drama—shadows scudding across cliffs, sudden shafts of sharpening air, clouds draping heavily over peaks—the bog creates a sense of serenity. Absorbed in a fragile trance, Allen studies a knot of tadpoles wiggling in a marshy puddle. A faint scent of mint fills the air. At last Allen says, “Our purpose here is to try to strengthen the pool of scientific data. That’s really all we can do. It’s up to the modern historians to back it up."

Ancient historians wrote that after crossing the mountain pass, Hannibal’s army spent 15 years marauding through the Italian peninsula. “His men slaughtered 50,000 Roman soldiers at the Battle of Cannae in 216 BC," says Allen, “but they never took Rome." Starved of supplies and fresh troops by his rivals back in Carthage, Hannibal was recalled home to defend the city-state against the depredations of Roman general Publius Cornelius Scipio—and defeated at the epic Battle of Zama. He was living in exile near present-day Istanbul when Roman legionaries tracked him down. He died in 183 B.C. of poison, self-administered—his alternative to being apprehended and paraded in chains through the streets of Rome. Thirty-seven years later Carthage was captured and razed.

Allen and his crew have analyzed sediment from this boggy area just below the Col de la Traversette. (Tomas van Houtryve)

“Think of what Hannibal accomplished over six months," says Allen. “He did something that nobody had even imagined doing. Wouldn’t it be something if, on this spot, he marshaled his forces and inspired them to succeed against the odds?" In the spirit of Hannibal, scientists have taken a novel approach to a thorny problem.

The research Allen oversees at Queen’s University Belfast is slow-going and funding is negligible. But Allen believes the project has all sorts of implications for environmental DNA, the study of telltale plant and animal genetic materials collected from soil and other substrates. “Over the long term, environmental microbiology could be the key that helps solve many of the big problems—from new drug discovery to energy and carbon capture. We all know how important soil is, but the surprising thing is we hardly understand it. Metagenomics is the tool that will allow us to finally optimize our interaction with soil."

Allen can envision combining meta-genomics with pretty much any scientific discipline, from engineering to theoretical physics to medicine. “I’ve been inspired by our Clostridia findings to attempt a study of ancient samples of Clostridia difficile from humans," he says. A hospital super-bug resistant to most antibiotics, C. difficile mainly afflicts the elderly, but younger people are falling prey to it and the disease has become more severe, accounting for nearly 30,000 deaths in the United States in 2011. “It seems there are definite genetic changes in some modern strains. If we turned the clock back 2,000 years and pulled out human strains [of Clostridia] from the Hannibal Mire, would they have the same genetic changes? Would there be differences we don’t know about, leading to new hypotheses? Would these differences allow us to find new ways to protect patients from infection? Conceivably. We are in the middle of a scientific revolution that most people don’t even realize is happening. Maybe this is the dawn of the Metagenomic Age."

So far, the research team has isolated five tapeworm eggs from the muck. Genome sequencing of the eggs is high on Allen’s to-do list. “The more genetic information we have, the more precise we can be about what type of animal left the droppings and perhaps its geographic origin," he says. If Allen can link the DNA to a horse that comes only from Africa or Spain, he’ll be satisfied that he’s on the right track. If he can link it to an elephant—improbable considering that horses are spooked by pachyderms and require separate space to forage—he would really be in business. Or possibly not. Hannibal’s kid brother Hasdrubal followed him 11 years later and brought war elephants along, too. As you might have anticipated, there’s no clear consensus on whether Hasdrubal took the exact same path, so finding an elephant tapeworm wouldn’t definitively prove the route was Hannibal’s.

Still, Allen is tickled by the prospect of exhuming a tapeworm from elephant dung during his next field-research trip, on the Italian side of the Traversette. Wouldn’t it be funny, he quips, if the real poop on Hannibal’s alpine trail were revealed in a scoop of real poop?

Source: © Copyright, The Smitsonian Magazine, July-August 2017. Reproduced without permission