CUNEO - From Polybius’s words to Oxford’s equations. Barring an archaeological discovery, no one may ever be able to say with certainty which pass Hannibal crossed in 218 B.C. to bring an army of 46,000 men, 15,000 mules and horses, and 37 elephants into Italy. For years, scholars have focused on the Montgenèvre, Mont Cenis and Traversette passes in the Po Valley. Where the accounts — and legends — end, however, numbers now take over. A study published in the journal Proceedings of the National Academy of Sciences by Emilio Berti of the University of Jena and Fritz Vollrath of Oxford University examine the energy costs faced by the Carthaginians as they crossed the Alps. Using a biomechanical model to calculate the energy expenditure of humans, horses and elephants, the study concludes that only the Traversette route would have allowed Hannibal to bring all his war elephants into Italy.

The study also draws on research by William Mahaney of York University in Toronto, who traveled the passes between France and Piedmont, comparing Polybius’s accounts with the region’s geography and geology. At Pian del Re, about two hours from the Traversette Pass, he collected organic evidence consistent with the passage of an army 2,200 years ago. Berti and Vollrath wrote: “Philological and geomorphological analyses point to a route through the Traversette Pass. We focused on the energy costs of crossing the Alps, with particular attention to the elephants.” In the wild, elephants consume up to 200 kilograms of forage a day — an amount impossible to carry on an Alpine crossing. The Traversette route would have allowed for a faster ascent and descent, reducing the elephants’ overall food requirements. The calculations show that crossing the Traversette Pass would have required the army to expend 5.42 terajoules of energy, compared with 6.02 terajoules at Montgenèvre and 6.45 at Mont Cenis, providing the best balance of physical exertion, travel time and the ability to keep the elephants alive all the way into Italy.