Hard to grow and having only a short harvest period, the elusive Alba truffle fetches around $7,500 per kilogram. At those prices, the Italian pensioners who gather them would be fools to trust that famed truffle hunter, the pig. Not only is using pigs now illegal, because they disrupt the ecosystem and endanger truffle reproduction, but they also tend to hog their discoveries. Instead, dogs lead the anziani through the Piedmontese forests in search of white gold, as a new documentary shows. The fungus has long been a fabled delicacy. Juvenal, the great Roman satirist, speculated that truffles were created when Jupiter flung a thunderbolt towards an oak tree. Lord Byron, a poet, was said to keep one on his desk, finding the aroma stimulating. Yet despite high demand for tartufi, “The Truffle Hunters” records a vanishing way of life. Deforestation and climate change is affecting supply, while the ancient ways are dying off with the hunters.