Cows graze in front of the Rosengarten mountain massif in northern Italy. Pasture grazing is practiced throughout the Alps. Matthias Schrader/Associated Press hide caption

Archaeologists believe that ancient farmers used pots made from these pottery shards to make cheese — a less perishable, low-lactose milk product. Nature hide caption

Tim Opper, of Cabot Cheese, inspects equipment that separates whey protein from sugar in the company's whey processing plant. Dan Charles/NPR hide caption