Actually, proboscis monkeys from Borneo and cows do have something in common: They both chew their cuds. Proboscis monkeys are reddish brown, long tailed primates known for their large noses. Babies are born with normal size noses, but by time they are adults, males can sport noses up to seven inches long. Proboscis monkeys are both arboreal and amphibious, which makes them good climbers and swimmers. But it's their leafy diets that have led to the evolution of a digestive tract very similar to cows. Cows and other ruminants have multi-chambered stomachs adapted for breaking down foods that are high in cellulose, a plant fiber that resists digestion. Cows use colonies of bacteria in one chamber of their stomach to cut apart the cellulose. They also chew their cud, which means they regurgitate their food from their stomach to their mouth and re-chew it to make the pieces smaller. This behavior helps break the food into smaller and smaller pieces so that bacteria can digest as much as possible.