Most of us have a vague idea that somewhere inside of us there are coils and coils of intestines, amazing passageways through which food passes in the process of digestion. But few people have a clear understanding of just how they work.

The length of the large intestine in animals depends on the kind of food they eat. Meat-eating animals have shorter intestines because there is less digestive work to do. The food they live on has already done part of the job of digestion. People who live on vegetables are supposed to have longer intestines than meat-eating people.