How was mechanical digestion discovered?

Digestion was first shown as a mechanical process in the 17th century, when Borelli carried out experiments on birds. He made them swallow objects that he then found crushed, deformed and broken. He concluded that the objects had been compressed and ground in the stomach.

So, in the 17th century, two types of mechanical transformation were recognised: the action of teeth and the stomach on food. Borelli compared jaws to pincers and the stomach to a vice.

How was chemical digestion discovered?

At around the same time, the scientist Réaumur was studying birds of prey. He placed a piece of meat inside an iron pipe and made a buzzard swallow it. When the bird regurgitated it, the pipe was intact but the meat was almost completely broken down. This proved that digestion occurred without grinding and was the first step towards understanding chemical digestion.