WHY THINGS ROT

How dead plants and animals decay, and how living organisms rely on this natural process to survive

- WORDS SCOTT DUTFIELD

Rotting, better known as decay or decomposition, is a natural process where the organic molecules that make up a plant or animal start to break down into simpler and simpler substances.

There are several stages of decay, and the first is called autolysis. When the cells of an organism are starved of nutrients and waste products build up inside them, it causes a group of organelles (structures within a cell) called lysosomes to break open. Inside the lysosomes are digestive enzymes, which are typically used to battle pathogens. During autolysis, however, the lysosomal enzymes digest and break down the cell and its contents.

Autolysis isn’t restricted to the decomposition of an animal, it's also a helpful process for many animals that undergo metamorphosis. For example, when tadpoles are transitioning into their froggy form, the cells that make up their tails are ‘destroyed’ through autolysis and replaced with cells and tissue that give them their legs. Plants are slightly different in their initial decay. Lacking in the lysosome department, plants use similar digestive enzymes found in a large organelle called the vacuole within each cell.