I'm not sure what you mean with "the food chain algorithm". If you are wondering why life forms eat other life forms: it's because other life forms can be interesting sources of biological building blocks and energy. read more
A “food chain” is the mechanism by which higher-ordered organisms are developed and sustained by the production of more disorder – the decomposition/digestion of other organisms. The “Chain” starts with the lowest organism forms – but may be extended in the energy sense to the solar energy received – to the highest organic forms in humans and animals. read more