The First Rule, do unto others as you would like to be done unto, is the rule of conduct between those who would collaborate, regardless of species. If I eat Joe, his friends may suffer the loss of Joe s good will towards them. Thus threatened, they will eat me. Complex creatures such as humans are actually mobile mounds of symbiotic microorganisms. Ecological trading of goods and services between your cells gives you thought.
Cells don t have compassion.
They have do or die genetic programming. This includes an immune system. They cannot survive the failure of their symbiotic city of cells. Genetic replication is bound by the economics of finite resources. Given a barren planet and a single replicating gene in a puddle of volcanic acids, a monocology can persist only until it is easier to eat the original eater rather than the original food.