Is the Karmic Retribution for Killing by Animals Heavier Than That by Humans?

The creation of unwholesome karma and killing karma is primarily governed by the mind consciousness (意根) and carried out by the six consciousnesses. However, the mental activities of the mind consciousness alone also constitute karma, known as mental karma (意业). This too plants seeds, bears karmic fruit, and results in the suffering of birth and death within the cycle of rebirth. Among the three types of karmic actions—physical, verbal, and mental—mental karma is the most fundamental and the heaviest, because physical and verbal actions are directly commanded and controlled by the mental actions of the mind consciousness. Physical and verbal actions arising from greed, hatred, and delusion instigated by the mind consciousness are termed intentional actions. Actions not arising from greed, hatred, and delusion instigated by the mind consciousness are termed unintentional actions. Intentionally created unwholesome karma carries grave and profound sin, constituting inherent sin and karma (性罪性业). Unintentionally created unwholesome karma carries minor sin and lacks inherent sin and karma.

Animals preying on each other falls between intentional and unintentional action. It is driven purely by hunger, without murderous intent or hatred. The karma created is relatively minor, the unwholesome karma is slight, lacking inherent sin and karma. They simply incur a debt that will need to be repaid in the future. Once an animal's period of unwholesome karma concludes, it may be reborn as a human. If a human then creates unwholesome karma, they will again fall into the three lower realms to undergo retribution. Sentient beings thus revolve within the cycle of birth and death in the six realms, and the karmic actions performed during a human life are the primary determining factor.