Animals (satta or tiracchàna) are sentient beings other than humans. The Buddha classified animals as being either born from eggs, born from the womb, born from water or spontaneously born (Samyutta Nikaya 3. 240). At other times he classified them as many-legged, four-legged, two-legged or legless. He said; ‘I know of no other class of things as diverse as the creatures of the animal world’ (Samyutta Nikaya 3. 151; Sutta Nipata 600). He also said that more beings are reborn as animals than as humans (Anguttara Nikaya 1. 36). Because animals have a limited capacity of comprehension and thus little chance to spiritually develop, and because the animal kingdom is dominated by the principle of ‘eat and be eaten,’ the Buddha considered it to be a distinct disadvantage to be reborn as an animal rather than as a human. Nonetheless, animals are sentient beings, capable of feeling pleasure and pain and thus worthy of sympathy and respect. Most religions say that we should love other humans. Buddhism broadens and universalises love by saying that it should be felt and expressed to all beings, however humble. The earliest legislation to protect animals from cruelty and to provide reserves for wild animals was drawn up by the Buddhist monarch Ashoka in the 2nd century BCE.
The Great Compassion – Buddhism and Animal Rights, Norm Phelps, 2004.