Peter Singer, citing bioscientist-philosopher types, suggested in the 1993 edition of his book How Are We to Live that humans are 'programmed to care only about ourselves and our relatives', and that there might be 'an unwavering adherence to the Cardinal Rule; never ask a person to act against his own self interest'.
Singer went on, over years, to profile how the human ethical obligation extends our relational boundaries to other animals who inhabit the world we live in. He became one who chose not to consume animals in any direct or indirect way and who eschewed even undignified treatment of animals. Yes, Singer is vegan.
It is a relatively recent sociological development that many folk now understand that the animals we buy, breed and use for human purposes are entitled to be treated with respect and a personal acknowledgement that they can and do love as well as suffer, and that their needs and behaviours should be taken into account in terms of human lifestyle and consumer choices. Significant numbers of people support those who are willing to stand up for a duty to operationalise a basic concern for our shared home, including animal rights advocates. So long as they do not overly inconvenience the majority
On a philosophical level, men, women and policy makers have gone beyond an emotional understanding that witnessing/turning a blind eye to cruelty to other humans has a debasing effect, and so does toleration of cruel, frightening and brutal treatment of the animals that share our lives. This is no longer only a religious sensitivity.
Nietsche, for example, was driven insane when, on the streets of his Turin, he came across a crowd cheering on a man who was beating his cart horse to death. The philosopher beloved of Nazism (which misunderstood him), who had repudiated Christian compassion and claimed to be atheist, burst into tears and threw his arms around the suffering animal's neck, then was taken home where he stripped off his clothes and started raving.
In our more recent times, researchers have established a link between cruelty to animals and pathological developments in those who perpetrate it and go on to harm partners, children, and even commit random killings of strangers, if not sexual sadism.
When the ABC published footage of outrageously cruel treatment of healthy former racehorses in a Queensland abattoir, everyone, including the sensitive racing industry about to embark on the spring racing season, said