Peter Singer argued a rat's suffering counts too, even if it isn't human

In 1975, Peter Singer coined the term "speciesism" to describe treating an interest differently purely because of what species holds it. His argument was simple and unsettling: if suffering is bad regardless of who feels it, giving human suffering automatic priority over animal suffering is no more defensible than favoring one race or sex.

— Peter Singer, Animal Liberation — HarperCollins, 1975
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