Edward Payson Evans in "Evolutional Ethics and Animal Psychology", published in 1898, was critical of anthropocentric psychology and ethics, which he argued "treat man as a being essentially different and inseparably set apart from all other sentient creatures, to which he is bound by no ties of mental affinity or moral obligation". Evans argued that Darwin's theory of evolution implied moral obligations towards enslaved humans and nonhuman animals, asserting that these obligations not only implied that cruelty to slaves must be mitigated and that slavery be abolished, but also that nonhuman animals need more than just kind treatment; they require rights to protect them and that would be enforced if violated. Evans also contended that widespread recognition of the kinship between humans and even the most insignificant sentient beings would necessarily mean that it would be impossible to neglect or mistreat them.