The expression of the emotions in man and laboratory animals

Similarities between human and animal emotions served as justification for both animal advocacy and animal experimentation in the later nineteenth century. Evolutionary kinship played a central role, at this time, in the competing arguments regarding the legal and moral status of nonhuman animals. During the vivisection debates of the 1870s, natural hierarchies were redrawn to include emotional sensitivity as a defining category of evolutionary status: a lack of sensitivity to animal suffering in humans could be regarded as regressive, while the highly developed sensitivities of particular animals earned them a special eminence. But it was this same cross-species sympathy that ultimately banished the experimental animal from the public gaze, as scenes from the laboratory were considered too disturbing to readerly sensitivity.