The history of animal welfare is a story of expanding moral concern to include species once excluded, driven by improving scientific understanding of sentience.
The expanding circle of moral concern for animals tracks the expanding scientific understanding of sentience. Each new recognition — fish feel pain, crustaceans are sentient, insects may have some form of experience — raises the moral stakes of existing practices. The challenge for welfare advocates is translating scientific consensus into policy change, which has historically lagged decades behind the evidence. Keeping abreast of sentience science and connecting it clearly to welfare policy implications is essential work for moving the expansion of moral concern from the laboratory to the legislation.