People tend to perceive others as having a lower pain sensitivity if those others have experienced hardship or are part of a disadvantaged and minoritized group, including people of color or of lower socio-economic background. To learn more about the mechanisms behind and the downstream consequences of this hardship-to-pain bias, we used an experimental approach to measure people’s application of that bias on adults, children, and dogs. Results were that lay beliefs that hardship desensitizes individuals to pain were applied more strongly to adults and to children than to dogs. Perceived toughness mediated this differential effect, suggesting that general adaptation bias may not explain species-specific application of this hardship-to-pain bias. Control, paternalism, and responsibility over one’s environment did not significantly moderate the mediation, indicating “humanness” as an important factor and human-specific hierarchy justification as an important mechanism behind the hardship-to-pain bias.