Rats and mice are far more cognitively sophisticated than commonly assumed. Understanding their social bonds, play behavior, and emotional complexity has direct implications for how we treat them in research.
The cognitive sophistication of rats and mice creates a direct and urgent welfare implication for the over 100 million used in research annually. Animals capable of empathy, laughter, contagious fear, and metacognition are not mere biological machines but sentient beings whose social and emotional needs have real welfare significance. Individual housing — the default in many research facilities for reasons of experimental control — deprives highly social animals of the conspecific contact they need for psychological wellbeing. The consequent chronic stress not only harms welfare but confounds research results, since stressed animals show different biological responses than unstressed ones. The most welfare-positive and scientifically rigorous choice is pair or group housing with appropriate enrichment, departing from individual housing only when scientifically required and approved through welfare review.