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Mice, Empathy, and the Ethics We Ignore

Written by Kati Bertrand
April 2025

Two black mice touching noses© iStock.com/Georgejason

For centuries, humans have justified the use of mice in biomedical research under the false assumption that they are simple creatures, lacking the cognitive and emotional capacities found in other animals. However, recent findings from three independent experiments1–3 have uncovered that mice exhibit first-aid behaviors, actively assisting unconscious peers in similar ways to how humans respond in emergencies. Adding to the abundance of data that mice are more emotionally complex than some might think, evidence like this is shattering the notion that mice can be treated as mere test tubes, challenging long-held assumptions about rodents’ cognitive and emotional limitations and strengthening the ethical argument against their use in biomedical research.

An issue arises when the experiments designed to demonstrate these abilities in other animals contradict the very implications of the results. If mice possess such complex social behaviors and empathy-driven actions, continuing to subject them to invasive and distressing experiments like the ones described here becomes ethically indefensible and scientifically outdated.

“Acting without the expectation of compensation is called prosocial behavior,”4 a phenomenon driven by empathy. As Dr. Frans B.M. de Waal5 explains, “empathy allows one to quickly and automatically relate to the emotional states of others, which is essential for the regulation of social interactions, coordinated activity, and cooperation toward shared goals.” A fundamental requirement for empathy is “the ability to share the affective state of others.”6,7 While empathy was once considered a uniquely human trait, experiments have shown that mice, rats, and other animals also display empathic behaviors, including emotional contagion, observational affective learning, and prosocial actions, such as consolation and helping behaviors.

A recent behavioral experiment1 found that young mice actively and instinctively attempt to revive anesthetized peers by grooming and pulling their tongues to clear the airway. The authors noted that “[s]uch behavior likely plays a role in enhancing group cohesion and survival.”1

A chart showing mouse emergency responsesPhoto: Wenjian Sun et al. 2025.

Parallel experiments2,3 found that mice “engage in distinctive behaviors toward unresponsive conspecifics under deep sedation, characterized by intense contact and grooming directed at the sedated individuals’ head region, particularly the facial and mouth areas.”3 Mice can recognize when another mouse is unresponsive and respond with rescue-like behaviors.

A mouse administering first aidPhoto: Wenjian Sun et al. 2025.

Mice can also engage in the social transfer of pain,8 suggesting a capacity for sharing emotional states and influencing one another’s pain responses. This social transfer implies that mice engage in behaviors that fulfill the criteria for basic forms of empathy.

Panksepp and Lahvis9 previously found that the social dynamics of mice influence their empathic behaviors. In their experiments, mice housed in social settings displayed greater empathic fear-learning abilities than those who had been kept in isolation. Similarly, mice have been found to show empathetic fear responses through the recognition of shared experiences with conspecifics,10 indicating that relationships significantly affect emotional and behavioral responses in these animals. Mice with lower empathy levels than their peers are more reactive to physiological stress,11 reinforcing the notion that emotional capacities in mice are crucial for their social behavior and welfare. These findings and more demonstrate that mice have a more sophisticated level of emotional processing than previously acknowledged.

If mice display empathy and first-aid behaviors—key indicators of social intelligence— their capacity to suffer is much greater than previously acknowledged. Their ability to experience distress, empathy, and social bonding means that the pain inflicted upon them in laboratories is not just a physiological response but also an emotional and psychological trauma. These data require a common-sense response: The laws and guidelines governing the treatment and use of mice in experiments like the ones described above must change.

A mouse’s ability to recognize distress in others and respond with life-saving actions demonstrates that he or she is not a “furry test tube,” but a sentient being deserving of moral consideration. Such behavior should inspire more protection and better treatment, not more exploitation. Ironically, the very experimenters who document this empathy often fail to extend these findings to changes in their own practices. Instead, the evidence is used to rationalize more invasive procedures in the name of curiosity-driven experiments. Science can no longer justify a lack of sentience in other animals as the null hypothesis.

The question is no longer “Can we justify the use of mice in research?” but rather, “How can we justify continuing to do so when we know they are capable of distress, empathy, and care?”

Replacing the use of animals with humane, innovative, and human-relevant research methods not only advances our scientific objectives but also upholds our moral responsibility to act on what we know.

  1. Sun W, Zhang GW, Huang JJ, et al. Reviving-like prosocial behavior in response to unconscious or dead conspecifics in rodents. Science. 2025;387(6736):eadq2677. doi:10.1126/science.adq2677
  2. Cao P, Liu Y, Ni Z, et al. Rescue-like behavior in a bystander mouse toward anesthetized conspecifics promotes arousal via a tongue-brain connection. Science Advances. 2025;11(4):eadq3874. doi:10.1126/sciadv.adq3874
  3. Sun F, Wu YE, Hong W. A neural basis for prosocial behavior toward unresponsive individuals. Science. 2025;387(6736):eadq2679. doi:10.1126/science.adq2679
  4. Ueno H, Suemitsu S, Murakami S, et al. Rescue-like behaviour in mice is mediated by their interest in the restraint tool. Sci Rep. 2019;9(1):10648. doi:10.1038/s41598-019-46128-5
  5. De Waal FBM. Putting the altruism back into altruism: The evolution of empathy. Annu Rev Psychol. 2008;59(1):279-300. doi:10.1146/annurev.psych.59.103006.093625
  6. de Waal FBM, Preston SD. Mammalian empathy: Behavioural manifestations and neural basis. Nat Rev Neurosci. 2017;18(8):498-509. doi:10.1038/nrn.2017.72
  7. Klein AS, Gogolla N. How mice feel each other’s pain or fear. Science. 2021;371(6525):122-123. doi:10.1126/science.abf5940
  8. Smith ML, Asada N, Malenka RC. Anterior cingulate inputs to nucleus accumbens control the social transfer of pain and analgesia. Science. 2021;371(6525):153-159. doi:10.1126/science.abe3040
  9. Panksepp JB, Lahvis GP. Differential influence of social versus isolate housing on vicarious fear learning in adolescent mice. Behavioral Neuroscience. 2016;130(2):206-211. doi:10.1037/bne0000133
  10. Sanders J, Mayford M, Jeste D. Empathic fear responses in mice are triggered by recognition of a shared experience. PLoS One. 2013;8(9):e74609. doi:10.1371/journal.pone.0074609
  11. Laviola G, Zoratto F, Ingiosi D, et al. Low empathy-like behaviour in male mice associates with impaired sociability, emotional memory, physiological stress reactivity and variations in neurobiological regulations. PLoS One. 2017;12(12):e0188907. doi:10.1371/journal.pone.0188907

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Mice, Empathy, and the Ethics We Ignore