Although signs of empathy have now been well documented in non-human primates, only during the past few years have systematic observations suggested that a primal form of empathy exists in rodents. Thus, the study of empathy in animals has started in earnest. Here we review recent studies indicating that rodents are able to share states of fear, and highlight how affective neuroscience approaches to the study of primary-process emotional systems can help to delineate how primal empathy is constituted in mammalian brains. Cross-species evolutionary approaches to understanding the neural circuitry of emotional ‘contagion’ or ‘resonance’ between nearby animals, together with the underlying neurochemistries, may help to clarify the origins of human empathy.
In ongoing cycles of cultural-historical progressions, some have seen periodic signs of increasing empathy in human affairs, albeit with periods of intensified self-serving greed. Indeed, the fuller manifestation of empathy in humans may have promoted the emergence of human rights movements within the past two centuries of human cultural evolution, as exemplified by democratization, emancipation of slaves, together with women’s and gay rights movements. Indeed, perhaps our lateralized neocortical specializations have differential capacities for empathy, with the left hemisphere being more capable of promoting self-serving social dominance and arrogance, whereas the right is more pro-socially attuned toward altruism and empathic views of social life. Thus, the emergence of modern conceptions of fairness may still need to compete with our natural tendencies toward racially and kin-biased social favoritism. Clearly we have much left to learn about the ways of empathy. What we can be most confident of is that most neural knowledge about how empathy is constituted remains to be discovered.