Whereas human pro-social behavior is often driven by empathic concern for another, it is unclear whether non-primate mammals experience a similar motivational state. To test for empathically motivated pro-social behavior in rodents, a free rat was placed in an arena with a cagemate trapped in a restrainer. Within days, the free rat acted deliberately and quickly to open the restrainer and free the cagemate. Rats did not open an empty or object-containing restrainer. Rats freed cagemates even when rewarding social contact was prevented. When liberating a cagemate was pitted against chocolate contained within a second restrainer, rats opened both restrainers and in most trials, shared the chocolate. Thus, rats behave pro-socially in response to a conspecific’s distress, providing strong evidence for biological roots of empathy.
Empathy reflects the natural ability to perceive and be sensitive to the emotional states of others, coupled with a motivation to care for their well-being. It has evolved in the context of parental care for offspring, as well as within kinship bonds, to help facilitate group living. In this paper, we integrate the perspectives of evolution, animal behaviour, developmental psychology, and social and clinical neuroscience to elucidate our understanding of the proximate mechanisms underlying empathy. We focus, in particular, on processing of signals of distress and need, and their relation to prosocial behaviour. The ability to empathize, both in animals and humans, mediates prosocial behaviour when sensitivity to others' distress is paired with a drive towards their welfare. Disruption or atypical development of the neural circuits that process distress cues and integrate them with decision value leads to callous disregard for others, as is the case in psychopathy. The realization that basic forms of empathy exist in non-human animals is crucial for gaining new insights into the underlying neurobiological and genetic mechanisms of empathy, enabling translation towards therapeutic and pharmacological interventions.
In mammals, helping is preferentially provided to members of one’s own group. Yet, it remains unclear how social experience shapes pro-social motivation. We found that rats helped trapped strangers by releasing them from a restrainer, just as they did cagemates. However, rats did not help strangers of a different strain, unless previously housed with the trapped rat. Moreover, pair-housing with one rat of a different strain prompted rats to help strangers of that strain, evidence that rats expand pro-social motivation from one individual to phenotypically similar others. To test if genetic relatedness alone can motivate helping, rats were fostered from birth with another strain and were not exposed to their own strain. As adults, fostered rats helped strangers of the fostering strain but not rats of their own strain. Thus, strain familiarity, even to one’s own strain, is required for the expression of pro-social behavior.DOI:
http://dx.doi.org/10.7554/eLife.01385.001
Empathy is a phenomenon often considered dependent on higher-order
emotional control and an ability to relate to the emotional state of others. It
is, by many, attributed only to species having well-developed cortical circuits
capable of performing such complex tasks. However, over the years, a wealth of
data has been accumulated showing that rodents are capable not only of sharing
emotional states of their conspecifics, but also of prosocial behavior driven by
such shared experiences. The study of rodent empathic behaviors is only now
becoming an independent research field. Relevant animal models allow precise
manipulation of neural networks, thereby offering insight into the foundations
of empathy in the mammalian brains. Here we review the data on empathic
behaviors in rat and mouse models, their neurobiological and neurophysiological
correlates, and the factors influencing these behaviors. We discuss how simple
rodent models of empathy enhance our understanding of how brain controls
empathic behaviors.
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