Sensitivity to the emotions of conspecifics, through empathy or emotional contagion, is important to facilitate smooth communication with others and is necessary for an adaptive social life. As opposed to antisocial behavior, prosocial behavior is socially desirable behavior that benefits other individuals (Eisenberg and Miller 1987). In humans, even 1-year-old children show prosocial behavior toward others when they recognize sadness in other people (Bischof-Kho¨ler
1991; Warneken and Tomasello 2006, 2009; Zahn-Waxler et al. 1992). Although this kind of ability has previously been thought to be specific to humans (Fehr and Fischbacher 2003) or at least to non-human primates (Clay and de Waal 2013; de Waal 2008; Preston and de Waal 2002), it was recently reported that rodents can show emotional contagion (Atsak et al. 2011; Chenet al. 2009; Langford et al. 2006), can demonstrate the effects of social cues on learning (Akyazi and Eraslan 2014; Knapska et al. 2010), and can display signs of cooperation (Rutte and Taborsky 2007; Viana et al.
2010).