Prosocial and antisocial choices in a monogamous cichlid with biparental care

研究グループは、中南米原産のペアが協力して子育てをする魚類、コンビクトシクリッドが実験下において“自分だけが餌を貰える選択肢(反社会的選択肢)”と“自分と自分の繁殖パートナーであるペアメスの両者が餌を貰える選択肢(向社会的選択肢)”の双方を提示した場合、自分とペアメスの両者が餌をもらえる向社会的選択肢を積極的に選ぶことを世界で初めて発見しました。また、餌を受け取る相手がライバルのオス個体や初めて会ったメス個体であった場合、向社会的選択の割合が変化しました。この結果は、同様の実験を行った霊長類の結果と類似しています。我々がもつ利他性(=他者に利益を与える性質)、ひいては「思いやりの心」の進化的起源は魚類にまで遡ることができるかもしれません。
Human society is cooperative and characterized by spontaneous prosociality. Comparative studies on endotherm vertebrates suggest that social interdependence causes the evolution of proactive prosociality. To test the generality of this hypothesis, we modify a prosocial choice task for application to the convict cichlid, Amatitlania nigrofasciata, a monogamous fish with biparental care and a strong pair bond. We also affirm that male subjects learn to favor prosocial choices when their mates are the recipients in a neighboring tank. When the neighboring tank is empty, males choose randomly. Furthermore, in the absence of their mates, males behave prosocially toward a stranger female. However, if the mate of the subjects is also visible in the third tank, or if a male is a potential recipient, then subjects make antisocial choices. To conclude, fish may show both spontaneous prosocial and antisocial behaviors according to their social relationships with conspecifics and the overall social context.