Assessment of help value affects reciprocation in Norway rats

Abstract

Wild-type Norway rats reciprocate help received in a well-replicated experimental food-giving task, but the criteria to appraise the received help's value are unclear. We tested whether quality or quantity of received help is more important when deciding to return help, and whether partner familiarity and own current need affect this evaluation. We experimentally varied recipients of help's hunger state, and familiar or unfamiliar partners provided either higher caloric food (enhanced quantity; carrots) or food higher in protein and fat (enhanced quality; cheese). Reciprocation of received help was our criterion for the rats' value assessment. Familiarity, food type and hunger state interacted and affected help returned by rats. Rats returned less help to familiar partners than to unfamiliar partners. With unfamiliar partners, rats returned more help to partners that had donated preferred food (cheese) than to partners that had donated less preferred food (carrots), and they returned help earlier if they were satiated and had received cheese. With familiar partners, food-deprived rats that had received cheese returned more help than satiated rats that had received carrots. Our results suggest that Norway rats assess the received help's value based on its quality, their current need and partner familiarity before reciprocating received help.

Reciprocal altruism in Norway rats

“…Both male and female wild‐type Norway rats were found to help same‐sex conspecifics in accordance with the direct reciprocity decision rule by giving more help, for example food donations and allogrooming, to previously cooperating partners than to previously defecting partners (Dolivo & Taborsky, 2015a; Engelhardt & Taborsky, 2022; Rutte & Taborsky, 2008; Schneeberger et al., 2012; Schweinfurth & Taborsky, 2018b, 2018c, 2020; Schweinfurth et al., 2017, 2019; Stieger et al., 2017; Wood et al., 2016). Female Norway rats were shown to help according to the quality of help they received (Dolivo & Taborsky, 2015b; Engelhardt et al., 2023; Kettler et al., 2021) and their partner's need (Schneeberger et al., 2012, 2020; Schweinfurth & Taborsky, 2018a). Female Norway rats were shown to help social partners according to the direct reciprocity decision rule rather than according to copying by imitation (Engelhardt & Taborsky, 2022).…”

Evidence suggesting that reindeer mothers allonurse according to the direct reciprocity and generalized reciprocity decision rules

“…Direct reciprocity was reported across several taxa, including mammals [ 28 , 29 , 56 – 62 ] (e.g. vampire bats, Desmodus rotundus [ 57 , 58 ] and Norway rats, Rattus norvegicus [ 29 , 59 – 61 , 63 – 65 ]), birds [ 20 , 21 ], fishes [ 54 , 55 ], and microorganisms [ 66 , 67 ]. Generalized reciprocity was reported in humans [ 68 , 69 ], female Norway rats [ 60 , 64 , 70 ], dogs, Canis familiaris [ 71 ], capuchin monkeys, Sapajus apella [ 72 ], however generalized reciprocity was not supported in male Norway rats [ 64 , 73 ], long-tailed macaques, Macaca fascicularis [ 74 ] and in vampire bats [ 57 ].…”