Comparative cognition in three understudied ungulate species: European bison, forest buffalos and giraffes

Alvaro Lopez Caicoya,Conrad Ensenyat,Federica Amici,Montserrat Colell

doi:10.1186/s12983-021-00417-w

Alvaro Lopez Caicoya, Conrad Ensenyat + Show 2 more

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https://doi.org/10.1186/s12983-021-00417-w

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Abstract

BackgroundComparative cognition has historically focused on a few taxa such as primates, birds or rodents. However, a broader perspective is essential to understand how different selective pressures affect cognition in different taxa, as more recently shown in several studies. Here we present the same battery of cognitive tasks to two understudied ungulate species with different socio-ecological characteristics, European bison (Bison bonasus) and forest buffalos (Syncerus caffer nanus), and we compare their performance to previous findings in giraffes (Giraffa camelopardalis). We presented subjects with an Object permanence task, Memory tasks with 30 and 60 s delays, two inference tasks based on acoustic cues (i.e. Acoustic inference tasks) and a control task to check for the use of olfactory cues (i.e. Olfactory task).ResultsOverall, giraffes outperformed bison and buffalos, and bison outperformed buffalos (that performed at chance level). All species performed better in the Object permanence task than in the Memory tasks and one of the Acoustic inference tasks (which they likely solved by relying on stimulus enhancement). Giraffes performed better than buffalos in the Shake full Acoustic inference task, but worse than bison and buffalos in the Shake empty Acoustic inference task.ConclusionsIn sum, our results are in line with the hypothesis that specific socio-ecological characteristics played a crucial role in the evolution of cognition, and that higher fission-fusion levels and larger dietary breadth are linked to higher cognitive skills. This study shows that ungulates may be an excellent model to test evolutionary hypotheses on the emergence of cognition.

Highlights

Comparative cognition has historically focused on a few taxa such as primates, birds or rodents
Is the fission-fusion hypothesis only valid for primates, or can we extend it to other taxa which show a similar variation in social dynamics? Including other taxa is a powerful tool to test the limits of specific evolutionary hypotheses and understand whether different selective pressures are at work in different taxa
We used a Bayesian approach to assess how performance varied across species depending on the tasks (i.e. Object permanence task, Memory tasks with 30 and 60 s delays, Shake full and Shake empty task, and Olfactory task), whether the position of the food affected performance

Summary

Introduction

Comparative cognition has historically focused on a few taxa such as primates, birds or rodents. Throughout the history of comparative cognition, there has been a general bias to focus on a few specific species [1, 2], the inclusion of more diverse taxa can be essential to test specific hypotheses [3, 4]. Such a bias in the selection of study species has often reflected practical considerations (e.g. availability of subjects, maintenance costs) rather than clear research needs. There is still a long way to go to ensure a fair representation of different taxa in comparative animal cognition research [13]

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