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Cognitive performance is linked to group size and affects fitness in Australian magpies

Nature volume 554, pages 364367 (15 February 2018) | Download Citation

Abstract

The social intelligence hypothesis states that the demands of social life drive cognitive evolution1,2,3. This idea receives support from comparative studies that link variation in group size or mating systems with cognitive and neuroanatomical differences across species3,4,5,6,7, but findings are contradictory and contentious8,9,10. To understand the cognitive consequences of sociality, it is also important to investigate social variation within species. Here we show that in wild, cooperatively breeding Australian magpies, individuals that live in large groups show increased cognitive performance, which is linked to increased reproductive success. Individual performance was highly correlated across four cognitive tasks, indicating a ‘general intelligence factor’ that underlies cognitive performance. Repeated cognitive testing of juveniles at different ages showed that the correlation between group size and cognition emerged in early life, suggesting that living in larger groups promotes cognitive development. Furthermore, we found a positive association between the task performance of females and three indicators of reproductive success, thus identifying a selective benefit of greater cognitive performance. Together, these results provide intraspecific evidence that sociality can shape cognitive development and evolution.

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Acknowledgements

We thank E. Russell and the late I. Rowley for access to their life-history records, and for allowing us to continue work on their Guildford magpie population; A. Wolton for help with fieldwork; R. Lymbery for help with statistical analyses; and N. Boogert and A. Young for helpful comments and discussion. This work was funded by an ARC Discovery grant awarded to A.R.R., A.T. and M. B. V. Bell, and a University of Western Australia International Postgraduate Research Scholarship and Endeavour Research Fellowship awarded to B.J.A. A.T. received additional support from a BBSRC David Phillips Fellowship (BB/H021817/1).

Author information

Affiliations

  1. Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia

    • Benjamin J. Ashton
    • , Amanda R. Ridley
    •  & Emily K. Edwards
  2. Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Treliever Road, Penryn TR10 9FE, UK

    • Alex Thornton

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Contributions

B.J.A., A.R.R. and A.T. conceived and designed the study. B.J.A. wrote the manuscript. B.J.A. and E.K.E. carried out data collection. All authors discussed results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Benjamin J. Ashton or Amanda R. Ridley or Alex Thornton.

Reviewer Information Nature thanks T. Bugnyar and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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    This file contains Supplementary Results and Discussion, Supplementary References and Supplementary Tables 1-26.

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DOI

https://doi.org/10.1038/nature25503

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