基金Acknowledgments We would like to thank Noa Pinter-Wollman for inviting us to write for a special issue that led us to consider these lines of thought. C.S. performed the experiments, simulations were performed by B.P., S.K. performed the statistical analysis and wrote the manuscript, S.A. performed the experiments, wrote the manuscript, and supervised the work.
基金We thank Dr S.J. Tan for identifying the ant species. We also thank the anonymous reviewers for providing valuable comments on earlier drafts of this manuscript. This work was supported by the National Natural Sci- ence Foundation of China （31000978） and the Fun- damental Research Funds for the Central Universities （2013PY007）.