A Test of Decision-Making: Nest Selection After Home Destruction
The experiment aimed to see how C. sanctus ants make decisions when facing conflicting interests. After their original nest was destroyed, they had to choose between two new options: a superior but small nest, which was dark, safe, and comfortable, and a larger but less appealing one, which was exposed, noisy, and uncomfortable.
Researchers controlled which ants could enter the better nest using chips with barcodes glued onto their backs, allowing only a few ants access. This created a situation where most ants had to stay in the inferior nest, forcing the colony to choose between prioritizing nest quality or staying together as a group.
Experimental design: The ants are able to choose between a good nest and a poor nest
Majority Concession: A Path to Consensus
In human and animal societies, consensus typically forms when individuals align with the majority's choice. However, in the C. sanctus experiment, things played out differently. When the majority had access to the better nest, the ants in the minority—stuck in the worse nest—didn't follow. Instead, the majority, despite having the superior option, chose to concede. In an unexpected "majority concession," they abandoned the better nest to join the minority, placing colony unity above individual gain.
This behavior is particularly notable for eusocial insects, where decisions usually prioritize collective welfare. In other species, like honeybees, decision-making relies on positive feedback, such as recruitment via pheromone trails that reinforce majority choices. In C. sanctus, however, positive feedback was more subtle. Ants tended to stay in a nest if many others were already there, but there was no strict recruitment pushing them to a specific nest. The queen’s presence, crucial for the colony’s survival, further boosted commitment to a nest.
Carpenter Ants with barcodes to identify with a camera
The Role of Size in Collective Decision-Making
Researchers discovered that colony size played a key role in how decisions were made. Smaller colonies struggled to reach a quorum—a tipping point for collective decision-making. On the other hand, larger colonies were more likely to split, with each group choosing a different nest. Colonies of intermediate size were the most likely to make unified decisions, even when faced with conflicting options.
Interestingly, C. sanctus doesn't follow the two-step process seen in other species, like Temnothorax albipennis, where recruiters guide the colony to a nest. Instead, C. sanctus decisions flow in a single step, dictated by how quickly ants enter a nest and how stable the colony remains there. This more fluid process allows for decision-making without strict recruitment systems or major behavioral changes.
Conflict Resolution and the Ant Model
The researchers manipulated the level of conflict by varying the ants’ access to the better nest, observing how majority concession played out. Even when most ants could benefit from the superior nest, they sacrificed it to keep the colony together in the inferior one. This effect became more pronounced over time, proving that majority concession was a stable outcome in C. sanctus colonies.
This example of compromise in nature may offer strategies for resolving seemingly unsolvable human conflicts. If ants can prioritize unity over personal gain, there are lessons to apply to complex social and political issues.
This study offers insights beyond ants, showing how social groups, including human societies, might benefit from majority concession. Typically, human decision-making involves individuals or groups sticking to their preferences, leading to division or stalemate. The ants demonstrated that unity, even at the expense of individual preference, can result in more stable outcomes.
In eusocial societies, where individuals prioritize the collective good, majority concession ensures survival. This contrasts with selfish behavior seen in other animals and human politics, where individual interests often dominate.
Conclusion: The Surprising Wisdom of Ants
Camponotus sanctus ants, despite their small brains, show surprising wisdom. When faced with choosing the best option or maintaining group unity, they prioritized cohesion, even at personal cost. This reveals a valuable lesson: majority concession can resolve conflicts and foster consensus, not only in ants but potentially in human societies as well.
These ants highlight how compromise and unity can overcome even the toughest conflicts of interest.
Further Reading
Pratt, S. C. (2005). Quorum sensing by encounter rates in the Ant Temnothorax albipennis. Behavioral Ecology, 16(2), 488–496. https://doi.org/10.1093/beheco/ari020
Pratt, S. C., Sumpter, D. J. T., Mallon, E. B., & Franks, N. R. (2005). An agent-based model of collective nest choice by the Ant Temnothorax albipennis. Animal Behaviour, 70(5), 1023–1036. https://doi.org/10.1016/j.anbehav.2005.01.022
Rajendran, H., Haluts, A., Gov, N. S., & Feinerman, O. (2022). Ants resort to majority concession to reach Democratic consensus in the presence of a persistent minority. Current Biology, 32(3). https://doi.org/10.1016/j.cub.2021.12.013
Tokita, C. K., & Tarnita, C. E. (2020). Social influence and interaction bias can drive emergent behavioural specialization and modular social networks across systems. Journal of The Royal Society Interface, 17(162), 20190564. https://doi.org/10.1098/rsif.2019.0564
If you'd like to support this blog and are interested in ant supplies, check out https://canada-ant-colony.com for all your ant needs (if you're in Canada)