Distributed Decision-Making in Ants

Speaker:
Nigel Franks

Abstract:
Social insect colonies exhibit both individual and collective intelligence. I will illustrate this distributed decision-making with house hunting in rock ants. Each worker, among the 200 or so in a colony, has less than 100,000 neurones (compared to 10¹¹ neurones in humans) yet these ants employ the most sophisticated of all consumer strategies when choosing a new nest. Indeed, they can choose the best-of-N among alternative nests even though each has many different and important attributes. I will show how information can cascade through these social networks enabling colonies to benefit from both individual and collective intelligence. They use quorum sensing to facilitate collective intelligence and to achieve flexible speed accuracy trade-offs. They also appear, in effect, to plan for the future. Rock ants also fulfil all of the criteria of teaching. We have been able to show teaching through experimental manipulations and detailed quantitative analyses. Certain information is so valuable in their societies that individual workers conserve and propagate it by teaching others. Most recently, we have also demonstrated that these ants perform evaluations during teaching. Indeed, ants and humans are the only animals in which evaluative teaching has been demonstrated. I suspect that these tiny ants have larger behavioural repertoires than many if not most vertebrates. This begs the question; what are big brains for?