21 October 2015

Ants can teach us how to plan infrastructure. Using mathematical modeling and field data, researchers at the Department of Mathematics at Uppsala University have found the basic rules that allow ants to build efficient and low-cost transport networks without discarding robustness.

We live in a world that is deeply interconnected. Nowadays, transportation networks are fundamental to the exchange of resources and information between different points and individuals. Every day we travel on roads, we use electricity and water that are carried from distant plants, we connect to the internet to read about facts happened on the other side of the world.

Ideally, we would like to be able to travel between cities on the shortest way possible, but sometimes we have to follow long detours. Thus network planners struggle to build transportation systems that are efficient and robust, but also not too expensive, trying to find the best compromise between competing design goals.

Searching for inspiration, researchers have turned towards nature, observing the spontaneous formation process of natural transportation networks, from ant trails to leaf veins. A two-year-long field study recently provided a large data set consisting of several trail networks built by the Australian meat ant to connect different nests spread over a wide territory.

‘What is amazing about these ants is that they don’t rely on engineering to plan their networks, yet they still are able to find a specific balance between cheapness, efficiency and robustness,’ explains Tanya Latty, researcher in biology at the University of Sydney.

Researchers from the department of mathematics at Uppsala University have developed a model to understand how these networks are formed. Using data and numerical simulations, they were able to identify a general mechanism of local cost minimization as the basic rule that leads to a balance between competing design goals. The study showed that when building a new nest, the ants connect it to the closest nest available and possibly to a tree, where the ants feed, if it is not too far away.

‘Once we have found what nature does, we have tried to apply the same simple rules to predict what would happen to man-made system, electric grids for example, if they were built by these ants,’ says Arianna Bottinelli, PhD student at Uppsala University.

It turns out that, when building a new suburb, it is sufficient to connect it to the closest city area to ensure that the whole power network will be relatively cheap but also quite efficient in the long run. Then robustness can be increased or decreased by changing the frequency with which new suburbs are connected to service centers, in this specific example to power plants.

‘It is a further step towards the understanding of nature and an attempt to use what we observe there to improve and advise the design of human-made systems,’ says David J.T. Sumpter, Professor at the Department of Mathematics at Uppsala University.

Bottinelli A, van Wilgenburg E, Sumpter DJT, Latty T. 2015 Local cost minimization in ant transport networks: from small-scale data to large-scale trade-offs. J. R. Soc. Interface 20150780. http://dx.doi.org/10.1098/rsif.2015.0780