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Tiny brained bees solve a complex mathematical problem

Visit the Royal Holloway University of London websiteVisit the Queen Mary University of London website

26 October 2010

Bumblebees can find the solution to a complex mathematical problem which keeps computers busy for days, even though they have a brain the size of a grass seed.

Bumblebee (Bombus terrestris) queen collecting pollen. Image: Nigel Raine

Scientists have discovered that bees learn to fly the shortest possible route between flowers even if they discover the flowers in a different order. Bees are effectively solving the ‘Travelling Salesman problem’, and these are the first animals found to do this. This research could inspire improvements to networks such as traffic on the roads, information flow on the web and business supply chains. By understanding how bees can solve their problem with such a tiny brain we can improve our management of these everyday networks without needing lots of computer time.

This work brings together researchers from both life and physical sciences to study how nature’s computers – brains – process complex tasks. Studying an insect with a tiny brain and comparatively great cognitive abilities gives researchers insight into the minimum circuitry required for solving difficult mathematical problems.

The teams from Royal Holloway, University of London and Queen Mary, University of London are funded by BBSRC, the Wellcome Trust and the Engineering and Physical Sciences Research Council following a call for multidisciplinary research proposals aimed at taking forward research in cognitive systems.

The research, due to be published in ‘The American Naturalist’ this week, also gives an insight into bumblebee behaviour. Bumblebees play a vital role in pollinating certain food crops and so an understanding of how they forage is important for future food security.

Solving the Travelling Salesman problem

The Travelling Salesman must find the shortest route that allows him to visit all locations on his route.

Dr Nigel Raine, from the School of Biological Sciences at Royal Holloway explains: "Foraging bees solve travelling salesman problems every day. They visit flowers at multiple locations and, because bees use lots of energy to fly, they find a route which keeps flying to a minimum.”

Computers solve this problem by comparing the length of all possible routes and choosing the shortest. However, bees solve it without computer assistance using a relatively tiny number of brain cells.

Professor Lars Chittka from Queen Mary's School of Biological and Chemical Sciences said: "In nature, bees have to link hundreds of flowers in a way that minimises travel distance, and then reliably find their way home - not a trivial feat if you have a brain the size of a pinhead! Indeed such travelling salesmen problems keep supercomputers busy for days. Studying how bee brains solve such challenging tasks might allow us to identify the minimal neural circuitry required for complex problem solving."

Co-author, Dr Mathieu Lihoreau adds: "There is a common perception that smaller brains constrain animals to be simple reflex machines. But our work with bees shows advanced cognitive capacities with very limited neuron numbers. There is an urgent need to understand the neuronal hardware underpinning animal intelligence, and relatively simple nervous systems such as those of insects make this mystery more tractable."

The team used computer controlled artificial flowers to test whether bees would follow a route defined by the order in which they discovered the flowers or if they would find the shortest route. After exploring the location of the flowers, bees quickly learned to fly the shortest route.

Dr Raine adds: “Despite their tiny brains bees are capable of extraordinary feats of behaviour. We need to understand how they can solve the Travelling Salesman Problem without a computer. What short-cuts do they use?”


Notes to editors

For more information or to arrange an interview with Dr Nigel Raine please call the Royal Holloway press office on 01784 44 3552/3967 or 07818 014 167.

High resolution images are available on request.

Lihoreau, M., L. Chittka and N. E. Raine (2010). Travel optimization by foraging bumblebees through readjustments of traplines after discovery of new feeding locations. American Naturalist: doi:10.1086/657042.

About Global Food Security

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