I am fascinated by biological organisation and, in particular, its characteristic combination of robustness and flexibility. Evolution through natural selection has resulted in a hierarchy of organisational levels such as macro-molecules into cell organelles, cells into organs, organs into organisms or organisms into societies. The key to understanding biological organisation is through the link between two such successive levels of organisation: between, for example, the neuron and the brain, the tooth and the mouth cavity or the ant and the ant colony. This link between levels of organisation is often the result of interactions. The interactions between biological entities at the same level with one another and with the environment lead to another organisational level that is more than the sum of its parts. I study the link between the individual and the society in terms of behaviour. From evolutionary perspective, this is the latest level of biological organisation and the components are not as integrated as in earlier levels. Hence, it lends itself more easily to experimentation. My work is carried out in collaboration with colleagues from different disciplines using different approaches.