To understand the behaviour of animals, we need to use different approaches, from observing them and making predictions, or taking a step further and looking into their DNA. Each species of animal has their own genes and genomes (whole DNA molecules)’ the environment influences how genes are expressed, resulting in different kinds of behaviour. This project was focused ono studying insects, specifically solitary sand wasps. They are interesting because two closely related species - Ammophila sabulosa and Ammophila pubescens - show contrasting behaviours related to how they care for their brood. One is mass provisioning, meaning that they feed the brood enough for their development and, the other is progressive provisioning, in which the mother feeds the brood for as long as it is developing. This indicates that one species has an extended period of parental care, which can be important for more complex behaviours to occur. Nowadays, there are genomic techniques to obtain genomes for any species, bringing the possibility of studying behaviour at the level of genes, and to understand how and why some species behave in a certain way. The overall objective of WASSUP was to understand the ancestral origins of pre-social behaviour (solitary behaviour) and determine the adaptations that could give rise to more complex, social behaviours. Studying ancestral origins of pre-social behaviour is important for society in general, because can help us to understand how cooperation evolved in other animal taxa, including in humans. This project also combined different methodologies, including the study of behaviour in a classical way in the field, recording changes in morphology by analysing images from electron microscopy and sophisticated molecular approaches, including genome sequencing and transcriptome analyses.