Gilles De Meester is an FWO fellow and PhD student in the Functional Morphology Group at the University of Antwerp. He is interested in the evolution of animal cognition, especially in relation to environmental complexity. The central goal of his PhD is to study how cognitive abilities may be linked to the fitness of an individual and whether this link may differ between environments, using lizards as a study system. All animals are able to learn, remember and use new information, however, both within and among species, considerable variation in cognitive abilities exists. By studying this variation, biologists have tried to understand why, how and when cognition evolves within the animal kingdom, although much remains to be learned. Do animals (always) benefit from being able to learn? What are the costs and benefits of having a large brain? Are smart animals more attractive? Where else in the animal kingdom did large brains arise and how? Answering these questions is essential to unravel the evolution of animal cognition.