Komodo dragons grew large on several Indonesian islands Animals living on islands tend to evolve into either giants or dwarfs in relation to their continental ancestors, reveals a new study. The analysis of more than a thousand land animal species shows that the so-called ‘island rule’ holds true for mammals, birds, reptiles, and, to a lesser extent, amphibians. Most so-called ‘rules’ in evolution turn out to be fairly limited in their scope and predictive power. From that perspective our results are exciting. Dr Joseph Tobias The research, published today in Nature Ecology and Evolution, was carried out by a team of scientists based at several European institutions, including Imperial College London.