Urban areas and their surrounding environments present a challenge and an opportunity to other species. Some animal populations have adapted successfully, taking advantage of food stores and garbage as predictable trophic resources and man-made structures as secure living space. Archaeological and historical records show that this synanthropic adaptation began in prehistory, probably before the advent of agriculture, for example in some fox populations. Some commensal species show successful ethnophoresy, such as rodent populations that have accompanied human colonization of the planet. Once established, commensal animals form a part of the everyday scene for millions of people. Our response to them ranges from food handouts to extermination, from welcome neighbors to vermin, exemplified by our range of attitudes to urban pigeons. It is argued that commensal animals are an important social and educational resource that deserves further research and encouragement.