Can we understand modern humans without considering pathogens?

Throughout our evolutionary history, humankind has always lived in contact with large numbers of pathogens. Some cultural traits, such as sedentarization and animal domestication, have considerably increased new parasitic contacts and epidemic transitions. Here, we review the various phenotypic traits that have been proposed to be affected by the highly parasitic human environment, including fertility, birth weight, fluctuating asymmetry, body odours, food recipes, sexual behaviour, pregnancy sickness, language, religion and intellectual quotient. We also discuss how such knowledge is important to understanding several aspects of the current problems faced by humanity in our changing world and to predicting the long-term consequences of parasite eradication policies on our health and well-being. The study of the evolutionary interactions between humans and parasites is a burgeoning and most promising field, as demonstrated by the recent increasing popularity of Darwinian medicine.