When infants are involved in agonistic conflicts, male crested macaques (Macaca nigra) are more likely to respond to screams from their own offspring. This is the conclusion of a recent study led by behavioural ecologist Professor Anja Widdig from Leipzig University and the Max Planck Institute for Evolutionary Anthropology in Leipzig as part of the Macaca Nigra Project (MNP). The researchers studied the behaviour of crested macaques in the Tangkoko Nature Reserve on Sulawesi, Indonesia, over a 24-month period (2008 to 2010). A special issue of the International Journal of Primatology dedicated to these endangered animals has just been published. It marks the 17th anniversary of the Macaca Nigra Project.