TITLE: Facial Resemblance Affects Behaviour and Attributions

Two lines of reasoning predict that highly social species will have mechanisms to in-fluence behaviour towards individuals depending on their degree of relatedness. First, inclusive fitness theory (Hamilton, 1964) leads to the prediction that organisms will preferentially help closely-related kin over more distantly-related individuals. Second, evaluation of the relative costs and potential benefits of inbreeding suggests that the degree of kinship should also be considered when choosing a mate. In order to be-haviourally discriminate between individuals with different levels of relatedness, or-ganisms must be able to discriminate cues of kinship. Facial resemblance is one such potential cue in humans. Computer-graphic manipulation of face images has made it possible to experimentally test hypotheses about human kin recognition by facial phe-notype matching. I show that humans respond to facial resemblance in ways consistent with inclusive fitness theory and considerations of the costs of inbreeding, namely by increasing prosocial behaviour and positive attributions toward self-resembling images and selectively tempering attributions of attractiveness to other-sex faces in the contex