Abstract: Human communication has been largely influenced by the global popularization of social network sites such as Facebook over the past decade. From PCs to mobile phones, humans can now communicate in ways never before experienced during our history on Earth; moreover, sites like Facebook are providing a novel platform for engaging in female intrasexual competition. Through cyberbullying, selfies, and Facebook “stalking,” females are engaging in traditional strategies of intrasexual competition (i.e., self-promotion, rival derogation, mate manipulation, and competitor manipulation) in an evolutionarily novel social environment. This chapter examines what is new about social interactions that take place online and what is an artifact of our evolutionary heritage. Additionally, it argues that the self-promoting material that Facebook users post to the site is indicative of underlying fitness; therefore Facebook postings are an example of a modern-day extended phenotype.