This CARTA symposium addresses the question of how human language came to have the kind of structure it has today, focusing on three sources of evidence. One source, which is discussed in these three talks, has to do with the ways languages get new structure not present in the language of the previous generation(s) of speakers or signers. Simon Kirby (Univ of Edinburgh) begins with an examination of Language Evolution in the Lab: The Emergence of Design Features, followed by Carmel O'Shannessy (Univ of Michigan) on Contact Languages and Light Warlpiri, and Ann Senghas (Barnard College) on Rethinking Recapitulation: Sources of Structure in Nicaraguan Sign Language. Recorded on 2/20/2015. (#29393)