The development and evolution of song culture
Similarly to humans, songbirds learn their songs by imitating adult individuals and achieve complex vocal behaviour gradually during a sensitive period in early development. Young birds raised in complete social and acoustic isolation produce abnormal songs. However, when young birds are tutored with such abnormal songs in an iterated learning paradigm, the songs gradually, over a few generations, acquire normal, wild-type characteristics. Wild-type song culture, therefore, appears without any wild-type cultural input just as a result of social transmission. To find the minimum requirements for the emergence of wild-type song features, we tutored young birds with their own developing songs, removing any external song input. This experiment externalised the song feedback and is similar to iterating the song learning within a single generation. Young birds trained with their own songs in such a manner produced much more normal songs than their isolate brothers. Therefore, wild-type song features can appear without any external song input just by the iterated learning of the bird’s own developing song. To introduce the developmental aspect of my work, I will briefly talk about the emergence of combinatorial capacities in zebra finches, which shares basic features with other songbird species and human babies.