Sometimes a new experimental result suggests a very different way of interpreting older results. On a visit a couple of days ago to Ofer Tchernichovski's lab at Hunter College, I encountered a striking example of this effect.
The background is the experimental literature on zebra finch song learning. If one of these birds is raised in acoustic and social isolation, it never learns to sing a species-typical song, but rather continues to produce "proto-song", which is a sort of songbird equivalent of grunts and groans. In contrast, with a relatively brief exposure to an example of adult song during a "critical period" early in life, a bird will (later on) learn to sing properly, in fact imitating the tutor's song quite closely. Crucially, species-typical zebra finch song is made up of discrete "syllables" arranged in regular "motifs", whereas proto-song is relatively diffuse and non-categorical at all time scales.
A decade ago, I reported on some fascinating work from Ofer's lab showing that species-typical song can emerge over a few generations in a colony raised in acoustic isolation, never encountering any external adult models ("Creole birdsong?" 5/9/2008).
Now a newer experiment (Olga Fehér et al., "Statistical learning in songbirds: from self-tutoring to song culture", Phil. Trans. R. Soc. B 2016) adds a result that makes us think differently about the earlier work.
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