Naomi Lee and Ailís Cournane presented their talk "The journey, not the endstate: finding innovation in the dynamics of L1A" at Diachronic Generative Syntax (DiGS) 21, which was held June 5-7, 2019 in Tempe, Arizona.
They argue that the character of diachronic innovations is more driven by the learning strategies used by all children than by principles of economy. Specifically, they advance an unraveling approach to learning the morphosyntactic organization of features and show how an “unraveling” child could stay at earlier stages that mirror innovations that are both canonically economical (e.g. Romance determiners (head) from Latin demonstrative ILLE (specifier)) and noncanonical (e.g. innovating Somali’s bundling of gender and number on a single head).
Their slides can be found here.