Very interesting thank you. One confusion I still have relates to the Slavic languages. You equated the inanimate class with the neuter and explained how the grammatical feminine gender emerged within the animate class. But in Polish, Russian and so on the inanimate objects can be of all three genders, for example stół, szafa, jajko (all inanimate, no prizes for guessing which one is feminine). Similarly, animate words can be of all three genders too, with the neuter reserved for the children, e.g. kogut, kura, kurczę. Any idea how that emerged?