…which I keep wanting to type as “piranha”.

A mysterious commenter known only as “X” posted a link to this abstract.  I didn’t approve the comment, as the poster was too mysterious, but the article looks interesting, though in a somewhat dubious location on the internet.

However, one thing mentioned in the abstract seemed worth noting in particular: Everett makes many claims about how this one thing he sees in their culture (the Immediacy of Experience Principle, or IEP — gotta have your TLAs!) leads to all these grammatical features, or lacunae, really.  However, he provides no evidence of a general correlation; the linked-to article purports to show that there are other cultures with the same sort of “IEP” that do not have similarly constrained grammar.  That’s just the sort of research I want to see regarding Everett’s claims.