I'm not sure how astonishing this is or should be. Apparently (according to the narrative of events set up for us by the Western observers) when people of our culture meet the Pirahas, there is culture shock and misunderstanding. And beneath the observers' narrative there is even more real misunderstanding, because they use experimental methods that are way off beam (even if fun) like King Kong or animated monkeys on a screen.

(BTW, the Pirahã man was simply watching the floating monkey head and wasn't responding to the audio cues could quite probably be construed as universal, given the standard behaviour of Western TV-viewer couch-potatoes).

Haven't these people lived for generations out of mind in the same very specific environment, isolated from other cultures? Aren't our "universals" built from migration and mixing, confrontation and cooptation of cultures? Haven't anthropologists already placed these questions high on their list of priorities?

But the biggie :

what about the possibility that language may not have anything particularly universal.

I think you're referring to Chomsky, and what you mean is universal structural characteristics. Does it matter if Chomsky is wrong?

Much more, what if it is not specially different from other animals comprehension except for the cultural part.

Er, what cultural part would that be? Animals have culture, at least, they have learned behaviours. What we have no evidence for is that they have symbolic language. The Pirahas do. Their language may be oral and pitch-based, and tied to their immediate environment in space and time, (I won't say simplified because we might well find that they possess a wealth of distinct terms for what it is useful for them to distinguish), but words for river, this tree or that plant, this animal or that person, are symbolic (without going into terms like "spouse", which is perhaps what you mean by the "cultural part"). Whether language has universal structure as Chomsky proposes is one thing. That symbolic language is universally human is another.

Thanks for a fascinating diary. (It's got a date on it... ;))