But I don't think a suggestion that there's such a thing as 'universal grammar' is the same as a suggestion that syntactic grammar is going to be shared between

But I don't think a suggestion that there's such a thing as 'universal grammar' is the same as a suggestion that syntactic grammar is going to be shared between all languages. As I understand it, the unifying element of UG could be simplistic or complex - which might make the concept hard to discredit. I'm pretty certain that syntactic grammar would be the result of cultural and genetic evolution. If both factors are available to influence a language's evolution, I'd imagine that both would be likely to influence the way that language evolves to some degree. I think the most interesting part of this mystery is how the brain's capacity for language might be innate - and in this respect, looking at the resultant artefacts produced by this processing might be a bit like looking at the remnants scattered around the room after a party the night before. Perhaps the concept of a shared UG is more relevant to the process than the resulting syntactic structure?