Communities evolve language spontaneously. Evidence of this is a school of deaf children (in Brazil IIRC) who were not taught sign language (due to lack of a teacher, due to budget). They developed their own, which became quite complex and of comparable sophistication to other human languages.

Taken with the conclusion of the submission that abstract thought requires language for its development, this leads us to the conclusion that abstract thought - far from an isolated activity - is a consequence of community.

It seems to me that it would be possible to develop abstract thought in isolation, but perhaps it would take a genius, in the same way that some mathematicians have developed mathematics in isolation, and it's just that it helps tremendously to have the cultural foundation to stand on. eg. I find it much easier to visualize abstraction, reference and so on, than to say it.