[DougWebb]

They obviously didn't evolve there independently from other humans. They and the other tribes have common ancestry, and a common root language. I doubt anyone knows about inter-tribal contact through those 60,000 years that could have kept the languages from diverging too much.

[x1798DE]

According to the current Wikipedia article on the Sentinelese language [1], it is not mutually intelligible with Onge. This is more like what I would have expected from a strictly xenophobic and (presumably non-literate) tribe, but it doesn't square with the account in the article...

[1]. https://en.wikipedia.org/wiki/Sentinelese_language