I was introduced to the pitiable state of the tribes on the Andamans, quite some time ago. The same topic was dealt with at a seminar at the planetarium.
They are four/five known indigenous tribes in the Andamans. Said to be the first settlers in the Indian sub-continent, they associate us to our past. Scientists estimate that they've travelled from Africa fifty/sixty thousand years back.
The population of an important tribe(the great andamanese) is a mere twenty or so. There are high possibilities of them going extinct in a few years. A pity, really. A very crucial link is lost if this happens. It will be very tough to trace our lineage, or perhaps, even to foretell our lines of evolution.
This can be stopped. I last heard that the Indian Government are taking stringent steps in this regard(?). I hope that they survive. Into the future. A struggle, for our betterment.
ps: I found this interesting - http://www2.survival-international.org/related_material.php?id=92