Quote Originally Posted by Squark View Post
But the problem is that, as I've said, The Tau's model doesn't scale up. They're still relying on slow FTL based courier ships for communication, and they don't have any problems as of yet with psykers, but with a growing gue'sva population, they're going to soon.
Oh, definitely, these are serious problems. I suspect, however, that if they don't develop some direct technological solution to long-range FTL jumps, they'll either utilise their growing knowledge of eugenics/gene-tailoring to deliberately create psyker tau, and/or find some way to neurologically condition human navigators/astropaths in a way similar to the imperial soul-binding process (which would kill two birds with one stone. They might also outsource FTL-jump duties, with suitable upgrades, to their nicassar acquaintances.) Of course, this all assumes that they survive the next few thousand years without being seriously molested.
Quote Originally Posted by The Glyphstone View Post
Except they do have a rigid caste system. I wouldn't doubt that within your caste, it's a 'be all you can be, find how you can best serve the Greater Good', but changing castes would be unthinkable.
Oh, no question. (Though that's a little like asking Michael Jordan if he wants to take up angel investing, or if Richard Branson has the urge to join the NBA.)

On a tangential note, I was reading Xenology recently (which is a very good yarn, actually,) and it had some fascinating *cough* 'conjectures' on the Tau's origins, purpose, and methods of social control.
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Basically, yes, it's pheremone-based mind control of the other castes, apparently genetically transplanted from the Q'Orl hive queens by the Eldar several thousand years ago, in a deliberate bid to create a socially-cohesive, passive-benevolent and naturally chaos-immune species sited as far from the imperial core as possible.