Tim Little wrote:
 > With all the jokes about K'kree burgers, the
 > serious question remains of just how different the biospheres of
 > different planets in Traveller are at the biochemical level.

If Universal World Profiles are truly representative of all habitable
planets, not all that much.

If you can walk around in shirtsleeves and eat local produce without
dying from anaphylaxis or overwhelming infections in short order - or
the native life doesn't experience similar unpleasantness when dealing
with your shed skin, hair, bacteria, etc. then there's not a lot of
biochemical difference.

 > Were there distributions of life between the stars, say a billion or
 > two years ago?

Is the Orion Arm reasonably homogenous from a chemical perspective?
Maybe Earthly style biochemistry is the easiest to form given the
available ingredients.

 > Also what are the chances that a transition to a completely different
 > universe so variant from our own that lightspeed doesn't even apply,
 > happens to be survivable by fragile chemical meatbags in their
 > natural state?

Did Grandfather create jump space, or did he just find it and figure out
how part of how it worked?

Knapp wrote:
 > I always wonder just how diverse humans would be after a dark night
of say 1000 years.

I agree with Bruce Johnson - without intervention 1000 years isn't long
enough. 50-60 human generations with pessimistic mutation rates far in
excess of the ~70 per generation average[1] won't cut it.

With regard to the beginning of this thread - the only way I can
reconcile the concept of a carbon-silicone biochemical transition is
something like this:

Some rare worlds have two biochemistries develop in parallel, rather
than one type filling all available niches early in a world's history.

So the silicone-based life interacts sporadically with the carbon-based
stuff e.g. silicone stuff is based underground, and quakes or volcanism
allow contact with surface or ocean dwelling carbon-based life.

The real evolutionary action is evident at the level of micro-organisms
- both in diversity and speed.

Multicellular life forms either develop symbiotic relationships, or die
off from crippling autoimmune complications as a host tries to eject an
intruder...

Rob O'Connor
[1]http://www.ncbi.nlm.nih.gov/pubmed/22345605