Slight side track, if I may...
Are you thinking intelligent methane based life?
Well, as far as we know today, if life exists it will eventually become sapient. That is with an n=1, however.
But, right now I'm just thinking about what life would be like if it would be possible at that temperature. If methane is the universal solvent in that biosphere, there are some challenges as it is non-polar. Water being a polar molecule is more able to solvate proteins and other charged molecules. The methane may need to be a solution of methane and chloro-methane to improve solubility.
You still have access to CHNO with methane, ammonia and water. Energy can be extracted from acetylene, perhaps stored as a olefin polymer, reduced to ethylene. Ammonium hydrate could be a proton source for that. Sulfur and chlorine chemistry may be expressed more. You can still have carbon chains for macromolecules, but anything like DNA may have to be individually smaller or shorter. Maybe substituting aluminum for calcium, so that critters have berlinite bones rather than hydroxyapatite.
I think that musing about a Titan situation would be more plausible than life developing in a gas giant atmosphere. As was mentioned elsewhere, having a "world ocean" cuts down on the chances of life since there is no means of concentrating base chemicals for life to spontaneously arise. I think that would apply to a gaseous ocean as well as a liquid one. On Titan, we have seen the lakes and streams.
I recently read Uller Uprising
, by H. Beam Piper. Between the novel and the journal articles I've been thinking of non-standard life forms.
Sir Chaos wrote:
I think the best bets for moderating temperature variation would be small axial tilt (to reduce seasonal variation), fast rotation (to reduce variation during the day/night cycle) and a dense atmosphere (to increase heat retention and thus decrease temperature drop during night/winter).
I agree. It's a very narrow range. Freezing point depression and boiling point elevation only get you so far. The lakes freeze from the bottom up, though. That makes them lose heat quicker, but the liquid phase is accessible longer.