In the third and fourth seasons too. This is hardly unusual--the much-loved series Firefly/Serenity had a similar background. The belief that there are no aliens has a lot of validity and IMO makes human life all the more important, and makes the series all the more dramatic and poignant.
But it does offer several worlds that look just like the boreal forests of Vancouver Canada.
I saw very little of this in BSG, quite a bit of it in the Stargate series.
A cosmos of humanoid beings that all speak the same language!
Now I KNOW you are confusing BSG with Stargate. If there is only one intelligent species in the universe that colonized several worlds, as there is in BSG, then it's entirely posssible that they would speak the same language.
Me, I've had enough of "aliens" with prosthetics glued onto their foreheads. The stark and unforgiving universe of BSG was a refreshing change.
Ditto.... That is why I enjoyed those two shows.