I've been wondering what the most effective way is to rank up science and culture quickly and the answer is.... Supremacy! With Purity, I had 18 affinity at turn 350, with Supremacy I had it by 250. My science count was triple of my purity game. I had about 7-12 policies in all 4 trees. In my purity game, I was 7 affinities ahead. In supremacy, I was 13 ahead. (low difficulty, I'm still learning the game). It might be that I was playing better, but I'm sure I wasn't playing THAT better. It seems that almost every culture or science building is Supremacy related, to me anyways. Eh, anyone agree disagree maybe?