I often think that the social ones are most hubristic of the sciences. Indeed, the motivation for the work taken up by psychology, political science, economics (etc) is (supposedly) to understand and improve ourselves and our living conditions. Frequently, I find this a source of profound dissatisfaction with my chosen field of study.
But, it's difficult to think of any science -- the biologies, the chemistries -- as anything more than another version of selfish pursuit. While in these the goal is to understand the non-human elements of the universe, the understanding we seek is similarly usually for our own advancement [link to bunnies with bleeding eyes here]*.
We debate the "unselfish good deed" endlessly. Perhaps we ought also to wonder of the "unselfish curiosity".
(I may have just given the physicists even more ego than they already have. But even their work is selfish if you consider that we'll all have to end up on Mars anyway.)