Professor Bernard Quatermass: The will to survive is an odd phenomenon. Roney, if we found out our own world was doomed, say by climatic changes, what would we do about it? 
Dr. Mathew Roney: Nothing, just go on squabbling like usual. 
Professor Bernard Quatermass: Yes, but if we weren't men?

http://www.imdb.com/title/tt0062168/quotes?qt=qt0169941

(1967 movie)