Alright dammit...I'm doing both right now...in the final year of each. I am getting a BA and a BS, and most of the classes I have been taking lately are classes with all seniors and or grad students. Embryology, Advanced Mammalian Physio, Advanced Cell and Molec Bio, Biochem, none of these (NONE!) require half the work, creativity, critical thinking, or shifting away from "intuitive thinking" of any one of my Upper level lit classes.
You guys who are screaming how easy Humanities are, try writing a thesis on Ulysses that will be judged on an equal level with kids getting there PhD in early 20th century Irish Lit. I've done both the hard science and the crazy ambiguous lit, and I'm telling you, it's way easier competing with the PharmDs and Bio PhDs for an A in Embryology than writing at an A level in advanced lit courses.
To the guy who said he's taken lit and it's easy: just read and regurgitate: clearly you have not taken any lit classes with professors who give a f00k about what they are doing, because if you think you could get away with the teachers just being delighted that you did the reading you wouldn't make it through the first week of in-class writings in any upper level lit class at my Univ.
PS...and first I was a math major...wasted 2.5 years on it...got through advanced calc/linear algebra...did mega insane proofs...etc...even THAT was easier...imo.