http://www.cracked.com/blog/the-4-fundamental-reasons-youre-asshole/
A good deal of this is due to that pesky primal mind that's only around because of the whole "evolution occurring over 2000 generations" thing. With the exception of the Bearjews, of course. With us Bearjews, evolution only occurs over three generations. It is also Lamarckian *grows second penis*.