Back pain is a common trouble for modern people. When that feeling hits, we complain about being too busy at work, that the chairs aren’t comfortable enough, or that the gym wasn’t open lately. However, in the view of Endo Hideki, a professor at the University of Tokyo, this is first of all to blame for evolution-it stands to reason that the spine of quadrupeds should be parallel to the ground like a bridge, instead of standing up like humans to bear the weight of the entire upper body. Just like when eating a sandwich, the stuffing will always fall out. If the spine that was originally in a horizontal…