The universe was a vast, empty, dark, and uncaring place. Then life happened, and the universe was changed forever. Only a teeny-tiny bit, but definitely different. Then again, the universe changes a teeny-tiny bit every second of every day. For instance, if someone were to get off the couch and randomly drink a glass of milk? Bam! One less glass of milk in the universe. Changed forever. Well, excluding any time-travel shenanigans, but anyone who puts a big old hole in the time-space continuum just to un-drink a glass of milk should really reevaluate their priorities. Unless, of course, they were attempting to prevent some massive catastrophe vis-a-vis said glass of milk. Such a scenario is by no means impossible, as one should never underestimate the importance of calcium.