The Olympic motto is "Citius, Altius, Fortius." Faster, Higher, Stronger. And athletes have fulfilled that motto rapidly. The winner of the 2012 Olympic marathon ran two hours and eight minutes. Had he been racing against the winner of the 1904 Olympic marathon, he would have won by nearly an hour and a half. Now we all have this feeling that we're somehow just getting better as a human race, inexorably progressing, but it's not like we've evolved into a new species in a century. So what's going on here? I want to take a look at what's really behind this march of athletic progress.