Americans have been 'larger' for some time. We had trouble with AK47s after WW2, for example, because they were too small for the comparatively larger American

Americans have been 'larger' for some time. We had trouble with AK47s after WW2, for example, because they were too small for the comparatively larger American soldiers to wield comfortably. I don't think it's any more complicated than the fact that we eat more food for all of our lives.