Did humans become bigger or smaller over time?

Most geneticists believe that the improvement in childhood nutrition has been the most important factor in allowing humans to increase so dramatically in stature. The evidence for this argument is threefold:

First, the observed increase in height has not been continuous since the dawn of man; it began sometime around the middle of the nineteenth century. In fact, examinations of skeletons show no significant differences in height from the stone age through the early 1800s. Also, during World Wars I and II, when hunger was a frequent companion of the German civilian population, the heights of the children actually declined. They only recovered during the post-war years