Some years after they learned to farm, my villagers went through a long drought. They would plant and harvest, and the food supply would slowly grow, and then the crops would fail. This became a regular occurrence; it seemed every time I went into the game, the fields would be barren again and there would be a little mob of villagers hauling water from the well. Eventually crops would sprout, and they would harvest, but the yield was less and less each time. Several times the food supply went to zero for a while. All of my original villagers, now elders, weakened and died during this time, there were almost no births, and my population shrank by a third.

Then...it stopped. For the last 15 "years" or so, lots of food, lots of growth, lots of progress. So, if you are having trouble with keeping people fed, just hang in there!