Here's my (late) answer to Bryan Caplan's challenge
can you write an economically sound answer to the question "When Did Life For the Poor Get Better?" that a five-year-old could understand? 150 words or less!
At no point in time did life "start" to get better for the poor. At most any point in space and time, those who were "poor" were much better off than the poor of two centuries before -- the earlier society could not have fed them all, and would have treated survivors more harshly. Since the dawn of man, tremendous progress has come from inventions, be them technical or social. Techniques that seem primitive today, like heavily salting food so it doesn't rot, once transformed the life of generations. So did trading routes across regions with different resources: salt, game, wood, metal. Or money as a universal intermediate for barter between remote strangers. Or techniques and social mores that ensured increased hygiene. Countless innovations have always served to improve life for everyone. Even slavery was once progress for the poor victims -- over anthropophagy. Obstacles to progress are political oppression and superstition.