马尔萨斯陷阱是怎样炼成的？ Millennia of Poverty: If Not Malthusian, Then Why?   时间：3月5日（周三）下午2:00-3:30 地点：北京大学国家发展研究院朗润园 万众楼小教室 主讲人：吴乐旻，北大经济学院   Living standards were constant for thousands of years before the industrial revolution.  Malthusian theory is inadequate because it misses the fact that a dollar's worth of diamonds contributes less to survival and reproduction than a dollar's worth of grain. The constancy of living standards thus implies that growth was balanced between subsistence and surplus, something Malthus did not explain. To explain the balanced growth, I propose the theory of group selection. Selection of group characteristics, including culture and technology, goes on by migration and conquests. My new theory reinterprets why living standards declined after the Agricultural Revolution and stagnated afterwards, how the Industrial Revolution happened and where the prosperity of Roman Empire and Song Dynasty came from.