The grand mediocrity of today——everyone being the same in survival and number of off spring——means that natural selection has lost 80% of its power in upper middleclass India compared to the tribe.
老师,破折号内独立主格结构做什么成分呢?句意上感觉应该是对mediocrity的解释说明,但独立主格不是不能做定语吗?