Well the argument that Harari and others have made is that our hunter gatherers ancestors on the plains of East Africa, actually had more need for mental capaci

Well the argument that Harari and others have made is that our hunter gatherers ancestors on the plains of East Africa, actually had more need for mental capacity than we do today. You had to have your wits about you to not end up as lion's lunch and live long enough to pass on your genes. Also our brains may have been shrinking a little over the last ~30,000 years [1] http://en.wikipedia.org/wiki/Brain_size#Evolution http://en.wikipedia.org/wiki/Brain_size#Evolution [1]