Decreasing Intellectual level of Human and destruction of Human Civilization periodically

Whenever in past Human Civilization started to adopt luxurious think. Development of human brain get stop and Intellectual level in human beings decreases gradually generation by generatio and vanished. As per our common thinking, it seems that currently we are living in advance society and technically modern society. It also seems that we are living in technologically most advance society of Humans. But most probably, we might be wrongs about this. Because, so many historical evidences are there in India and around the world which evident that there were most technologically advance human civilization in past and highly intellectual human had build the most advance insfracture. Probabaly, they might be not only advanced in architecture and infrastructure building, they might be also advance in medicinal treatment, surgical treatment, engineering and mathematics. But here is the question that how these civilization get destroyed. Answer is that whenever any civilization develops technologically and human intellectual increases. 

Human civilization get luxurious and get lazy. It is the law of nature that intellectual of human brains develop when brain struggle to achieve success. When brain try to do complex work and solves problems, brain give extra effort to generate highly intellectual cells in mind and becomes more intellectual than previous generation. Due to continuous sturggle with nature and stuggle full life, gradual increase in intellectual increases generation by generation. It means that struggle in life make human brain more systematic and develop capability to tackle problem. Slowly, when humans start to build machines and human dependency on machines increases. Human brain gives less effort and intellectual of human brain slowly decreases from one generation to another generation. At the end, human forget to tackle problem and either regain intellectual by struggling with problems and regrow of human civilization or human civilization get vanished. Several time, probably it had happened in past on earth. From zero, a human civilization grow and at peak point of human intellectual, humans get luxurious and go in comfortable mode. Then, from that peak point, downfall of human intellectual occurs. It seems like a Chromatography of growth and down fall of Human civilization periodically and repeatable. It like a cycle of nature.