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Lecture 4: The Rise and Fall of Civilizations Did other civilizations show a rise and fall in intelligence? If this is true of our civilization, we suggest it should be true of others. They should have ‘risen’ when intelligence was selected for and declined as this selection slackened. We investigate whether or not this was the case with Rome. We find, based on quantitative evidence such as secular per capita genius, that the rise and fall of Rome is best partly explained by changes in average general intelligence. As it was rising, intelligence was being strongly selected for and it developed into a democracy: trust and democracy being positively associated with intelligence. By the middle period of Rome, there was widespread use of contraception as a highly rational people took control of their lives. This was mainly used by the more intelligent, something that was even noted at the time. Thus, we see Rome’s collapse into corruption, violence and dictatorship. Christian civilization, we find, reached a higher level before it collapsed because it had lost the knowledge of contraception. We find that the rise and fall of Islamic and Chinese civilization can be explained in a similar way, in part. In addition, Christian and Islamic societies engaged in conquest, meaning intense group selection for genius, so aiding the growth of these civilizations. With high civilization, group selection for genius relaxed. We discover clear quantitative evidence for the rise and fall of these civilizations being partly explicable in terms of intelligence variation and factors which altered selection for intelligence, such as climate change: with warmer and milder climates reducing selection for intelligence and helping to explain civilization decline. We also look at other potentially contributory factors, such as pollution, but find that they are less parsimonious. Does this mean that civilizations always rise and fall? We wonder if this means that all civilizations will always behave in this way. We look at the three main understandings of history: the Fall (the best civilization is in the past), the Progressive (civilization will keep progressing forever), and the Cyclical (civilizations rise and fall). We meet the many Classical and Medieval scholars who advocated what is known as ‘Social Cycle Theory,’ including the Islamic scholar Ibn Khaldun. He argued that civilizations begin as religious, they reach a level of too much luxury, they lose their religiousness and they collapse. We then meet modern advocates of these models. Advocates of Social Cycle Theory, all argue that civilization leads to society becoming so rational that it loses its sense of existential purpose, the more intelligent limit their fertility, and it is displaced or collapses. We find evidence that the essence of this is intelligence. Civilizations grow as they are religious and they select for intelligence. At a certain high point, the intensity of selection for intelligence is reduced due to the high standard of living and the most intelligent limit their fertility and take control of their lives, no longer seeing children as random gifts from God. The intelligence of the society decreases, despite its population growing, and civilization eventually collapses. In addition, the growing society becomes highly group selected, producing lots of geniuses, which benefit the group in competition with other groups. Civilization makes conditions less harsh, reduces the group selection pressure, and so reduces the levels of genius. In contrast, modern advocates of the progressive theory argue that the technological revolution means that we have broken free of this cycle. The so-called ‘law of accelerating returns’ means we will eventually reach incredible levels of technological sophistication and artificial intelligence will come to drive civilization beyond the biological. We leave it to the student to decide which is more persuasive - there being positive and negative points to both perspectives.
