1) Intelligent people are only good at doing things that are relatively new in the course of human evolution. They are not necessarily good at doing things that our ancestors have always done, like finding and keeping a mate, being a parent, and making friends. Intelligent people tend not to be good at doing things that are most important in life. (First of all, I have to agree with this statement. We have always seen how brilliant people ended up being social outcast and we know that to be successful in life, we cannot live on an island. My interpretation is perhaps, intelligent people find it hard to connect with the rest because their thinking is different. Well, the challenge for intelligent people is perhaps to be less intelligent in certain situations and don't have to be correct in everything. Sometimes, life is to be enjoyed and some imperfections make this world such an interesting place).
2) ...... the law of evolution by natural and sexual selection, which states that the ultimate goal of all living organisms is reproductive success. All living organisms in nature are designed by evolution to reproduce and make as many copies of their genes as possible.
3) Savanna Principle: The human brain has difficulty comprehending and dealing with entities and situations that did not exist in the ancestral environment. (A principle coined by Satoshi Kanazawa).
4) The human brain implicitly and unconsciously assumes that all ostracism is costly, just as it assumes that all realistic images of people whom they see on a regular basis (and who don't try to kill or harm them in any way) are their friends, even when these people are on TV. (Basically, it states that our subconscious brain cannot differentiate between TV and reality and TV shows influence our life more than we know it).
5) No human traits have a heritability of 0; genes partially influence all human traits to some degree. (This is know as Turkheimer's first law of behavior genetics).
6) In fact, most personality traits and social attitudes follow what I call the 50-0-50 rule: roughly 50% heritable (the influence of genes), roughly 0% what behavior geneticists call "shared environment" (parenting and everything else that happens within the familty to make siblings similar to each other), and roughly 50% "nonshared environment" (everything that happens outside of the family to make siblings different from each other). It turns out that parenting has very little influence on how children turn out. (Striking isn't it and it seems to go against conventional wisdom? A parent is only important in providing the genes but how their children behaves are less influenced by their own behaviour but more by the external environment).
7) Among adults, intelligence is about 80% determined by genes.
8) Early childhood experience do affect adult intelligence, but they mostly function to decrease adult intelligence, not to increase it. (What Satoshi Kanazawa is saying is that intelligence is dependence on genes and no matter what you do during childhood will increase it. You can only fulfill your genetic capability).
9) ...... there are very few childhood experiences that will increase adult intelligence much more than their genes whould have inclined them to have.
10) So the more equal the environment between individuals, the more important the influence of genes become. (From point 9) above, childhood experiences, parenting, etc. is only important to ensure the child realise its genetic potential such as enough nutrition, opportunity for education, etc. but in many developed countries where child malnutrition is not a big problem and easy access to education is provided, the genes are more important compared to parenting. So, is it worth to have all the extra tuition classes?).
11) So contrary to popular misconception, genes largely (though, even for adults, never completely) determine intelligence.
12) Thus, according to the basic principles of quantitative genetics, the fact that general intelligence is highly heritable suggests that it is not very important for our survival and reproductive success........
13) This theory suggests that more intelligent individuals are better than less intelligent individuals at solving problems only if they are evolutionary novel. More intelligent individuals are not better than less intelligent individuals at solving evolutionary familiar problems that our ancestors routinely had to solve.
14) ...... this new finding can potentially explain why less intelligent individuals tend to enjoy the experience of watching TV more than more intelligent individuals do. (Darn, I enjoyed TV a lot. Well, after reading this book, it is not too good to be too intelligent. Just a little bit more intelligent is the best).
15) The more intelligent you are, the later you marry.
16) ...... more intelligent individuals are more likely to be stupid and do stupid things.
17) ..... liberals and other intelligent people lack common sense because their general intelligence overrides it. They think in situations where they are supposed to feel. In evolutionary familiar domains such as interpersonal relationships, feeling usually leads to correct solutions whereas thinking does not. (This explains why intelligent people is usually not good in relationship. They think too much and may sometimes feel relationship is a waste of time!).
18) More intelligent people reject the "simplistic" solution offered by common sense, even though it is usually the correct solution, and instead adopt unnecessarily complex ideas simply because their intelligence allows them to entertain such complex ideas, even when they may be untrue or unuseful in solving the problem at hand.
19) The average intelligence in society increases the marginal tax rate (as an expression of people's willingness to contribute their private resources for the welfare of genetically unrelated others) and, partly as a result, decreases income inequality. The more intelligent the population, the more they pay in income taxes and the more egalitarian their income distribution. (Interesting point isn't it?)
20) Just like the human mind, smoke detectors are designed to be "paranoid". This is known as the "smoke detector principle". (This principle states that our mind is designed to be paranoid because it is safer to err on the safe side. This is similar to the design of smoke detector where the smoke alarm tends to sound alarm even where there is no fire because the risk of the smoke detector not sounding the alarm when there is a fire will results in death while false alarm is a small inconvenience we pay for our survival. So, it is natural that our mind always picture the worst case scenario because that is how our brain has evolved from the days when we have to avoid being eaten).
21) Pascal's wager. The 17th-century French philosopher Blaise Pascal (1623-1662) argued that given that one cannot know for sure if God exists, it is nonetheless rational to believe in God. If one does not believe in God when He indeed exists (Type II error of false negative), one must spend eternity in hell and damnation. In contrast, if one believes in God when he actually does not exist (Type I error of false positive), one only wastes a minimal amount of time and effort spent on religious services. The cost of committing Type II error is much greater than the cost of committing Type I error. Hence one should rationally believe in God.
22) The woman decides when and with whom sex takes place; the man doesn't.
23) Contrary to popular belief, more educated women and women with more demanding careers do not have fewer children and are not more likely to remain childless.
24) ...... boys inherit their general intelligence from their mothers only, while girls inherit their general intelligence from both their mothers and their fathers.
25) So, women influence the general intelligence of future generations very strongly, through their sons and through their paternal granddaughters. (Choosing the right wife is very important!)
26) ..... intelligent people make more money and attain higher status in organizations, because capitalist economy and complex organizations in which most people work today are entirely evolutionary novel. (I don't quite agree with Mr. Kanazawa here. In modern complex organizations, some people are more successful if they are better in people skills which is not evolutionary novel as cavemen also need to have good people skills in order to survive and be the leader. As such, I would think that intelligent people will be successful in areas such as engineering, medicine, etc. while they are generally poor managers, politicians, etc. It is not surprising that we don't see many intelligent politicians. Hahaha).
27) ..... intelligent people lack common sense and have stupid ideas. (I would think stupid ideas here mean the idea is against acceptable social rules which intelligent people sometimes feel it is not necessary to follow).
In summary, the book is enlightening in a sense that it explains in a scientific and quantifiable manner why intelligent people are different compared to less intelligent people. It essentially drives home the message that intelligent people are good at doing things which are relatively new in the course of human evolution such as mathematics, science, etc. and because of that, may end up bumbling over evolutionary familiar tasks such as making friends, being a good parent, etc. It shows that intelligent people are typically different compared to others such as they have higher tendencies to be gay, is a night owl, drink and smoke more, etc., i.e. different. The book does seem to repeat the same themes towards the end which makes it a little less interesting once we get the idea that intelligent people are different.
