Choice within Genetic Predisposition - Why Night Owls Are More Intelligent than Morning Larks

The Intelligence Paradox: Why the Intelligent Choice Isn't Always the Smart One - Satoshi Kanazawa 2012

Choice within Genetic Predisposition
Why Night Owls Are More Intelligent than Morning Larks

I first became interested in circadian rhythm—why some people are night owls while others are morning larks—when I lived in Christchurch, New Zealand, for one year. I lived on Riccarton Road, one of the main thoroughfares in Christchurch. Down Riccarton Road from where I lived, there was a supermarket called Countdown that was open 24 hours a day, 7 days a week.

I would often go to Countdown to shop at three o’clock in the morning. Every time I did, I noticed that the place was crawling with Asian customers. This was before the recent explosion of Asian immigration to New Zealand, so Asians were still a small minority in Christchurch back then. I would not see many Asians in Christchurch most of the time, except at three o’clock in the morning in a 24-hour supermarket.

I began wondering then if this was because Asians were more nocturnal than other races. I had not thought about possible race differences in circadian rhythm until I lived in New Zealand and encountered a large number of Asians at three o’clock in the morning in a 24-hour supermarket. It was many years before I solved the mystery of late-night Asian shoppers.

Choice within Genetic Predisposition

Choice is not incompatible with or antithetical to genetic influence. As long as heritability (the proportion of the variance in behavior explained by genes) is less than 1.0, genes merely set broad limits, and individuals can still exercise some choice within broad genetic constraints.

For example, political scientists in the emerging field of genopolitics1 have discovered that two genes are responsible for predisposing individuals to be more or less likely to vote in elections.2 In other words, whether you choose to turn out to vote in any given election is partially determined by your genes. However, individuals can still choose to turn out to vote or not for any election, and there are environmental (nongenetic) factors that can predict their voting, such as whether the candidate you voted for in the last election won or lost.3 You become more likely to vote if you voted for a candidate who won in the last election, and less likely to vote if you voted for a candidate who lost in the last election.

Similarly, genetic influences and constraints do not preclude individual acquisition of values and preferences. Individuals can still choose certain values and preferences even in the face of genetic predisposition. In fact, Turkheimer's first law of behavior genetics,4 which I briefly introduce in Chapter 3, states that all human traits are heritable and influenced, at least in part, by genes. So if genetic predisposition is incompatible with personal choice, it would mean that humans have absolutely no choice to make at all. In reality, however, humans make choices in the face of genetic predisposition.

For example, both political ideology5 and religiosity6 have now been shown to have genetic bases. Some individuals are genetically predisposed to be liberal or conservative, or more or less religious. Yet, as we see in Chapters 5 and 6, more intelligent children are more likely to grow up to be liberal and less likely to grow up to be religious.7 Similarly, whether you are a night person or a morning person is partly genetically determined, but that does not mean that people still cannot consciously and volitionally choose to be a night owl or a morning lark.