To live for a long time, you need to study well, son!
Smart and diligent children live longerAlexander Markov, "Elements"
For further observations, a part known as the "six-day sample" was selected from this huge sample. It included children born on the first days of even months (February 1, April 1, etc.). The six-day sample includes 1208 people (618 women, 590 men). Up until 1963, when these people turned 27, sociologists regularly visited them, interviewed them, and monitored the course of their lives. Then this work stopped, but in the XXI century, a group of psychologists from the universities of Glasgow, Edinburgh and Southampton took up the "six-day sample" again in earnest.
In 2004, scientists published preliminary results based on the analysis of part of the "six-day sample" (Deary et al., 2004. The impact of childhood intelligence on later life: Following up the Scottish Mental Surveys of 1932 and 1947 // Journal of Personality and Social Psychology. V. 86. P. 130–147). The results indicated that children with higher IQs live longer on average, but this conclusion was based on a small amount of data and did not take into account many additional factors.
In a new article published on October 9 in the journal Psychological Science, researchers rely on the entire "six-day sample" and take into account a large amount of additional information for each person in the sample.
In addition to the IQ index determined in 1947, data collected three years later were taken into account, when teachers were asked to evaluate all children in the "six-day sample" according to the following parameters: "self-confidence", "perseverance", "mood stability", "conscientiousness" and "desire to distinguish themselves". Many of these parameters correlate with IQ to one degree or another, so scientists had to make special adjustments to extract an IQ-independent component from them. Further statistical analysis showed that the combined indicator that combines data on "perseverance", "mood stability" and "conscientiousness" correlates best with life expectancy. The authors called this indicator "reliability". Due to the amendments made, the calculated indicator of "reliability" does not correlate with IQ and can be considered as an independent variable.
The previously discovered dependence of life expectancy on IQ has been fully confirmed. If we divide the entire sample studied into four parts by IQ, then representatives of the first group (the "smartest") live the longest, the second group — a little less, the third and fourth — even less, and the last two groups are indistinguishable from each other in terms of life expectancy. In other words, "completely stupid" and "just stupid" children have the same life expectancy. The scale of the differences is quite impressive. Thus, about 83% of children from groups 3 and 4 survived to the age of 65, and 92% from the first group. In other words, for children who had a high IQ score at the age of 11, the probability of not living to the age of 65 is twice as low as for children with low IQ.
The dependence of survival on intelligence assessed at the age of 11 years. IQ groups: 1 — the smartest, 4 — the stupidest. The two lower curves corresponding to groups 3 and 4 are almost identical and merge into one in the figure. Fig. from the discussed article in Psychological Science.
Similar results were obtained for "reliability", and this indicator, as it turned out, correlates with life expectancy even more strongly than IQ.
In the course of such studies, it is necessary to remember about the well-known "effect of Chinese sticks". This is a humorous example showing that correlation and causality are far from the same thing. It is known that the ability to eat with chopsticks correlates very strongly with the color and straightness of hair: owners of black straight hair use chopsticks much more dexterously than fair-haired and curly-haired citizens. This correlation has the highest level of statistical reliability. Nevertheless, it does not occur to anyone to claim that black hair contributes to the ability to eat with chopsticks.
The same is true here: the results obtained do not necessarily mean that people live a long time because they were smart or "reliable" in childhood. The reasons for the revealed correlations are not yet known for sure. To clarify the situation, the authors investigated a number of other indicators. They managed to identify 8 more indicators that, to one degree or another, allow predicting life expectancy.: 1) education (how many years a person has studied in total), 2) the combined indicator of the "quality of life in the family", 3) the occupation of the father, 4) family size, 5) crowding, 6) school attendance, 7) childhood illnesses, 8) the occupation of the subject at the age of 27. Using sophisticated statistical methods, the authors analyzed the impact of these indicators (as well as gender: it is known that women live longer) on the correlation between life expectancy, IQ and reliability. It turned out that the influence of IQ on life expectancy seems to be partly mediated: the correlation between these two indicators decreases markedly if we correct for factors No. 1, 2 and 8. "Reliability" turned out to be a more independent predictor: the correlation between reliability and life expectancy decreases only from making adjustments for education (factor 1), and then not much.
The most interesting thing is that according to the degree of influence on mortality (regardless of whether this influence is direct or indirect), IQ and "reliability" turned out to be almost as significant factors as a combination of smoking, high cholesterol and high blood pressure.
The authors point to the following possible mechanisms of the relationship between IQ and mortality:
- some genetic data suggest that developed intelligence generally positively correlates with a "good genotype", including innate resistance to diseases, etc.;
- intelligence can indirectly affect life expectancy, since people with high IQ are more likely to achieve high social and economic status and less likely to commit health-threatening acts.
As for the "reliability", the nature of the relationship of this indicator with mortality is still unclear. Guesses, of course, can be offered a lot, but psychologists do not yet have concrete facts confirming these guesses.
Source: Ian J. Deary, G. David Batty, Alison Pattie, Catharine R. Gale. More Intelligent, More Dependable Children Live Longer: A 55-Year Longitudinal Study of a Representative Sample of the Scottish Nation // Psychological Science. 2008. V. 19. P. 874-880.
Portal "Eternal youth" www.vechnayamolodost.ru23.10.2008