A few years ago, a study was conducted in Aberdeen, Scotland, which found that those who had a higher IQ as eleven-year-old schoolchildren in 1932 had a significantly higher survival rate at age 75 and older. The result was met with some harsh criticism. Didn't it discredit intelligence tests? That is certainly not the case; the results of IQ tests are generally more valid than almost any other psychological testing method. A given person's intelligence quotient remains virtually constant throughout their lifespan and is associated with crucial life consequences, such as educational achievement, professional success, disease prevalence—and, of course, mortality.

Subsequently, further studies appeared that confirmed the connection between high intelligence and long life expectancy. One of these included nearly one million Swedish men who were tested at around 19 and then observed for almost 20 years. This study also produced a clear result: As IQ increased, so did the probability of survival during this 20-year period.

Intelligence quotient predicts lifespan

The IQ can predict a person's mortality probability better than their body mass index (BMI), cholesterol, blood sugar, or blood pressure levels, and about as well as their cigarette consumption. But the reason for this remains mysterious. This cannot remain so, because society should be concerned with correcting imbalances in the healthcare system. But to do this, we must understand the cause of the imbalance.

Four factors could play a role

In general, four explanations are given for the phenomenon described, but these do not necessarily exclude each other:

First, higher intelligence correlates with higher education, which in turn correlates with jobs performed in healthy environments. People with higher education move into higher social classes with better medical care.

Second, people with higher intelligence behave healthier. Studies show that people with higher IQs eat healthier overall, exercise more, engage in less risky behavior, smoke and drink less alcohol, and gain less weight as they age. All factors that contribute to life expectancy.

Third, brain damage may have already occurred before the IQ tests were administered in adolescence, for example, damage during birth or later due to illness, accidents, or developmental disorders. This could explain both the lower IQ and the higher mortality.

Fourth, high IQ scores in youth may indicate overall good physical condition. Such a well-equipped body could better cope with environmental stresses throughout life, which would have a positive impact on mortality.

Reliability and a sense of duty also play a role

Whether one or more of these hypotheses are correct remains unclear and is the subject of further research. Among other things, it has been found that intelligence alone does not predict mortality. Children who score above average in reliability and conscientiousness are twice as likely to live beyond 65 as those with below-average scores in these areas.

Even though the influence of intelligence on mortality has been proven, this doesn't necessarily have to be predetermined. Intelligence doesn't spin, measure, and cut the thread of our lives in a fateful way. The factors that allow more intelligent people to live longer simply need to be identified, and then perhaps this knowledge can be used for the benefit of all.