Is it true that scores on IQ tests are positively correlated with greater lifespan? If so, why is this the case?
Does this finding still hold once you adjust for obesity, which is known to be both negatively correlated with IQ and positively associated with increased mortality? Does it hold if you adjust for smoking and mortality risk due to occupational hazards?
For one thing . . . in countries without universal healthcare, people with high IQs are more likely to have health insurance, and so have greater access to doctors, medications, etc. Also, people with better-paying jobs can afford to eat healthier, if they choose to. There might also be sociological factors, like less exposure to violence in general. And white-collar jobs tend to have fewer physical risks than blue-collar jobs.
There have been studies that link alzheimer’s with average or lower IQs. We only tend to hear about the mental effects of the disease, but as the disease progresses many of the symptoms are physically debilitating too.
IQ tests have a strong cultural bias, and generally privilege people with a formal education. If you have a formal education, you’re more likely to have access to health-care.
Two other reasons come to my mind. First; smarter people are more likely to take intellectually difficult work, which tends to be less dangerous.
And second, I’d expect higher intelligence to have a small but detectable correlation with general physical health. Physical beauty does have such a correlation; despite the stereotype, good looking people are on average just a bit smarter. As I understand it, this is thought to be because good looking people tend to have fewer defective or substandard genes ( specifially, those defective genes which affect appearance ), some of which can affect the mind as well as the body. The same principle should apply the other way around; smart people are going to have fewer defects than average ( since some defects lower intelligence ), and so they should have a slightly longer natural lifespan.
Not only that, but physical health, physical beauty and intelligence are all affected by childhood nutrition. So if you have someone who was malnourished enough for it to affect their intellect, it probably also isn’t helping their health.
I’m curious–do you have any links with relevant info? I for one first took the test as a 1st grader, before any formal education and in an unfamiliar language. More recent tests haven’t made a difference, and there’s even been a slight drop.
So people’s IQs change as they gain or lose weight? If I’m in one country where large women are given a higher value (Italy or Spain) and I am thin, will my IQ go up when I go to America where the standard for beauty is skinnier? What if really tall women are valued and I am only 5’9"? Does that make me dumber than the 6’4" beauty? If my brother has only four years at Oxford is his IQ lower than my sister who spent six years at Cowabunga State? What if the only reason I smoked was because I wanted to run through a meadow and meet a man?
Probably not, since those are all variable physical qualities. Simple weight change isn’t going to change your intelligence as an adult. Unless you take it to extremes perhaps.
Statistically, good looking, tall people are going to be smarter, since on average those qualities result from having fewer genetic defects and better nutrition. That doesn’t necessarily mean you are though.
Since smoking is a foolish act, I’d expect smokers to be on average less intelligent.
Which is why I said “on average”. I’d expect smart people to avoid starting smoking more than stupid people ( once they start, intelligence won’t do them any good ). Just as I’d expect smart people on average to be more likely to avoid doing stupid things in general.
IQ scores are also correlated with things like childhood nutrition and exposure to stress (kids who grow up in war zones or abusive environments have lower IQ scores). It also happens that lack of nutrition and high stress will shorten a person’s life significantly.
So really lower IQ individuals do make dumber choices than higher IQ individuals do - in health habits like smoking or not quitting and whether or not they exercise, perhaps in who they hang out with and in how they deal with conflict, and in how they otherwise manage their personal safety.