Smarts matter in our high-tech age of standardized tests, iPhone entrepreneurs and nanotech venture capitalists. "The future is built on brains, not prom court, as most people can tell you after attending their high school reunion," as the writer Anna Quindlen, puts it.
But how smart are we about smarts? Not too smart, suggests some looks at the science behind intelligence and achievement.
"Family income is a strong and consistent predictor," of test scores, school grades and education, say a Cornell University study in the current Proceedings of the National Academy of Sciences journal. "The longer the childhood exposure to poverty, the worse the achievement levels become."
Although a "large, robust literature" stretching back more than a decade describes this observation, study authors Gary Evans and Michelle Schamberg note there is no biological explanation for it. Why does poverty have this effect?
To find an answer, the pair looked at 195 men who were part of a long-term study of rural poverty. The study included health records and income. In 2006, about 22% of all children nationwide lived below the poverty line, living on less than $21,200 for a family of four, according to the federal Department of Health and Human Services. (About 18% of people worldwide live below the international poverty line of $1 a day, according to Princeton economist Alan Krueger.)
At age 17, all of the men in the study had their " working memory," the short-term ability to remember things briefly, assessed. Intelligence tests and grades more typically test longer-term memories, measuring knowledge.
"The proportion of early childhood spent in poverty is also significantly related to working memory," finds the study, perhaps not surprising. But when the researchers went back and looked at the men's health records, the relationship between poverty and memory dissolved, revealing their health — as reflected in blood pressure, obesity and stress hormone measures — is the real factor. What looks like an income effect is actually a public health problem.
Stress hormones over time are widely known to interfere with memory, an effect described in neuroscientist Robert Sapolsky's popular science book, Why Zebra's Don't Get Ulcers. Chronic stress alters brain chemistry, damaging a part of the brain called the hippocampus, central to memory formation. Although the study can't go back in time to look inside the brains of the young men in the study, the researchers suggest something similar likely occurred to them.
Brain chemistry aside, simply assessing intelligence remains a controversial topic, particularly widely-used "intelligence quotient" or IQ tests. The so-called " Flynn Effect," the 1994 observation by New Zealand researcher James Flynn that IQ scores have risen from generation to generation for every country ever studied, with the gains coming not from vocabulary, math or other school topics, but in abstract thinking.
Some researchers, such as Richard Lynn of the University of Ulster, suggest the tests are worthwhile, however, pointing to improved nutrition among the poor in societies as driving the IQ increases.
"The 20th Century has seen both massive height gains and massive IQ gains," Flynn himself notes in a study in the current Economics & Human Biology journal, an argument for the nutrition explanation for IQ gains. But looking at diet and IQ scores in the United Kingdom from 1938 to 2008, he suggests, knocks the legs out from under that explanation.
In the study, Flynn looked at schoolchildren measured in 1938, 1947, 1982 and 2008, showing 11-year-olds in that time averaged a 15.6 IQ-point-gain during that 70-year period. The biggest jump took place between 1938 and 1947. However the gains were much more pronounced among wealthier kids than poorer ones, "which would imply that the upper classes made larger dietary gains than the lower classes as we go into the more distant past," Flynn writes, which he finds unlikely.
Instead he argues, "During the 20th Century, society evolved and therefore, set new cognitive problems that made us think differently than we did at its beginning." The modern world demands its inhabitants deal with abstractions, so we do better with abstract test questions now, Flynn argues, rather than being any smarter.
Doubtless, debate over the roots of intelligence will continue. After all, "Ideas are like pizza dough, made to be tossed around," as Quindlen also once wrote.
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