Scholars used to avidly study human intelligence. They measured cranial capacity. They administered IQ tests. They sought to define what intelligence was and who had more or less of it and why.
These days, not so much. Somewhere along the way, the very idea of intelligence became politicized. Its legitimacy as a field of study, as a measurable quality -- on par with height, eyesight and hand-and-eye coordination -- and as a concept came under fire. Talk of "brainpower" and "smarts" ebbed as scholars proposed "multiple intelligences" -- such as musical, spatial, interpersonal and intrapersonal -- rather than whatever had hitherto been called IQ. An IQ blackout has descended. When researchers talk about IQ at all, the big question is whether it's inherited, and if so, how much. IQ now faces fierce competition from SQ and EQ, social and emotional intelligence, two burgeoning theories.
Why are our minds and their capabilities among the most taboo topics in 21st-century academia?
"I believe there are a number of factors involved," says Dennis Garlick, a postdoctoral researcher in psychology at UCLA and the author of Intelligence and the Brain: Solving the Mystery of Why People Differ in IQ and How a Child Can Be a Genius (Aesop, 2010). "Certainly a major factor is the race issue. Arguing that the races differ in IQ has tainted the whole field, and many researchers and commentators would prefer to just avoid the area for fear of being labeled racists."
Much of that taint and fear dates back to the work of UC Berkeley psychologist Arthur Jensen, whose writings in the 1960s linking differences in cognitive ability with differences in race sparked protests on the Berkeley campus and outrage in the scientific community that echoes to this day.
"The most important fact about intelligence is that we can measure it," Jensen wrote in his most famous work, "How Much Can We Boost IQ and Scholastic Achievement?" published in the Harvard Educational Review in 1969.
"IQ is known to predict scholastic performance better than any other single measurable attribute of the child," Jensen wrote.
Asserting that intelligence is "heritable" -- that it's mainly in our genes -- he then warned against making racial generalizations: against, in a sense, being racist.
"Whenever we select a person for some special educational purpose ... we are selecting an individual, and we are selecting him and dealing with him for reasons of his individuality. ... Since, as far as we know, the full range of human talents is represented in all the major races of man and in all socioeconomic levels, it is unjust to allow the mere fact of an individual's racial or social background to affect the treatment accorded to him."
Jensen then went on to advocate diversity, although not quite in the same way we do today.
"Schools and society must provide a range and diversity of educational methods, programs, and goals," Jensen demanded: In other words, diversify the curricula, not necessarily the faculty or student body.
"Jensen is still greatly respected by many traditional intelligence researchers," Garlick says. "By 'traditional intelligence researchers,' I mean researchers who still value IQ and continue to do studies that evaluate the effectiveness of IQ in predicting outcomes, or studies that examine possible mechanisms that may cause differences in IQ. However, due to the unpopularity of Jensen’s findings, this group of researchers is now very small.
"The major move in response to Jensen’s findings hasn’t been rigorous and compelling research to try and disprove his hypotheses and findings. Rather, it has led to an exodus of researchers away from the area, and a drying up of grant funding and research positions for researchers interested in IQ."
Jensen's work was a flashpoint dividing the study of human intelligence into two periods: BJ and AJ, you might say.
"The post-Jensen period has not been filled with good research aimed at disproving and discounting Jensen’s hypotheses," Garlick laments, "but rather with treating not just Jensen but the field of IQ in general as persona non grata. What this means for people who are low in intelligence is very much up to debate."
IQ is un-PC, Garlick adds, because "studying IQ is highlighting differences between people. Identifying differences between people in a characteristic where one end of the spectrum is associated with many more negative outcomes can result in hurtful information."
Throughout history, this "hurtful information" has meant the exclusion of those who score low on IQ tests from schools, careers and clubs.
For many, it has also meant the difference between life and death. IQ-test results have been used to justify some of humanity's worst crimes.
"If you believe that IQ measures something genetic, scientifically and precisely measurable, and of paramount importance in life, then it's easy to believe that people who score very low should not be allowed to have children," says human-rights lawyer turned journalist Stephen Murdoch, author of IQ: A Smart History of a Failed Idea (Wiley, 2007). "In America before WWII, more than 60,0000 low scorers were coercively sexually sterilized. In Europe -- especially Germany, of course -- hundreds of thousands were, as well. ... The Nazis went so far as to execute untold thousands of low IQ scorers."
IQ tests had long been ubiquitous by then.
"IQ tests took off a century ago because many institutions, in America in particular, had an overwhelming number of people to make decisions about," Murdoch explains. "IQ tests, or at least some sorting tool, became necessary as America and other western countries industrialized and modernized. When universal education laws were passed and schools became crowded schools needed a way to determine who went into gifted, average and remedial classes. Doctors on Ellis Island needed a scientific way of sending people back to Europe. When the US Army had to screen and process millions of men to fight in Europe during the first World War, they needed to do so efficiently in large groups.
"IQ tests were born of historical necessity and happenstance, not intelligence theory or science."
Some would argue this point.
"While IQ tests are not a perfect measure of intelligence -- and a perfect measure does not exist -- performance on an IQ test can provide important insight into a person’s relative ability to understand concepts that play a role in successful performance in both educational and work domains," Garlick says.
"The major problem with ignoring differences in intelligence is that this does not resolve the underlying issue. For instance, low IQ can be reflected in poor performance at school. To address this, the criteria for 'successful' performance at school can be lowered. Children will then get higher grades. But simply telling children that they are doing well in their schoolwork when they have not mastered the underlying concepts will not help them later on when they are expected to apply their school learning to other situations.
"I find it ironical that so much research is devoted to disorders like autism that only affect less than 1 percent of the population, but little research is devoted to understanding differences in IQ. ... If the deficits of autism can be improved through research, why not IQ?"
Today's intelligence wars rage around the intersections between science, ethics and politics.
"The science underlying IQ tests isn't like experiments in the life or hard sciences," Murdoch insists. "IQ proponents believe in something they call general intelligence. That is, they believe there is one singular, measurable, inheritable kind of intelligence that we can all be ranked on. I have no idea if this is correct or not. Nor do I care.
"Other traits, such as conscientiousness or self-control, might be viewed as equally or more important. ... As long as there is disagreement in the field about what intelligence is, we should remain agnostic and ignore what the intelligence experts say the nature of intelligence is. ... We listened to the intelligence experts in the 20th century with dire consequences," Murdoch says.
"Unfortunately, there are researchers who are still interested in the differences between races. I have no idea why. What's the intellectual appeal or social utility of such studies? It escapes me. ... I believe in academic freedom: Let them study the issue if they want to. Just ignore them."
Coming two decades after the Nazis used IQ to justify slaughter, Jensen's research documenting IQ differences between (among other things) ethnic groups filled scholars with such fear about how this research might be used that many folded their notes and left the field. Others turned to alternatives such as SQ and EQ.
"There is still little evidence to support many of the claims made by proponents of alternative intelligences," Garlick says, "yet it is advocated that life-changing decisions should be made based upon them. One is tempted to say that the alternative intelligence industry is a reminder that snake-oil salesmen are alive and well in this day and age."