In 1916, Stanford psychologist Lewis Terman created a standardized test to "rapidly and quantitatively assess general intelligence." If the subject's mental age was the same as their physical age, they were given a score of 100. Should that subject be less mentally intelligent than their age, the score dropped below 100, and would rise above 100 for those who were mentally smarter than their given age. This numerical measure of intelligence was well-suited to the demands of the First and Second World Wars because the recruits had to be assigned a variety of wartime tasks which required diverse skillsets. The IQ test gave the military the "perfect" way to determine who got assigned which tasks. After these wars, when the recruits re-entered civilian life, IQ tests were becoming very common in the workforce.
Rightly or wrongly labels, categories, and measurements help us navigate the world we live in. As a shortcut to determining someone's IQ, the tests became a huge fad during the 1940's and '50's. It was even common practice to list your IQ on your job resume!
Fortunately, today, we're a little smarter when it comes to evaluating the worth of IQ tests. While they do still serve a function, these tests don't look at the "bigger picture." There are aspects of intelligence, that the standarized IQ test doesn't look at; things that weren't even considered back at the turn of the 20th century. Every year, we learn so much more about the brain and how it works. Scientists of today speculate that general intelligence, the "g," can be partly inherited and influenced by many different genes; and environment can strongly modify it. To some degree, then, intelligence is part nature and part nurture. Research shows that some combination of genes and environment can greatly affect our intelligence, but that this combination will rarely be passed, intact, from parent to child.
Yet with all these different factors, humans still search for a way to measure intelligence. During the 1980's studies were performed that showed white children scored higher in IQ than their black peers. This added fuel to fire for racists, of course, but science decided to question the validity of their own tests. Their conclusion was that IQ tests can't actuately measure a human's general intelligence, that mythical "g," without looking at external factors such as poverty, illness, and educational opportunities. Otherwise, it's a bit like comparing apples to oranges. Yes, they're both fruit but that's about as far as the similarities go.
Personally, I believe that IQ tests can do more harm than good. A person's IQ test scores often adversely hang over them for the rest of their lives; "I can't do this, or that; I'm not smart enough and I have the test score to prove it." Throughout the centuries, though, mankind has shown that hard work and gumption can co along away towards making anyone successful in life; that it isn't simply a case of being born smart. One of the nicest things we can do for others, as well as for ourselves, is to stop judging intelligence.
I've known a few folks who were "dumb as a box a rocks"...at least by IQ test standards (with scores way below that magic 100 mark) who have gone on to become highly respected in their professions. Here a few examples that may surprise you: Mohammed Ali had a score of 78; Ronald Regan had a score of 105...barely over "average" and nearly the same score as Britney Spears (104); and Andy Warhol's score was 86.
You see what I mean? It's not all about the number. Let's learn to stop judging people by quantitative measures. But, rather, by their own individual merits.