All jokes aside, the average IQ of blondes was actually slightly higher than all other hair colors.
The stereotypical dumb valley girl in popular movies is usually blonde, and there’s certainly no shortage of “dumb blonde” jokes.
However, according to a new national study of young baby boomers, scientists say that the “dumb blonde” stereotype is simply wrong.
The study looked at 10,878 Americans of all hair colors, using data from the National Longitudinal Survey of Youth which first interviewed people ages 14 to 21 in 1979. Then, the participants took the Armed Forces Qualification Test (AFQT), which is used by the Pentagon to determine the intelligence of recruits. The AFQT scores is based on paragraph comprehension, word knowledge, math knowledge, and arithmetic reasoning.
To eliminate any bias caused by ethnic and racial differences, the researchers dropped the IQ test results of all African Americans and Hispanics from the analysis.
The results, published in the journal Economics Bulletin, revealed that blonde white women had an average IQ of 103.2, compared to 102.7 for brunettes, 101.2 for redheads, and 100.5 for women with black hair.
Although the study found that, on average, the IQ of blondes was actually slightly higher than those with different hair colors, it’s not enough to be statistically significant, according to study author Jay Zagorsky, a research scientist at Ohio State University.
"I don't think you can say with certainty that blondes are smarter than others, but you can definitely say they are not any dumber,” he said in a press statement.
The results were similar for men as well — blonde men had IQs roughly equal to men with other hair colors.
The study can’t say for sure whether these findings were based on any genetic relationships between hair color and intelligence, but Zagorsky mentioned one possibility that could explain why blondes showed a bit of a higher intelligence: "If blondes have any slight advantage, it may simply be that they were more likely to grow up in homes with more intellectual stimulation," he said.
In short, blondes may be more likely to grow up in home environments with more reading materials than those with other hair colors, says Zagorsky.
Although the whole dumb blonde stereotype may seem laughable (if you aren’t blonde, that is), it actually might be more damaging than it seems at surface value.
"Research shows that stereotypes often have an impact on hiring, promotions and other social experiences," Zagorsky said.
"This study provides compelling evidence that there shouldn't be any discrimination against blondes based on their intelligence."
Who knows, maybe researchers will look into the famous, time-old claim next — do blondes really have more fun?