How do you sink a submarine full of blondes?Knock on the door.It took me a moment to work this one out when I read it today, but that was because I hadn't had enough coffee yet, not because of my hair color. Duh. I've been on the receiving end of my share of dumb blonde jokes. But everyone knows they're based on a false stereotype, right? (Everyone except for my high school physics teacher, who told me after class one day that I had turned out to be smarter than I looked.) Research scientist Jay L. Zagorsky , PhD — who, for the record, has brown hair — recently took it upon himself to supply hard evidence debunking the myth of the dumb blonde.He used data from the NLSY79 , a nationally representative survey of 12,686 men and women who were 14 to 22 years old when they were first surveyed in 1979, and are now interviewed every other year, to analyze the IQ of women and men by hair color. It's worth noting that this research isn't peer-reviewed and that it looks only at white men and women; what's more, the ability of IQ tests to truly measure intelligence has been called into question . (Some researchers say that IQ scores have historically given people ammunition to link inherent cognitive ability to race, gender, and class, which is not cool.)That said, blondes everywhere can take heart that Dr. Zagorsky's research project found no evidence that blondes as a group have lower IQ scores than groups of people with other hair colors. In fact, in the sample he analyzed, blonde women had a slightly higher average IQ than women with brown, red, or black hair; they were also less likely to have an extremely low IQ. It's a leap to say that this result would hold true across the general population, but if you've seen my old physics teacher lately, would you tell him about this anyway? Maybe he'd respect an old brunette guy's opinion more than mine.