Most people who have more than one child—or at least one sibling—have thought about the effects that birth order have on people. Older kids are supposedly more compliant and want to please, middle kids are the great negotiators, and so on. There’s almost always a grain of truth in every stereotype, but what about hair color? Do blondes really have more fun? Do redheads really have more fiery personalities? Two fascinating studies may shed some light on both of these questions.
In the first, researchers looked at whether hair color could affect the results of hair tests for illegal drugs. Urine tests are routinely used for that purpose, but thousands of people every year have hair tests. First, they’re less invasive. Second, while traces of drugs aren’t detectable in urine after just a few days, they stay in the hair until it gets cut off or falls out. So Douglas E. Rollins from the University of Utah and his team collected hair samples from 24 men and 20 women with black, blond, brown, or red hair. They then gave the subjects about a tablespoon of codeine syrup three times a day for five days. After that, they collected hair 1, 4, 5, 6, and 7 weeks after the last dose of codeine.
Using the federal guidelines for what constitutes a positive test result (200 picograms per milligram–pc/mg), the results showed some pretty stark differences between hair colors. Even though all of the subjects took the exact same amount of codeine, 100% of those with black hair and 50% of those with brown hair would have been flagged as positive. But tests on blonds or redheads would have come back negative. So whether blonds really have more fun is still debatable; but we we know that they can certainly have more illegal-drug-related fun without anyone finding out about it. You can see the full report here.
Now, on to redheads and their supposedly spunky personality. On average, women are more sensitive to pain than men and require more pain killing medication than men. But researcher Edwin B. Liem and his team from the University of Louisville wanted to see whether hair color would make a difference in terms of pain sensitivity and responsiveness to pain meds.
To do that, they subjected 30 red-haired and 30 dark-haired women to a variety of unpleasant experiments (all of the women were volunteers who knew what they were in for), including maximum pain tolerance to electrical current, heat, and cold. They then tested the women’s response to the pain medication lidocaine.
Liem and his team found that while redheads and dark-haired women were equally sensitive to electrical current, the redheads were more sensitive to cold- and heat pain and were less able to tolerate extreme temperatures on either end of the scale. The redheads were also significantly more resistant to lidocaine (in other words, it wasn’t as effective in dulling the pain as it was for dark-haired women. So do redheads have more fiery personalities? Could be. And if so, it might be because they’re in more pain than other women. You can read the study here.