Did you hear the legend that blonds will die out in just a couple hundred years? I did. It turns out that everyone has — because the legend has been around for a couple hundred years. Here's why blonds have spent centuries on the endangered species list.
I was in high school when I first heard that blonds were going extinct. The hair color was the result of a recessive gene. Over the next couple hundred years, dominant genes will overcome the recessive allele for blond hair and there will no longer be natural blonds on Earth. I've never been the type of brunette to resent blonds, so the idea made me vaguely sad — a bit of visual difference dying out.
It's been making people sad for a long time. The legend of the disappearing blonds has been around since 1865, and it was an old story even back then. A Parisian fashion magazine had noted that for the past few years dark eyes and dark hair were in fashion, but blue eyes and blonde hair (in women, at least) was back in. The article discussed certain "wise men" claiming that blonds would go extinct, and mocked "Darwinian doctrinaires" who didn't know what they were talking about.
It seems that the long-standing rumor was never true. Genes do not work that way. Although the recessive alleles of genes won't always show when paired with dominant genes, they aren't "overcome." They are not eliminated. In fact they are passed down through successive generations just as readily as any other genes, and will continue popping up in any population. Unless the "blond" genes are selected against sexually (not likely), or have cause some grave disadvantage (not that we've noticed), they won't be eliminated. If a huge amount of blond people get themselves dark haired spouses, their genes might not directly show up in their children's hair. But those children will intermarry, and the recessive genes will get paired up in the next generation. In fact, if blonds do a good amount of baby-making, the absolute number of blond genes in the world will increase.
It should be common sense that blonds aren't dying out. Blond genes and dark genes have been mixing for thousands of years in Europe, and in places like the Solomon Islands, and haven't died out. And yet it's a meme that just keeps popping up.