[VonDondu]

I don't know much about genetics, but in my experience, the gene for red hair is very robust. My paternal grandmother had red hair, and even though my father doesn't have red hair (he had blond hair when he was kid but it changed to dark brown--almost brunette--when he got older, like his father), you can see the effect of the red gene in my hair: the dark brown hair on my head has a light red sheen, and there are individual red hairs scattered on my arms and legs which are almost invisible among the darker hairs. My brother has hair like my father and my paternal grandfather (blond when he was a kid and then dark brown later in life). His wife is Chinese, and her hair is a little bit lighter and finer than usual (it's not as thick and dark as the rest of her family's, so maybe she has a recessive gene). Their daughter (my niece) has hair that is best described as "reddish brown". It's definitely in the medium brown category, but there's even more red in it than there is in mine. My nephew has light brown hair, but it's not reddish (maybe it will get darker when he's older). It just goes to show that genes for hair color don't follow the stereotypical patterns most people take for granted. Blond/brunette/red is a pretty artificial distinction.

I'm not surprised that people lack the imagination to envision prehistoric people with some other hair color besides black. I'd be a lot more surprised if prehistoric people did NOT have a big variety of hair colors. Heck, they probably even paid attention to cosmetics and fashion just like we do (within their own means, of course).

My brother and his family live in a community that has a lot of "diversity", and mixed-race couples are not unusual. In my own community, I guess there's a lot of what you might call "social segregation"--not literal segregation, but not much socializing between the various races. I don't know which type of community is the "norm" in human history, but human genes certainly don't care about such boundaries, and they're likely to pop up in all sorts of combinations. There's just no such thing as racial/genetic purity, no matter what sort of artificial distinctions people try to impose on themselves.