That original article can be found here;
Normally, when there's only limited human travel (as there would've been in earlier times) this spectrum remains pretty steady and boring. As people tend to settle down and have children with people near to where they themselves are on this spectrum. However, once long distance travel begins, particularly sea travel, then you start getting people who look very different from each other intermarrying. Resulting in more chaotic, random colouring of the offspring. Hence red hair, freckles and hazel eyes.
To illustrate things a little better I'll split the world into regions;
(click to enlarge)
More often than not, due to limitations of travel, someone from Region A would only have offspring with someone from Region A or Region B. Meaning the offspring would be blond, light-skinned and blue-eyed, or perhaps ever so slightly darker than that (i.e. slightly further down the scale). The same with all the other regions, who only interact with the regions next door to themselves.
However, once you have Region A people meeting Region E people then all hell breaks loose, and strange variations pop up due to the sheer range of genes the offspring may inherit. Now sure, 9 out of 10 offspring may look something like Region C people, but 1 in 10 may have the luminosity of blond hair, but mixed with a darker tone not normally seen in standard blondes (red hair). Or eyes that are some strange mixture of bright blue and dark brown (hazel eyes). And so on and so forth.
Anyway, with that little description out the way I'll move on to the few things I wanted to add to the original article.
The Russia and Ireland Trade Route Melting Pots
(A red hair map, showing its
approximate frequency across Europe)
The above map shows the classic and familiar distribution of redheads across Europe. With the highest proportion generally appearing in Ireland and Scotland. There's also that little red dot in Russia, which has always been something of a fascination to me and others interested in this topic.
This theory that red hair is the product of diverse peoples mixing fits this map quite nicely.
Ireland and Scotland are perfectly positioned on the western coast of Europe, between the Mediterranean and Scandinavia. Meaning that thanks to sea travel up and down the Atlantic coast Irish and Scots may have a greater proportion of ancestors from these very different regions. A very large melting pot so to speak.
Likewise with Russia. Where trade routes would've stretched between the Middle East and Scandinavia via both land and inland sea routes. Namely around the Caspian and Black Seas.
So you could speculate that these little melting pots of trade and travel produced heightened numbers of redheads.
The Pale Skin Illusion
Another thing I want to mention in this article is the supposed unique paleness of redheads. The general opinion is that red-haired people are much more pale than other white people. Even more so than blonds. In fact, the skin is often described as translucent by observers.
However, I would proffer that redheads are no more pale than other white people and that this perceived extra paleness is simply an illusion. Created by the contrast of the red hair and freckles against the whiteness of the skin. For example, my freckly skin tans. However, the tanned skin still looks very white sat next to the much darker brown freckles. So it's like an optical effect.
I would speculate that in general redheads are no more pale than the average blond person.
Something which increases my confidence in this statement is a discussion I had with my friend. I brought up this little theory and he was adamantly against it.
"No, red-haired people are much paler, it's obvious! You can tell just from looking!"The phrase "ginger skin" was even used, which in turn then led to a discussion about red-haired celebrities. The question being could you still tell that a person was ginger if they dyed their hair blond and you'd only ever known them as that colour. Sneakily I threw a few people into the conversation that were famous for being redheads, but that were in actual fact non-redheads - Tori Amos, Christina Hendricks, Florence Welch, to name a few. (Finally all that knowledge I'd acquired about red hair had a use).
Anyway, he was insistent that all these people, including the unbeknownst to him non-redheads, were so "ginger looking" that even with hair of another colour their overwhelming gingerness would shine forth. So he was quite disbelieving when I pointed out that some weren't even redheads to begin with.
Of course, this is just anecdotal evidence, but it does lend weight to the notion that the skin tone of red-haired people isn't especially different, and that any reasonably pale person can "look" ginger with the addition of red hair or freckles.
A final thing I'd like to mention - and again, this is total speculation here ..but interesting speculation nonetheless - is the perceived association between red hair and sexual licentiousness. This is largely no doubt a product of the vividness of the red colouring - as with sexually alluring red lips for example. However, could this historic and seemingly ingrained association also be a product of the observation that red hair is a product of race mixing?
Something that would be seen as taboo in otherwise homogeneous tribal groups.
If red hair popped up in melting pot societies then this visible otherness could be perceived as an indicator of mixing with outsiders. So perhaps it would've been viewed as evidence that people had had sex beyond their immediate tribal groupings. Viewed through this lens of racial homogeneity it would be seen as an impurity, which of course is how freckles and red hair are often viewed today.
And I'll leave it there for now :)