On second thought it is possible that my ancestors came from some area that is now China. Those fair-skinned red-headed people of the eastern steppes are thought to have migrated to north western Europe I believe and they may have spawned my Scottish ancestors. muawiyah would be the one to ask about that.
This seems to be related to latitude, and allows more light to penetrate into your body so you can produce more Vitamin D. That allows you to settle even further North.
Red Hair was developed two times that we know of ~ with entirely different genes doing the job. It, too, is probably related to long term climate ~ an area not only in the North, but also with lots of fog! Think of it as 'super light'. A recent discussion I read about it said everybody continues to produce melanin. They do that even if they have these light skin genes. The light skin genes do several things ~ they suppress melanin production, but not entirely, since you need the stuff for other things as well. The European version also converts some of it to a RED/YELLOW chemical in a minority of Europeans (the sacred 300,000,000 red heads).
As these same people age they lose some of the capacity to totally suppress melanin and it will start showing up in their hair ~ which is why you have naturally red and strawberry blond people grow old and develop darker hair. In younger people that process can also be seen as FRECKLES.
Then there are people who naturally produce multi-colored hair ~ which is indicative of competing melanin suppression systems irregularly distributed in your body's cells.
Old timers here remember my complaint about cataract surgery depriving me of my naturally bright green eyes with their golden center. Well, they're back. The bad blue eyes began to produce melanin, and the anti-melanin genes began breaking it down. What that means is most of my eye color was located in two layers ~ the top of my lens and the inside of my cornea ~ so when the lens pocket was vacuumed by the eye surgeon it was all sucked out. Now, as i'm getting older, and producing less and less anti-melanin chemicals, the melanin has been able to use a single surface ~ the inside of my cornea ~ to build back some natural flashing green color.
The European people with the most intense melanin production system, and the red hair gene, are demonstrably derived from the Western European Ice Age Refugia population ~ and they lived in Northern Spain/Southern France in an unglaciated region.
They are the primary source of red hair in this world. They began moving out of the area toward the end of the ice age but before its peak about 24,000 years ago ~ and made it to North Africa, Scandinavia, Africa and North America. They appear to have stopped moving to North America (across the Atlantic ice bridge) by the peak of 20,000 years ago. Then, when the ice began the big meltdown they moved North in Europe to Scandinavia as fast as the ice melted. Light skin and blond hair may have shown up in European derived populations with that particular movement. The ability to drink cows milk as an adult didn't develop universally at that time, which is definitely in line with the thinking that the far north Scandinavian population experienced an extended isolation from the more Southerly populations for several thousandyears ~ an inability to digest milk sugar continues on in the far north even today ~
The answer to the question ~ where did you get Red Headed Chinese ~ is currently addressed by noting that these people's DNA also shows genes typical of East Asians. They are mixed. Some had pronounced European features and others pronounced East Asian features, but they were also mixed culturally, so you find those tartans on some of those East Asian looking mummies as well.
These folks arrived together in that part of the world about 5,000 to 6,000 years ago. The red heads necessarily came from the Far West and North ~ where red heads are still numerous. Many archaeologists are prepared now to say these people are ancestral to the Tocharians ~ who spoke a sort of Gaellic.
We know the Gaellic speaking peoples had a major settlement area in Central/Eastern Anatolia ~still, notice that jump I just made from 18000 years ago to 5000 years ago ~ just moving your camp a couple of times a year could, over that period, enable your tribe to go almost everywhere in Eurasia!
Peeps moved away ~ they came back ~ they went North, they went South, the Sa'ami seem to be genetically ancestral to the first Paleolithic populations in North America, North Africa, parts of West Africa, and various spots in Eastern Europe. They are even ancestral to the Yakuts-Sakha. Before the age of DNA analysis there were those who imagined the Sa'ami came from the far east ~ but lo and behold, they are Western European in origin. At the same time East Asians have a 5% European ancestry, and Europeans, in general, have a 5% East Asian origin.
That's probably from nothing more than random genetic spread that occurs when you tribes trade their daughters to other neighboring tribes, and that, of course, is what human beings do to maintain genetic diversity. Those who don't just kinda' die off and disappear, so we don't know anything about those guys.