Can all blue-eyed genes be traced to a European lineage? Can all curly or frizzy hair be traced to a traditionally Black origin? I realize that concepts of race are rapidly changing, so I’m not even sure that my question makes sense in the light of current knowledge.
Pardon me for bumping my own thread. I was really hoping someone might know.
Well, we all came out of Africa within the last 60-70k years, so perhaps it’s more accurate to say that all genes have a “Black” origin.
Looking at phenotypes, it’s pretty clear that curly/frizzy hair is seen in populations long out of Africa-- eg, those in New Guinea. I’m unaware of any significant population of blue eyed people that are not traditionally from Europe, although it would be more accurate to say that the incidence of blue eyes in individuals declines significantly as one moves from Europe into Asia.
There were reports of a significant population of light haired/blue eyed Amerinds among the Mandan tribes, but it was unclear if that was due to interbreeding with Europeans or if it was a local varient, or if it was ever actually true in the first place.
Of course, no one has isloated the eye color genes or the the hair texture genes, so it’s pretty much a guess. I don’t even know if there is consensus among geneticists one exactly how many genes are involved in those two traits.
Generally light colored irises are the result of pigments that are also present in dark irises. Therefore, loss of a functional gene for a nonessential darker pigment reveals the lighter color underneath. This would be expected to have happened many many times in tens or hundreds of thousands of years, in a population the size of Earth’s.
Though such defective or inactive genes would be present in the gene pool, they would usually be covered up by the presence of a dark-color gene on the other chromosome (heterozygosity). Some uncommon individuals would get two light color genes by ‘the luck of the draw’.
However, in relatively small groups (available mate choice was relatively small for most people in most of human history), uncommon single genes (allelles) can come to predominate in the local gene pool. This is called ‘allellic drift’. Usually the opposite occurs -the rarer gene is lost- unless there is some selective pressure (such as light eyes being a mating advantage for personal or cultural reasons). Selective cultural pressures can produce neighboring populations with distinct characteristics (e.g. tall tribes living near short tribes) which can be used to further enforce genetic isolation (e.g. deter interbreeding)
Uncommon genes can also become fixed in a small population by the founder effect (if all or most of the founders of a breakaway group or isolated population possess the uncommon gene) Allelic Drift and founder effects have been studied for eye color and other traits in small or isolated populations, such as Pitcairn Island or African tribes
Almost certainly not. The first records of blue eyes I’m aware of come from writing and painting out of Egypt, which is of course Africa. Naturally there were plenty of people of blue-eyed people in Europe at the time, but the presence of blue eyes suggests that the genotype can survive quite well in the Mediterranean/North Africa region. Certainly there are no shortage of blue eyed Italians. Blue eyes are recessive, and so the gene almost certainly originated in Africa and was selected against in the tropics. It seems fairly plausible that it became widely expressed once people moved into Asia Minor and North Africa since blue eyes have been fairly widepsread there for millenia.
Probably not. Curly hair is almost certainly the primitive condition in humans. Whether the first humans were black is still open to debate, but current opinion seems to be that they weren’t. The first humans were probably brown. If that’s the case then curly hair is can be traced to a brown origin and was later inhertited by black people as well as others.