From the source, “
To begin, please point your elbow to the ceiling.
Then imagine yourself naked.
Different Place, Different Color
Skin has changed color in human lineages much faster than scientists had previously supposed, even without intermarriage, Jablonski says. Recent developments in comparative genomics allow scientists to sample the DNA in modern humans…
By creating genetic “clocks,” scientists can make fairly careful guesses about when particular groups became the color they are today. And with the help of paleontologists and anthropologists, scientists can go further: They can wind the clock back and see what colors these populations were going back tens of thousands of years, says Jablonski.
“People living now in southern parts of India [and Sri Lanka] are extremely darkly pigmented,” Jablonski says. But their great, great ancestors lived much farther north, and when they migrated south, their pigmentation redarkened.
“There has probably been a redarkening of several groups of humans.”
Why We Change Color
The repigmenting process is increasingly well understood.
On the other hand, if a human is plopped down in, say, Norway, where the days can be short and there is precious little ultraviolet light, this creates problems, too. All vertebrate animals need ultraviolet light to help produce vitamin D. Vitamin D helps us absorb calcium from our food to build strong bones. If we don’t get enough ultraviolet light, we’re less likely to survive to reproductive age to produce strong-boned babies.
Hooray For Melanin
The solution is what Jablonski calls “a really cool molecule”: melanin. In different concentrations, melanin makes skin lighter or darker. Kind of like a Venetian blind, it can let UV light in or keep it out.
Melanin has evolved in many different animals. Humans have had it for a long, long time and what Jablonski and others have learned is that when early humans migrated from the equator, their melanin levels changed.
That doesn’t mean they lost their tans. It means they had very specific genetic changes that allowed them to live and successfully reproduce in less sunny places. Darwin teaches that these changes began randomly. Somebody in the population at some point had a baby, and that baby, just by chance, had a little change in its DNA that made her skin, for example, a little lighter. When that baby moved north to Europe, lighter skin gave her an advantage as a grown-up, because it helped her produce strong-boned babies who could survive and have babies of their own.
“This, in short, really created the gradation of skin color that we see in modern humans today,” says Jablonski. Her map of UV radiation levels on Earth closely mirrors the array of skin colors on Earth.
The big surprise is how fast these changes can occur.
“Our original estimates were that [skin color changes] occurred perhaps at a more stately pace,” Jablonski says. But now they’re finding that a population can be one color (light or dark) and 100 generations later — with no intermarriage — be a very different color.
Figuring 25 years per generation (which is generous, since early humans walked naked through the world — clothes slow down the rate), that’s an astonishingly short interval.
It’s “a blink of an eye,” she says.”
I do not agree with a lot of commentary geared toward “evolution” noted by the author, but the overall premise I agree with is this: your ancestors could have looked entirely different than you. In my opinion, I believe intermarriage and genetic causes like albinism is the primary cause for this.
This source is the nail in the coffin for many posts mentioned on this website. For example, this source confirms that it is not far-fetched for many of the medieval Jews and Moors in the Iberian peninsula to be black people who mated with white peoples and had mixed offspring. Why do I say this? When the Jews and Moors were expelled from the Iberian peninsula, the mixed offspring they had who weren’t expelled or who were allowed to stay mixed (we know Iberians have sub-Saharan African DNA) with the white peoples in the region. Doing this would increasingly lead to a light-skinned population again but at times darker hues and curly hair would manifest.
Going back even further, concerning the various interactions recorded in Greco-Roman mythology between southern Europeans, Africans, and peoples in the ancient near east, there are multitude of ways for intermixing to occur and result in people looking the way they are today even though their ancestors may have looked different.
This post also supports my belief that it is entirely possible for white Jews (whether they are practicing or not) and black Jews (whether they are practicing or not) be ethnically related and both descend from ancient Israel.