How many generations to change skin colour?

[Blake]

@Aji_de_Gallina

(my bolding)
How is this defective? I know you’re trying to kick some racist ass (deservedly) but bieng white is not defective in any scientific definition. Many adaptation could be “defect” by your definitions.

I don’t know enough about this exact subject to comment, but many adaptations are indeed the result of defective genes. Sickle cell and lactose tolerance being the two most obvious examples. Genes are supposed to code for functional proteins. If the protein it codes for is defective (or isn’t even expressed) then the gene is indeed defective.

[Aji_de_Gallina]

@Blake

I don’t know enough about this exact subject to comment, but many adaptations are indeed the result of defective genes. Sickle cell and lactose tolerance being the two most obvious examples. Genes are supposed to code for functional proteins. If the protein it codes for is defective (or isn’t even expressed) then the gene is indeed defective.

It is defective only you needed it to survive, the “defect” may be an adaptation, i.e. not doing what the “good” gene did would be better.

[Dr.Drake]

A defect (from the mechanical point of view) can be an improvement (from the functional or holistic points of view). I fail to see the problem you’re having with the word. “Defective” doesn’t mean “evil,” it just means it does not work as it had been working.

[Aji_de_Gallina]

@Dr.Drake

A defect (from the mechanical point of view) can be an improvement (from the functional or holistic points of view). I fail to see the problem you’re having with the word. “Defective” doesn’t mean “evil,” it just means it does not work as it had been working.

I’ll settle for that. OK

[Indian]

A related link from new scientistmagazine .

[Sailboat]

Yeah, a defective lock on the gate that lets the concentration camp inmates escape is still defective even though the result of that failure is a positive good.

[DSeid]

To the op:

Some pigmentary changes can happen in the blink of a (baby blue) eye.

All blue-eyed people have a single, shared ancestor, scientists say. And all those baby blues are the result of a genetic mutation that occurred between 6,000 and 10,000 years ago … A genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a ‘switch,’ which literally ‘turned off’ the ability to produce brown eyes

In point of fact human evolution appeared to pick up speed in the last 40,000 and really step it up in the last 10,000.

For example, in Europe natural selection has favored genes for pigmentation like light skin, blue eyes, and blond hair. Asians also have genes selected for light skin, but they are different from the European ones.

“Europeans and Asians are both bleached Africans, but the way they got bleached is different in the two areas,” Harpending said.

And then there is this.

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. …

… if we look back only 100 or 200 generations (that’s as few as 2,500 years), “almost all of us were in a different place and we had a different color.” …

… 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.

[HorseloverFat]

Afrikaaners have been living in SA for over 300 years, and they seem every bit as white as modern day Dutch people, so it doesn’t look like the process is even perceptable in that time frame.

Theyre getting vitamin D from milk and vitamins. Skin color doesnt matter when youre technologically advanced enough to put vitamin D in everything.

[Really_Not_All_That_Bright]

@HorseloverFat

Theyre getting vitamin D from milk and vitamins. Skin color doesnt matter when youre technologically advanced enough to put vitamin D in everything.

Not to mention they mostly live indoors, and the risk of death from heatstroke or exposure in general is virtually nil- certainly not enough to have a significant impact on reproduction rates.