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How many changes in DNA make a caucasian?
Posted by: sekker
Date: July 08, 2020 09:46PM
With all of the DNA data on humans, I thought I'd post a little-known but super cool genetic story.

For those of us with light skin - Northern Europeans including most Germans, Irish, UK, Scandinavia etc, we ALL share a single genetic change. One change in 3 billion. A single 'base' of DNA - A,C,G or T. 2 bits of information.

(there are over 100 genetic loci that make up different skin colors such as red hair, etc. And this does not explain why Asians are lighter skinned than Africans).

But it's amazing - a single nucleotide change and the world thinks and treats us differently. WE ARE ALL THE SAME.

[www.npr.org]

Here's the original article:
[science.sciencemag.org]
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Re: How many changes in DNA make a caucasian?
Posted by: PeterB
Date: July 08, 2020 09:56PM
Interesting (and bizarre) ... a cation exchanger in melanocytes, so I presume it's affecting the production of melanin.

Thanks for posting this ... might use it as a case study in one of the courses I teach. Certainly it's not the case though that a single gene/allele determines light versus dark skin, since of course there are such variations in skin tone across the globe. (I'm assuming you didn't mean to say "skin colors such as red hair"... red hair being caused by at least one particular mutation in MC1R...)

I think the bigger picture point you're making, which is well taken, is that we're basically all just VERY slight variants / allele versions of each other. Minor single base changes here or there. My recollection is that human beings are 99.99% similar to identical DNA to each other... very minor differences between any of us.




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)
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Re: How many changes in DNA make a caucasian?
Posted by: sekker
Date: July 08, 2020 10:06PM
Quote
PeterB
Interesting (and bizarre) ... a cation exchanger in melanocytes, so I presume it's affecting the production of melanin.

Thanks for posting this ... might use it as a case study in one of the courses I teach. Certainly it's not the case though that a single gene/allele determines light versus dark skin, since of course there are such variations in skin tone across the globe. (I'm assuming you didn't mean to say "skin colors such as red hair"... red hair being caused by at least one particular mutation in MC1R...)

I think the bigger picture point you're making, which is well taken, is that we're basically all just VERY slight variants / allele versions of each other. Minor single base changes here or there. My recollection is that human beings are 99.99% similar to identical DNA to each other... very minor differences between any of us.

Thanks for the correction on hair color - I mistyped. Though the red hair locus is also fascinating.

But the huge surprise of this paper was that a single change is critical for what we call Caucasian skin color tones.

I happen to know the scientist discoverer - this was a complete fluke. He was studying cancer loci, and he found this super small change linked to a skin color locus in fish, then checked in people.

I posted on this side as his discovery has led him to be targeted by the K K K - amazing as he lives in PA.



Edited 1 time(s). Last edit at 07/08/2020 10:07PM by sekker.
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Re: How many changes in DNA make a caucasian?
Posted by: PeterB
Date: July 08, 2020 10:26PM
Quote
sekker
Quote
PeterB
Interesting (and bizarre) ... a cation exchanger in melanocytes, so I presume it's affecting the production of melanin.

Thanks for posting this ... might use it as a case study in one of the courses I teach. Certainly it's not the case though that a single gene/allele determines light versus dark skin, since of course there are such variations in skin tone across the globe. (I'm assuming you didn't mean to say "skin colors such as red hair"... red hair being caused by at least one particular mutation in MC1R...)

I think the bigger picture point you're making, which is well taken, is that we're basically all just VERY slight variants / allele versions of each other. Minor single base changes here or there. My recollection is that human beings are 99.99% similar to identical DNA to each other... very minor differences between any of us.

Thanks for the correction on hair color - I mistyped. Though the red hair locus is also fascinating.

But the huge surprise of this paper was that a single change is critical for what we call Caucasian skin color tones.

I happen to know the scientist discoverer - this was a complete fluke. He was studying cancer loci, and he found this super small change linked to a skin color locus in fish, then checked in people.

I posted on this side as his discovery has led him to be targeted by the K K K - amazing as he lives in PA.

The MC1R story is also pretty interesting ... it's been said that the story of redheads being in genetic decline is wrong, but ... with increases in UV radiation on the planet because of the ozone layer disappearing, I would guess that there might be an increased selection pressure against red hair -- and so their days might be numbered after all. grinning smiley

And that's terrible about him being targeted. Zebrafish are a great model ... I had a fish lab working downstairs from me when I was doing my grad school work.

I'm sure you've also seen this story ... ties in with what you posted:

[thesocietypages.org]
[www.dailymail.co.uk]

(edit: added an extra link because the dailymail website is absolutely overrun with intrusive ads!)




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)



Edited 1 time(s). Last edit at 07/08/2020 10:29PM by PeterB.
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Re: How many changes in DNA make a caucasian?
Posted by: Steve G.
Date: July 08, 2020 10:26PM
My mother made me a criminal.
If I give her the yarn, will she make me one, too?
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Re: How many changes in DNA make a caucasian?
Posted by: RgrF
Date: July 08, 2020 11:26PM
I posted on this side as his discovery has led him to be targeted by the K K K - amazing as he lives in PA.


K acolytes read Science Magazine? Must have been passed on thru some sort of cartoon like interpretation.
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Re: How many changes in DNA make a caucasian?
Posted by: NewtonMP2100
Date: July 08, 2020 11:34PM
.....is it a large cauc........asian.....????



_____________________________________

I reject your reality and substitute my own!
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Re: How many changes in DNA make a caucasian?
Posted by: Janit
Date: July 09, 2020 07:27AM
I feel a thriller plot premise coming on, using CRISPR gene therapy to repair the defect in this gene. Dump the vector in the water supply, and watch heads explode as white people slowly darken, and stay that way.



Edited 1 time(s). Last edit at 07/09/2020 07:40AM by Janit.
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Re: How many changes in DNA make a caucasian?
Posted by: sekker
Date: July 09, 2020 07:55AM
Quote
Janit
I feel a thriller plot premise coming on, using CRISPR gene therapy to repair the defect in this gene. Dump the vector in the water supply, and watch heads explode as white people slowly darken, and stay that way.

It'd be easy to design the CRISPR gRNA to do it, too, via a new method that's coming out...

I want to congratulate this side, I've never had a conversation on this topic not instantly wander deeply into the political spectrum around race.

Note also, that this is a DEFECT. If you have this allele, you are 3x more likely to get skin cancer and other related malignancies because this protein that is conserved from fish to people is highly dysfunctional in Caucasians. This CRISPR approach would be 'correcting' this molecular defect!



Edited 2 time(s). Last edit at 07/09/2020 07:56AM by sekker.
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Re: How many changes in DNA make a caucasian?
Posted by: pdq
Date: July 09, 2020 08:18AM
Well, it’s an adaptive mutation. Melanin is great for protecting the skin from solar irradiation, but we need a certain amount to get through to make vitamin D (out of a starting material of cholesterol, BTW).

Scientists noted long ago that the darkness of one’s skin is very strongly correlated with the amount of solar irradiation received in the area your ancestors lived in:



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Re: How many changes in DNA make a caucasian?
Posted by: sekker
Date: July 09, 2020 09:10AM
Quote
pdq
Well, it’s an adaptive mutation. Melanin is great for protecting the skin from solar irradiation, but we need a certain amount to get through to make vitamin D (out of a starting material of cholesterol, BTW).

Scientists noted long ago that the darkness of one’s skin is very strongly correlated with the amount of solar irradiation received in the area your ancestors lived in:




That's a great story, and might be right.

There is also evidence that lighter skin is a defect, and people are smart - that people with lighter skin naturally migrated to get away from the cancer-inducing sun.

Or a combination of both.

The specific allele that is found in all current Caucasians is a relatively new event (in human evolution terms), and seems to have been singular as everyone has the exact same sequence change.

Oh - and it's 99.999999% certain that Moses and Jesus did NOT have this sequence variant...
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Re: How many changes in DNA make a caucasian?
Posted by: rjmacs
Date: July 09, 2020 09:52AM
Interesting story, sekker. It is amazing how the more we learn about genetics, the more clearly fictional 'race' is as a biological category.

In this discussion so far, it's worth pointing out that the term "Caucasian" is just a description of a fictional group. What a powerful made up category that one has turned out to be.



rj
AKA
Vreemac, Moth of the Future
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Re: How many changes in DNA make a caucasian?
Posted by: sekker
Date: July 09, 2020 10:54AM
Quote
rjmacs
Interesting story, sekker. It is amazing how the more we learn about genetics, the more clearly fictional 'race' is as a biological category.

In this discussion so far, it's worth pointing out that the term "Caucasian" is just a description of a fictional group. What a powerful made up category that one has turned out to be.

I used that abbreviation to help with sci comm, and it is also prominently in areas like India where they are literally meaning 'people from the Caucasus Mountains' in their genetic lineage work. They were dealing with over 200 recognized languages as surrogate for race in that work.

EDIT: removed an out of date link.



Edited 1 time(s). Last edit at 07/09/2020 10:57AM by sekker.
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Re: How many changes in DNA make a caucasian?
Posted by: PeterB
Date: July 09, 2020 12:40PM
Quote
sekker
Quote
pdq
Well, it’s an adaptive mutation. Melanin is great for protecting the skin from solar irradiation, but we need a certain amount to get through to make vitamin D (out of a starting material of cholesterol, BTW).

Scientists noted long ago that the darkness of one’s skin is very strongly correlated with the amount of solar irradiation received in the area your ancestors lived in:




That's a great story, and might be right.

There is also evidence that lighter skin is a defect, and people are smart - that people with lighter skin naturally migrated to get away from the cancer-inducing sun.

Or a combination of both.

The specific allele that is found in all current Caucasians is a relatively new event (in human evolution terms), and seems to have been singular as everyone has the exact same sequence change.

Oh - and it's 99.999999% certain that Moses and Jesus did NOT have this sequence variant...

I actually made the argument on the other side that, in the face of a damaged/depleted ozone layer, the mutation might be selected against ... in the same way that red hair may be. [www.nasa.gov]




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)
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Re: How many changes in DNA make a caucasian?
Posted by: sekker
Date: July 09, 2020 01:25PM
Quote
PeterB
Quote
sekker
Quote
pdq
Well, it’s an adaptive mutation. Melanin is great for protecting the skin from solar irradiation, but we need a certain amount to get through to make vitamin D (out of a starting material of cholesterol, BTW).

Scientists noted long ago that the darkness of one’s skin is very strongly correlated with the amount of solar irradiation received in the area your ancestors lived in:




That's a great story, and might be right.

There is also evidence that lighter skin is a defect, and people are smart - that people with lighter skin naturally migrated to get away from the cancer-inducing sun.

Or a combination of both.

The specific allele that is found in all current Caucasians is a relatively new event (in human evolution terms), and seems to have been singular as everyone has the exact same sequence change.

Oh - and it's 99.999999% certain that Moses and Jesus did NOT have this sequence variant...

I actually made the argument on the other side that, in the face of a damaged/depleted ozone layer, the mutation might be selected against ... in the same way that red hair may be. [www.nasa.gov]

Happening already in Oz. Much higher skin cancer Down Under.
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Re: How many changes in DNA make a caucasian?
Posted by: Rolando
Date: July 09, 2020 11:18PM
That reminds me of a bizarre website I found once. I totally wormholes, but its main thesis was that white people are basically Albino Dravidians! Fascinating site...
[realhistoryww.com]

A lot of pseudoscience here, but fascinating.
As I once told a young lady from Cameroon, "we're all African, so when I say "black" please understand I mean "of Post-Prehistoric SubSaharan derivation"



San Antonio, TX (in the old city)


"All that is required for evil to prevail is for good men to do nothing." - Edmund Burke
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"To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public." - Theodore Roosevelt (1918)

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