Global Distribution of Skin Colour

[Satchmo Distel]

Something I am teach today which I though was worth sharing.

George Chaplin and Nina Jablonski (who are also married) produced a model showing how skin colour evolved relative to UV radation. Chaplin depicts it on this map:

https://www.npr.org/templates/story/...ryId=100057939

Jablonski argues that dark pigment evolved to block the UVA that destroys folate whereas white skin is to absorb UVB needed to manufacture Vitamin D. Video here:

https://www.youtube.com/watch?v=ww1t19H2b-k

[Kevin S]

Will you get to mention the discovery about Cheddar Man from earlier in the year?

https://www.theguardian.com/science/...alysis-reveals

[Rogin the Armchair fan]

The extraordinary rapidity of such a genetic change in a small population has to evidence my* theory that environmental factors required by a population drive genetic mutation from one generation to the next by a mechanism as yet unknown. (See also: the millennial generation are almost all 2" taller than their own grandparents). They simply wouldn't come about from random mutation and an assumption about more successful breeding. Not in that timeframe.

*I'm sure some proper people have suggested this before me.

[Satchmo Distel]

Will you get to mention the discovery about Cheddar Man from earlier in the year?

https://www.theguardian.com/science/...alysis-reveals

Definitely, many thanks

[Patrick Thistle]

The Millennial Generation are on average taller than their grandparents thanks to better nutrition in childhood.

[Fussbudget]

The extraordinary rapidity of such a genetic change in a small population has to evidence my* theory that environmental factors required by a population drive genetic mutation from one generation to the next by a mechanism as yet unknown. (See also: the millennial generation are almost all 2" taller than their own grandparents). They simply wouldn't come about from random mutation and an assumption about more successful breeding. Not in that timeframe.

*I'm sure some proper people have suggested this before me.

Lamarck?

[Satchmo Distel]

Yes. Probably some genes are sensitive to environment anyway. Those that we associate with "intelligence", maybe. Nature/nurture is a false dichotomy.

[anton pulisov]

Nature/nurture is a false dichotomy.

Big name scientists thrive on false dichotomies.

[Fussbudget]

Erm. I was being facetious, Lamarckism is widely discredited. All evidence suggests that DNA mutations caused by environmental factors can't be passed on the next generation.

Rogin/Satchmo, epigenetics is probably what you're after.

[Rogin the Armchair fan]

The Millennial Generation are on average taller than their grandparents thanks to better nutrition in childhood.

Yes, but is that now something that's hard-wired into their genes? If my 5'8" daughters reverted to feeding them a 1950s diet would their kids only be 5'6"? Or would they, because it's already hard wired into them from their parents?

[anton pulisov]

Yes, but is that now something that's hard-wired into their genes? If my 5'8" daughters reverted to feeding them a 1950s diet would their kids not grow as tall? Or would they, because it's already hard wired into them from their parents?

Yeah, the poor nutrition would probably stunt their growth.

There must be studies done on identical twins separated at birth.

[WOM]

There must be studies done on identical twins separated at birth.

Mengele, et. al. @ 1943

[Patrick Thistle]

Yes, but is that now something that's hard-wired into their genes? If my 5'8" daughters reverted to feeding them a 1950s diet would their kids only be 5'6"? Or would they, because it's already hard wired into them from their parents?

Most likely. A maximum height might be genetically predetermined but achieving it is dependent on having the right environment, particularly access to food.

[Tactical Genius]

Regarding height difference.

The average millenial Brits grandparents would have grown up during or just after the war so would have lived under food shortages and rationing during their early years.

As for the global distribution of skin colour, it is (in the last 6000 years) more to do with human migration as a result of war/conquest or a response to climate change as it is to do with human adaptations to the burning sun or freezing cold.
Cheddar man was the final nail in the long held myth that human skin colour automatically lightened as they migrated out of Africa towards the poles. The ancient Romans had some interesting things to say about the appearance of Ancient Briton's.

[WOM]

As for the global distribution of skin colour, it is (in the last 6000 years) more to do with human migration as a result of war/conquest or a response to climate change as it is to do with human adaptations to the burning sun or freezing cold.

How is 'response to climate change' different from 'adaptation to the freezing cold'?

Cheddar man was the final nail in the long held myth that human skin colour automatically lightened as they migrated out of Africa towards the poles.

Is anyone suggesting the 'lightening' happened overnight? I don't understand how one man undoes the entire body of scientific study. People are typically much darker nearer the hottest climes on earth and much paler toward the less sun-soaked areas. Surely you're not suggesting this is some fluke.

[Tactical Genius]

Mr Candid

How is 'response to climate change' different from 'adaptation to the freezing cold'?

I am talking about human migration and not genetic adaptation. also climate change can mean any one of the following:

Rivers silting up or changing direction
Rising sea levels
drought
desertification
opening\closing of land bridges

This causes changes in their food sources or availability of food leading to migration.
Hopefully that makes sense.

"Is anyone suggesting the 'lightening' happened overnight? I don't understand how one man undoes the entire body of scientific study."

As that wasn't really based in scientific fact. I was taught in School people in certain parts of the world looked a certain way due to their local climate. I knew that was crap instantly as it didn't explain to my why indigenous south Americans were only slightly brown, and the massive disparity in skin pigmentation between the Indonesians and the inhabitants of Papua New Guinea who live on the same island chain.

Also a cursory look at human history tells a story of constant migration so we are rarely anywhere long enough to start to adapt physically to the surroundings. There is also the constant changing of the earth's climate from Warm/Ice ages around the poles or Wet/Dry ages in the tropics.

People are typically much darker nearer the hottest climes on earth and much paler toward the less sun-soaked areas. Surely you're not suggesting this is some fluke.

I never did suggest that. What i am saying is that it is more to do with human migration than it is with people adapting to their environment. If it wasn't that an indiginous Peruvian and Brazillian would look like an African. after all, their ancestors have been cut off from the human gene pool for the last 13-15,000 years so they should have good a lot darker as they migrated their way down the Americas.
Unless you are an Albino, we all have the ability to go a couple of shades darker when exposed to alot of sunlight as your body adapts and produces additional Melanin. On the other hand, Black people born and raised in the UK are slightly lighter skinned than their family members in Africa and the Carribbean.