How Europeans evolved white skin (2015) • Hacker News Board

Re: How Europeans evolved white skin (2015)

#61

Post by z2210558 » Sat, Mar 17, 2018, 8:39 PM UTC

lordnacho wrote: post #56

defen wrote: post #21

Milk does not naturally contain very much vitamin D, so that's a silly reason to expect lactase persistence to have evolved. A much simpler explanation is that it massively increases the calories available to pastoralist populations. SLC24A5 is an interesting gene - I don't think Vitamin D is the full story. It's an SNP that is alone responsible for 25-40% of skin tone difference between Europeans and West Africans,…

What's the story with East Asians? They have light skin as well, right? Is it the same mutation?

No it's different, and thought to have evolved independently. See e.g. http://journals.plos.org/plosgenetics/article?id=10.1371/jou...

Re: How Europeans evolved white skin (2015)

#62

Post by amriksohata » Sat, Mar 17, 2018, 8:52 PM UTC

lallysingh wrote: post #52

quotemstr wrote: post #37

Earlier quoted context omitted.

No it wasn't

Alright you two. Time to pull them out and compare. References please.

Mostly because there is no evidence it happened infact most evidence refutes it and if anything says it happened the other way round

http://www.huffingtonpost.com/rajiv-malhotra/how-europeans-m...

Re: How Europeans evolved white skin (2015)

#63

Post by HumanDrivenDev » Sat, Mar 17, 2018, 9:01 PM UTC

amriksohata wrote: post #62

lallysingh wrote: post #52

Earlier quoted context omitted.

Alright you two. Time to pull them out and compare. References please.

Mostly because there is no evidence it happened infact most evidence refutes it and if anything says it happened the other way round http://www.huffingtonpost.com/rajiv-malhotra/how-europeans-m...

So your source is from tabloid news?

I look forward to a rebuttal from the Daily Mail.

Re: How Europeans evolved white skin (2015)

#64

Post by CryptoPunk » Sat, Mar 17, 2018, 9:02 PM UTC

defen wrote: post #21

Milk does not naturally contain very much vitamin D, so that's a silly reason to expect lactase persistence to have evolved. A much simpler explanation is that it massively increases the calories available to pastoralist populations. SLC24A5 is an interesting gene - I don't think Vitamin D is the full story. It's an SNP that is alone responsible for 25-40% of skin tone difference between Europeans and West Africans,…

>>However it's also under selection in places like the Ethiopian highlands, where sun exposure is presumably not an issue.

The Ethiopian highlands have been historically productive in agriculture. Agricultural diets contain less Vitamin D, increasing the selective pressure for lighter skin tones.

The highlands are also cooler than other regions of Africa at similar latitudes, resulting in more clothing being required on average. More clothing necessitates more UVB absorption per unit of skin exposed, which would further select for lighten skin tones.

Re: How Europeans evolved white skin (2015)

#65

Post by lower » Sat, Mar 17, 2018, 9:19 PM UTC

defen wrote: post #41

zeotroph wrote: post #31

Earlier quoted context omitted.

> vitamin D That is the driving force for lighter skin (unless your diet is mostly fish, such as the Inuit). Skin gets darker again when migration towards sunnier climates happens: while UV light is essential for the synthesis of D3, it also destroys folic acid / vitamin B9 [1], which is essential when the neural tube of a fetus is being formed. And since this mutation is so very visible, maybe here sexual selection…

I'm not saying vitamin D isn't involved; I'm just wondering whether it's the whole story. Is this single nucleotide change in SLC24A5 really the only way to decrease melanin production without having other harmful side effects? Naively I would expect lots of ways to have a loss-of-function mutation; why is this one so common? Sexual selection could be a factor, but that is not politically correct to say.

> Is this single nucleotide change in SLC24A5 really the only way to decrease melanin production without having other harmful side effects? Naively I would expect lots of ways to have a loss-of-function mutation

In Asia, light skin evolved separately and is using different genes.

https://en.wikipedia.org/wiki/Human_skin_color#East_Asia

Re: How Europeans evolved white skin (2015)

#66

Post by pbhjpbhj » Sat, Mar 17, 2018, 9:24 PM UTC

HumanDrivenDev wrote: post #63

amriksohata wrote: post #62

Earlier quoted context omitted.

Mostly because there is no evidence it happened infact most evidence refutes it and if anything says it happened the other way round http://www.huffingtonpost.com/rajiv-malhotra/how-europeans-m...

So your source is from tabloid news? I look forward to a rebuttal from the Daily Mail.

HuffPo might have something itself.

http://www.thehindu.com/opinion/op-ed/too-early-to-settle-th... has this:

>"With the information currently available, it is difficult to deduce the direction of haplogroup R1a migration either into India or out of India, although the genetic data certainly show that there was migration between the regions. Currently, CSIR-CCMB and Harvard Medical School are investigating a larger number of samples, which will hopefully throw more light on this debate." //

Re: How Europeans evolved white skin (2015)

#67

Post by selimthegrim » Sat, Mar 17, 2018, 9:36 PM UTC

TheCoelacanth wrote: post #42

primaryobjects wrote: post #13

Earlier quoted context omitted.

Cheese and yogurt both have lactose.

Some types of cheese and yogurt have greatly reduced amounts of lactose compared to plain milk. Many people who can't tolerate plain milk can still tolerate some types of cheese and yogurt.

Yes, this is what I meant.

Re: How Europeans evolved white skin (2015)

#68

Post by IvanDraga » Sat, Mar 17, 2018, 9:42 PM UTC

giardini wrote: post #19

I was surprised to see the article state "The modern humans who came out of Africa to originally settle Europe about 40,000 years are presumed to have had dark skin, which is advantageous in sunny latitudes." "presumed"??!! I've always thought there was some scientific evidence for this and not mere presumption. Is there not some evidence about the skin coloration of our African ancestors of different periods?

Theory "Out of Africa" is debunked for a quite a while already

Re: How Europeans evolved white skin (2015)

#69

Post by thevardanian » Sat, Mar 17, 2018, 9:43 PM UTC

_emacsomancer_ wrote: post #22

amriksohata wrote: post #4

I'm struggling to understand this, tallness? Didn't that only happen to some European countries in the past hundred years? Because of diet? The ability to digest milk? The Hindu civilisation is one of the oldest in the world and milk and cows are very much a first class thing, suggesting it's not jsut Europeans that could digest milk, but other culture for a very long time. Maybe I'm reading this wrong but how does t…

Some of this is tricky to untangle, because it's easy to intentionally or unintentionally conflate genetics/race, culture, and language, but at least culturally/linguistically the people of North India are related to the majority of the peoples of Europe. So Sanskrit, Hindi/Urdu, Bengali, Gujarati, Punjabi, Kashmiri, Assamese, Nepali etc. are all Indo-European languages, as are Latin, Greek, Russian, Danish, Icelandi…

>Which presumably correlates in part to the India having experienced a large number of migrations over a fairly long period of time.

This meme will end up being the last causality in a long line of poorly written narratives extrapolated from either poor data, or poorly interpreted data. That is we completely ignore a lot of factors. For example both South Indians, and North Indians are from a same divergent ancestor tens of thousands of years ago.

Another example is the eponymous R1 signature that people use to construct a particular narrative leave out the fact that R1 originated at the very least in Asia. Where exactly scientist have argued anywhere from Central, to South, to East Asia.

A more sane, and logical argument would be that at different points in time people have immigrated to India, and emigrated out of India. And not just India, through Eurasia people have traded genetics, linguistics, and culture with each other for at least 80,000 years.

That is there is not just a single large number of migration from one area to another, but multiple, and in various directions.

Re: How Europeans evolved white skin (2015)

#70

Post by golemiprague » Sat, Mar 17, 2018, 9:47 PM UTC

roywiggins wrote: post #24

irrational wrote: post #20

Earlier quoted context omitted.

You might want to read some introductory anthropology textbooks. For as long as there have been humans it has been us against them. Them/the others/the strangers/the not us are dangerous and cannot be trusted. There are specific rituals that an other must go through to become a part of the community - the means by which one of the others can become one of us. What separates us from them? It might be skin color, it mi…

You're not wrong, but it's worth saying that contemporary racism is qualitatively quite different from, say, Greek ideas about their own superiority or tribal conflicts generally. It's very nearly a caste system- you can be born next door, speak the same language, eat the same food, think the same way, and you will be treated differently based on racial judgements. That's quite different from "we Hill People hate the…

What do you mean by "speak the same language, eat the same food, think the same way"? It is pretty evident that this is not the case, there are a lot of variations between different groups of people and in many time it is divided by racial lines. Cast systems on the other hand is exactly the opposite, it is a system that divide people on family lineage even though all else is similiar.