Hacker News Reader

Comment by api | Hacker News Reader

The most obvious evidence to me has always been that Europeans are not black. A change like the loss of melanin requires selective pressure, which in this case was likely furnished by less vitamin D as we migrated away from the equator. The pressure must have been significant since being white carries a big downside: higher vulnerability to sunburn and skin cancer. When I lived in Cali I always envied my darker skinned friends who did not have to smear goo on themselves at the beach.

I gotta say though... the world would have far less race problems had that odd little quirk of photosynthesis of a key nutrient not existed.

View on HN

> I gotta say though... the world would have far less race problems had that odd little quirk of photosynthesis of a key nutrient not existed.

Humans being humans, I’m sure nose shape, eye color (just ask Bran Sanderson), hair color/texture, or something else would readily suffice in the absence of a perceptible difference in skin tone.

> A change like the loss of melanin requires selective pressure

It does? What about genetic drift, random mutations, and artificial selection, where humans select based on qualities not necessarily conducive to survival?

There is also some evidence that this change in skin color was only widespread as recently as 8,000 years ago [1].

> which in this case was likely furnished by less vitamin D

How likely?

> The pressure must have been significant since being white carries a big downside: : higher vulnerability to sunburn and skin cancer.

Unless you are trying to hide from predators or your prey in snow? As far as skin cancer, as long as it doesn't kill you before you breed, it's not going to have a big impact on natural selection, right?

[1] https://www.smithsonianmag.com/smart-news/heres-how-european...

> It does? What about genetic drift, random mutations, and artificial selection, where humans select based on qualities not necessarily conducive to survival?

It seems unlikely to be due to these factors since there's a gradient from black to white as you move away from the equator.

One aspect of sexual selection is that a disadvantageous trait needn't kill to cause differential outcomes in reproduction. If a deficiency results lower hunting success, diminished fighting prowess, loss of mental acuity etc. the individual will be disfavored in mate selection. Iterated over generations, this eventually extinguishes some genes.

There's also the aesthetic aspect, where some traits seem to be favored simply because they are attractive to the opposite sex, which can be justified because offspring will have more favorable opportunities for reproduction, but only because the trait is well liked. A strange attractor in the genetic code, if you will. This happens across species, so I wouldn't call it artificial selection - artificial selection applied to humans is also known as eugenics.

> One aspect of sexual selection is that a disadvantageous trait needn't kill to cause differential outcomes in reproduction. If a deficiency results lower hunting success, diminished fighting prowess, loss of mental acuity etc. the individual will be disfavored in mate selection.

That makes sense, and it also supports my claim that skin cancer would likely not be a trait selected against, right? It's something that usually happens later in life and that would not be involved during mate selection.

> so I wouldn't call it artificial selection - artificial selection applied to humans is also known as eugenics.

Thanks for that distinction. If this attraction is happening naturally and unspoken, it's fair to include it as a part of natural selection. However, I do think some of it is cultural, is spoken, and goes beyond natural attraction. A common example might be the preference for lighter skin in mates that we unfortunately find in several cultures. Maybe we should start calling it eugenics instead of softening it to artificial selection.

For skin cancer narrowly, sure. I don't know what it's like to live with white skin near the equator with primitive or no clothing and no access to sunscreen, though. Losing melanin every winter, getting scorched every summer... It seems like you'd have an individual who is pretty useless for persistence hunting across the savannah. On the other side, a darker skinned individual may experience lethargy and malaise in winter at higher latitude. So we should broaden the considerations to include chronic, nonlethal conditions, and competitive sexual selection amplifies their effects. This was my only point.

> A common example might be the preference for lighter skin in mates that we unfortunately find in several cultures. Maybe we should start calling it eugenics instead of softening it to artificial selection.

You can do that if you want. People really like their mate preferences and this seems more likely to soften their perception of eugenics as a concept than the other way around.

> I gotta say though... the world would have far less race problems had that odd little quirk of photosynthesis of a key nutrient not existed.

Not really, Europeans alone are capable of the same level of mess, before and after slavery.

>I gotta say though... the world would have far less race problems had that odd little quirk of photosynthesis of a key nutrient not existed.

It's not so much about the race, but about the exploitation. Blacks and whites co-lived without racism for millenia, back when anybody could become a slave.

When around the 16th century the Europeans started to exploit latin americans, indians and blacks as slaves, they spread the various theories of racism to justify the practice (both the advance of christianity and englightenment meant that such a thing should now be justified, whereas in the ancient/pagan world just being more powerful was enough to justify making slaves of the less powerful, you didn't need an excuse).

So, if Europens where also blacks, the exploitation would just have found some other justification than skin color (kind of how Hitler didn't have much issue to discriminate against the also-white Jews).

I agree with the general conclusion about exploitation, but racist theories and justifications existed in different cultures long before the 16th century.

"Race problems" would just be replaced by individuals subjugating each other based on other physical attributes, religion or choice of text editor.

The great tabs vs. spaces war of the 28th century devastated our solar system of origin...

What's interesting is how strong the selection pressure seems to be to have melanin content adjusted to match the local conditions for sunlight. In the western hemisphere, where humans have only lived for ~20,000 years, there was already notable variations in pigmentation developing prior to 1500AD. That would make sense if vitamin D production is very important to health.

You can still get sunburn with darker skin. It just takes a lot more exposure.

Reply on news.ycombinator.com