they also carry a rich history of misunderstanding on their frequently freckled shoulders.

長久以來，他們長滿雀斑的肩膀也承擔著人們的各種誤解。

In Greek mythology, it was said that redheads turn into vampires when they die.

在希臘神話中，紅髮的人死後會變成吸血鬼。

Egyptians particularly enjoyed burning ginger virgins.

埃及人特別喜歡燒死紅頭髮的處女。

And a number of alchemist spells called for the fat of a flame-haired man.

很多煉金術士的法術則需要赤髮男性的體脂肪作為原料。

If that weren't enough, in recent years there have been headlines suggesting that redheads will actually go extinct within this century.

彷彿紅髮人還不夠慘，近幾年常看到報導宣稱紅髮在這個世紀會絕種。

A lot of the ignorance surrounding red-headedness probably has to do with the fact that although they aren't very rare,

這些對紅髮的錯誤見解或許是因為紅髮人的數量雖然不少，

redheads aren't very common either.

卻也不算多。

Though certain countries like Ireland and Scotland seem to be hosting perpetual Weasley family reunions,

儘管某些國家，例如愛爾蘭和蘇格蘭似乎總是沒完沒了地替衛斯理家族舉辦團聚派對，

gingers only make up about 1 to 2 percent of the world population,

紅髮只占世界人口的百分之一到二，

and they don't have red hair because they stole hell fire or were conceived during menstruation or bitten by a werewolf as a baby.

而他們有紅髮並不是因為他們偷取地獄之火或是在月經期間受孕或者在嬰兒時期被狼人咬。

They get their coppery hue the same way we all get our coloration: from melanin.

他們像銅一般的髮色就跟我們有不同的髮色是一樣的原因：黑色素。

Hair color is a genetic trait associated with the melanocortin one receptor, or MC1R gene.

髮色是一項基因特徵，與黑皮質素的受器，也就是MC1R基因有關。

We all have it nestled on our chromosome 16, but your red-headed friends possess a mutated version of it.

我們每個人的16號染色體裡都有這種基因，但紅頭髮的人則是在這段基因上產生變異。

This gene gives instructions for making protein receptors located on our melanocytes, the special cells that produce melanin.

這個基因負責製造蛋白質的受體指示給專門製造黑色素的黑色素細胞。

Melanin is what gives our eyes, hair, and skin their distinct hue and it comes in two varieties:

黑色素讓我們的眼睛、頭髮和皮膚不同的顏色，主要分成兩種：

eumelanin and pheomelanin.

真黑色素和褐黑素。

A person producing mostly eumelanin will have darker hair and skin that tans easily and is better protected from the sun's UV radiation.

可以製造大量真黑素的人會有比較黑的頭髮和皮膚，容易曬黑且較能防止太陽的 UV 輻射。

But if you're brewin' mostly pheomalinin, you're gonna have reddish or blonde hair,

但如果你大部分製造棕黑素，那你會有紅髮或金髮，

fair skin that burns easily because it's not naturally protected from the sun.

還有白皮膚，容易曬傷則是因為皮膚天生無法保護來自太陽的傷害。

That's why fair folk have an increased risk of skin cancer.

這就是為什麼白皮膚的人得到皮膚癌的風險較高。

It's that MC1R gene that dictates what kind of melanin you get.

MC1R 基因決定你能得到什麼樣的黑色素。

If the gene is activated, you'll end up with more eumelanin and will be darker complected.

如果這個基因比較活躍，你會有較多真黑素和較黑的膚色 。

If those receptors don't trigger, your cells pump out the fair pheomelanin.

如果這個受體沒有被啟發，你的細胞便會大量釋放白色褐黑素。

We're not exactly sure just how far back the trait goes,

我們不能確定這個特徵究竟是何時出現的，

but scientists recently extracted a version of the ginger gene from the remains of two Neanderthals indicating that at least some of them were redheads.

但科學家最近從兩個尼安德特人的遺骸中採集到一種紅髮的基因證明至少有些尼安德特人是紅髮。

However, the gene was a variant.

然而，這個基因是個變體。不是在現代人身上顯現出來的。

Not the one present in modern humans indicating the mutation evolved independently from human red-headedness in an example of convergent evolution.

這顯示出紅髮人的演化是獨立發展的，是一個趨同的演化例子。

Now you may be wondering why both humans and Neanderthal genes would perpetuate a skin type so prone to sunburns.

現在你可能會想，為什麼人類和尼安特人可以讓這麼容易曬傷的皮膚基因存在這麼久。

Well, it has to do in part with geography.

這個則會牽涉到地理。

People from equatorial regions usually have darker hair and skin to better protect them from the sun's radiation.

赤道地區的人們通常有較黑的頭髮和皮膚以保護他們免於太陽輻射的傷害。

Whereas fair skin and hair is more prevalent in northern areas with lower levels of sunlight.

然而白皮膚和髮色的人多存在於北方，比較沒有陽光的地方。

The farther you move from the equator, the more that selective pressure for darker pigmentation lessens and the mutant MC1R genes are not selected against so they can spread throughout a population.

你離赤道越遠對於需要黑色素沉澱的壓力就越少，突變的 MC1R 細胞就不會作用，所以這個特徵就會在人口中散播。

And then, hello Scotland.

然後，你好蘇格蘭！

The successful spread of this mutation may be because fair skin is better at generating vitamin D,

這種基因變化的成功地傳播或許是因為白皮膚比較善於製造維他命 D，

which could have actually given flame hairs an evolutionary advantage in the perpetually cloudy North.

這在常年多雲的北方給了紅髮演化上的優勢。

But you may have also heard that gingers are kinda babies when it comes to pain and I hate to say it but there's some truth to that.

但你可能會聽說過紅髮人非常怕痛簡直像個嬰兒一樣 我很不想承認，但這是有事實根據的。

A couple of studies funded by the National Institutes of Health found that redheads are actually more sensitive to thermal pain, or excessive heat and cold,

由美國國立衛生研究院贊助的研究發現紅髮對於熱痛，或是極端的冷熱是更敏感的，

and that they actually required, on average, nearly 20 percent higher doses of anesthetic than their dark-haired counterparts.

比起黑髮人，他們通常需要多百分之二十的麻醉劑。

And researchers aren't entirely sure what's going on here but one hypothesis connects pain tolerance to that tricksy MC1R gene.

學者並不完全確定這之間的關聯但一項假設認為對於痛的忍受度和刁鑽的 MC1R 基因有關。

Since the gene is responsible for the receptors of pigment-producing hormones,

這個基因和製造色素的賀爾蒙受器有關，

they may also interact with similar molecules like endorphins,

他們也會跟相似的分子互相影響，例如內啡肽，

our body's natural painkillers.

也就是我們體內天生的止痛劑。

And finally, what about that great imminent ginger extinction?

最後，關於即將來到的紅髮滅絕？

That, I can tell you, is bogus.

這個，我保證只是廢話連篇。

Yes, the mutation is a recessive trait meaning that both parents have to carry the allele or gene variant for it to produce a red-haired offspring.

是的，這個變化是隱性性狀特徵亦即父母都要有等位基因或是變異基因才能生出紅髮後代。

But that still means that even if say,

但他還是代表，今天我們假設

four percent of the population actually has red hair, perhaps thirty percent still carry that gene keeping the potential for ginger generations alive and not just in the UK.

地球上百分之四的人口是紅髮，可能有百分之三十的人仍然帶有這種基因使得紅髮世代可以延續在，而且不是只在英國。

So rest assured gingers are gonna be passing along their genes and supporting the sunscreen industry for a very long time.

所以放心吧！紅髮會把他們的基因傳下去且繼續支持防曬乳產業。

Thank you for watching this SciShow dose and a big thanks to our subscribers on Subbable without whom you would not be watching this.

感謝收看 SciShow 且大力感謝我們在 Snubbable 上的訂閱者，沒有你們就沒有這支影片！

Would you like us to tweet you a picture from our beautiful studio or add your custom message to our doobliedoo?

不知道你們會不會希望我們推特美麗的工作室的圖片？或是將你們的訊息放到我們的 doobliedoo？

To learn more about these and other exclusive perks go to Subbable.com.

想知道更多這類訊息和看其他影片請上 Subbable.com。

And if you have an idea you'd like us to cover or a question or comment, leave it for us in the comments below and don't forget to follow us on Facebook and Twitter.

如果你有什麼想法問題或評論想要提供給我們，請在留言欄留言，且別忘了在臉書和推特追蹤我們！

And go to YouTube.com/SciShow and subscribe.

並前往 YouTube.com/SciShow 訂閱！