评论
打印
This episode is sponsored by Brilliant.org
本期视频由Brilliant.org赞助。
Put a scorpion under a blacklight and it'll light up like a neon sign.
将一只蝎子放在黑光诱虫灯下，它会像霓虹灯闪光。
And they aren't the only organisms that glow in this way.
它们并非唯一一种能以这种方式发光的生物体。
We've found other invertebrates as well as fish, amphibians, reptiles, and birds that do the same kind of thing
我们发现其他无脊椎动物以及鱼类、两栖动物、爬行动物和鸟类都能如此
there's even a flying squirrel that glows neon pink. All of these are examples of biofluorescence.
甚至有一种鼯鼠也能发出霓虹粉光。这些都属于生物荧光。
And this ancient, common, and somewhat mysterious trait might be a signature of life itself.
这一古老又常见的神秘特质是生命自带的标签。
Normally, when you think of animal colors, you think of pigments in their fur, skin, or feathers,
正常情况下，当你想到动物颜色时，你会想到它们皮毛、皮肤或羽毛上的颜色，
which reflect certain wavelengths of light.
这些可以反射光的某种波长。
Red pigments, for example, absorb blue and green light, but reflect red wavelengths, hence why they look red to us.
例如红色吸收蓝光和绿光，却能反射红色波长，所以我们看到的是红色。
Fluorescence, though, is different. Things that fluoresce don't just reflect light, they're actually creating new light of their own.
虽然荧光不同。能发出荧光的事物不仅仅反射光，它们也能创造新的光。
When a fluorescent molecule is struck by the right particle of light, it absorbs it, and because of that little bit of energy,
当一个荧光分子撞上恰当的光粒子时，它会吸收它，并且由于这一点点能量，
it becomes excited for just a handful of nanoseconds.
它会兴奋几纳秒的时间。
Then, it relaxes and — this is the important bit — it kicks out a new photon that has less energy than the original.
然后再放松下来—这是重要的一点—它会将那个没有原光子那么活跃的新光子踢出去。
So the light emitted has a longer wavelength and therefore is a new color.
所以发出的光有一段更长的波长，新颜色就这样产生了。
This isn't unique to one single chemical. Lots of chemicals can do this. There are even rocks and minerals that fluoresce.
这并非是一种化学物质所特有的。很多化学物质都可以。甚至是岩石和矿物质都可以发出荧光。
But many of the fluorescent chemicals we see in animals share a certain structure — several carbon rings combined together.
但我们在动物身上看到的很多荧光化学物质都是同一种结构—几个碳环相结合。
Take the famous green fluorescent protein or GFP, it glows thanks to some rings in the center of the protein.
例如绿色荧光蛋白（GFP），它能够发光是因为位于蛋白质中间的一些碳环。
And how these proteins evolved is a bit of a scientific head-scratcher.
这些蛋白质是如何进化的仍是个科学难题。
Fluorescent proteins can be found in animals that aren't closely related.
在一些亲缘关系甚远的动物身上也发现了这种荧光蛋白。
And that suggests that they arose independently multiple times, a phenomenon known as convergent evolution.
这表明这些进化是独立的且发生过多次的，这种现象被称为趋同进化。
On the other hand, many of them look very similar, perhaps a little too similar to be separate evolutionary efforts.
另一方面，其中很多长得很像，就像是它们共享同种进化一样。
So some scientists think fluorescent proteins arose really early on in one of the first animal ancestors.
所以一些科学家们认为荧光蛋白早在首批动物祖先中的一只身上出现过。
But if that's the case, it's not clear why it was later lost by so many lineages like our own.
但是如果是这样，那么我们并不清楚为什么后来很多世系，比如人类，都失去了这种蛋白。
Some have even suggested their presence might be explained by multiple events of horizontal gene transfer,
一些人认为它们的存在或许可以通过水平基因转移的多次运动来解释，
a rare phenomenon where a gene jumps from one organism to another.
这是一种稀有的现象—一个基因从一个生物体跳至另一个。
Wherever they came from, these GFPs and other proteins can explain how life fluoresces, but it doesn't really explain why.
不论它们来自哪里，这些GFP和其他蛋白质可以解释生物如何发出荧光，但却不能解释其原因。
It's especially hard for us humans to answer that question because we don't see the world in all its colorful glory.
人类想知道答案尤为困难，因为我们无法看到所有的色彩世界。
We can't see ultraviolet wavelengths, so we don't realize which things stand out to other organisms
我们看不见紫外线波长，所以我们不知道其他生物体会被哪些所吸引
because they're glowing certain colors instead of reflecting UV.
因为它们发出的是某种颜色而非反射紫外。
But, with some help of blacklights, we're starting to see this hidden neon world and we're learning that all sorts of life is rave-ready.
但借助黑光诱虫灯的帮助，我们就可以看见这个隐藏的霓虹灯世界，我们也知道了各种各样的生命都随时准备狂欢。
In many cases, like those pink squirrels,
很多情况下，如粉红色的松鼠，
animals probably use fluorescence the way they would other kinds of coloration, to camouflage themselves, or to communicate.
动物们可能利用荧光伪装自己或用来沟通。
But because fluorescence essentially converts light into different wavelengths, it can do much cooler things.
但是因为荧光会将光线转换成不同的波长，所以荧光可以用来做更酷的事情。
Shallow-water corals, for instance, seem to use fluorescent proteins as a kind of sunscreen for their symbiotic algae—
例如浅水珊瑚将荧光蛋白作为一种保护共生藻类的防晒霜—
they absorb potentially harmful UV rays and emit wavelengths that are less harsh.
它们吸收有害的紫外线并发射出没那么刺眼的波长。
Deep-water corals also fluoresce. They don't have to worry about UV damage, though.
深水珊瑚也能发出荧光。虽然它们根本就不需要担心紫外线的伤害。
Their problem is getting enough light in the first place, see, it's harder for light to move through water than air,
它们的问题是获得充足的光线，因为光线穿过空气很简单，但穿过水面就很难，
so the go further down you go, you lose lower-energy wavelengths like reds and yellows.
所以潜入的越深，就会损失低能量波长，如红色和黄色波长。
Eventually everything starts to look kind of blue. But that blue light doesn't penetrate as deeply into the corals' tissues.
最终一切事物看起来就像是蓝色。但是蓝光不能像渗透珊瑚组织一样深入渗透水中。
So for deeper corals, fluorescing—especially in shades of orange, yellow and red—
所以对于更深处的珊瑚而言，荧光—尤其是在橙色、黄色和红色阴影中—
can help ensure what little light is available reaches their algal partners.
可以帮助确保什么光可以抵达它们的海藻伙伴身上。
And for other creatures that live down in those depths, the ability to fluoresce can add reds and yellows back into their world.
对于那些生活在深处的生物而言，发出荧光的这种能力可以为它们的世界增添红色和黄色。
Some reef fish use these new colors to stand out, while others basically shine them like a special flashlight to reveal hidden prey.
一些岩礁鱼利用这些新颜色突出自己，而其他生物就像一支特殊的手电筒一样照亮那些隐藏的猎物。
But perhaps the coolest fluorescent adaptation is back on land with those scorpions.
但也许最酷的荧光适应还属陆地上的那些蝎子。
Some researchers think their eerie glow helps them sense moonlight so they can avoid predators.
一些研究人员认为它们诡异的光芒能够帮助它们感知月光，这样它们就可以避开捕食者。
Like us, they can't see UV light directly.
和人类一样，它们无法直接看到紫外线。
But, their fluorescent proteins can convert the UV rays from bright moonlight into a color their eyes are more in tune with,
但它们的荧光蛋白可以将来自月光的紫外线转换成它们眼睛能看到的颜色，
letting them see how bright their surroundings are.
让它们看清周围的事物。
They might even be able to sense the blue-green light with nerve cells found all over their bodies,
它们甚至可以用布满全身的神经细胞感知蓝绿色的光，
essentially turning the entire animal into one big moonlight sensor.
将自己变成一个巨大月光感应器。
However animals use their neon glows, one thing is clear: lots of living things fluoresce.
不管动物如何运用它们的霓虹光，有一件事是明确的：很多生物都可以发出荧光。
But that doesn't mean it's always a useful adaptation.
但是这并不表示这总是一种有效的适应。
Basically all plants fluoresce red when they're making food from sunlight, a fact botanists can use to measure how productive they are.
几乎所有植物在从阳光中吸收食物的时候都能发出荧光，植物学家可以利用这一点测试它们的多产性。
But the red glow doesn't necessarily do anything for the plants.
但红光对植物没有任何用处。
Similarly, there are some places fluorescence is found in animals, like in crayfish brains,
同样，动物身上一些地方的荧光，如小龙虾的大脑
where we're not yet sure how or if it's actually helpful.
我们并不确定这些部位的荧光是否以及有何帮助。
It's more than likely some of the brilliant neon glow we see when we light up the world with a blacklight
当我们打开黑光诱虫灯照明的时候，我们看到的一些明亮的霓虹光
is simply a coincidence of the way some molecules are structured.
很有可能只是一些分子构成方式的巧合。
Still, fluorescing just seems to be something life does. And that might be true elsewhere in the universe, too.
似乎只是有生命的物体才发出荧光。在宇宙其他地方也是如此。
In a 2018 paper from the Monthly Notices of the Royal Astronomical Society,
在《皇家天文学会月报》的一篇2018年的论文中，
two scientists argued that the fluorescence of animals like corals
两名科学家称动物，如珊瑚的荧光
could leave a distinct biosignature in the light reflected from a planet during a UV flare.
在紫外线耀斑时，可以在从地球反射出的光线中留下特别的生物标记。
And that means the neon glow of life could reveal whether it's out there somewhere else in the universe. Which is just kind of beautiful.
这意味着生物的霓虹光可以揭示它是否存在于宇宙的其他地方。这有点美丽哟。
In case you haven't noticed, astronomers spend a lot of time examining light from the universe.
你可能没有注意到，天文学家花了大量时间检测来自宇宙的光。
And if you want to understand why that is, you might like the course on Astronomy from Brilliant.org.
如果你想了解这些光，你或许会喜欢Brilliant.org的天文学课程。
It explains the basic toolbox astronomers use to investigate the cosmos, including looking at light.
其中解释了天文学家使用的用于调查宇宙（包括观察光线）的基本工具箱。
And that's just in the first set of quizzes! You can also dive deep into the life cycles of stars, or how we look for habitable worlds.
这只是小测试的第一套！你也可以深入星星的生命圈或是看看人类是如何寻找宜居世界的。
And astronomy is one of the interactive lessons and quizzes in math and science Brilliant offers.
天文学是Brilliant为大家提供的数学和科学交互课程和测试之一。
You can check it and all the others out at Brilliant.org/SciShow.
你可以登陆Brilliant.org/SciShow去看看这门课以及上边的所有其他课程。
Right now, the first 200 people to sign up at that link will get 20% off of an annual premium subscription to Brilliant.
现在头200名使用下方链接注册的用户可以享受年费8折优惠。
And in addition to having a great time and learning about the universe, you'll also be supporting SciShow. So, thank you!
除了能够享受美好时光以及了解宇宙，也是在支持《科学秀》。所以感谢！
