(单词翻译:单击)
Much like birds themselves, bird eggs come in a wide range of colors and patterns.
鸟蛋和鸟一样，有着各式各样的颜色和图案。
And some of those make sense. Like brown or mottled eggs, because, you know, camouflage.
其中一些很正常，比如棕色或杂色蛋，这是为了伪装。
But some birds lay bright blue eggs, which just seems weird.
但一些鸟会产下鲜蓝色的蛋，这就有些奇怪了。
I mean, they aren't being laid in blue nests or in a bed of blue flowers or anything.
我是说，这些蛋不是被下在蓝色的鸟巢中，也不是被下在蓝色花海中。
There simply isn't an obvious explanation for that color.
对于这种颜色，根本没有一个明显的解释。
But biologists have given this a lot of thought over the years, and thanks to some clever experiments,
但多年来，生物学家对此进行了很多思考，并且多亏了一些巧妙的实验，
we're finally starting to understand why birds might benefit from conspicuously colored eggs.
我们最终开始理解为什么鸟儿们或许能从鲜艳色彩的鸟蛋中获益了。
There are hundreds of bird species that lay blue to blue-green eggs.
有数百种鸟类会下蓝色或蓝绿色的蛋。
They get those hues thanks to a pigment called biliverdin that's deposited into the eggshell while the egg is developing.
这种颜色的蛋要归因于一种叫做胆绿素的色素，这种色素是在蛋发育时期沉淀在蛋壳中的。
But while we understand how they become blue, exactly why has proven a bit tougher to pin down.
但虽然我们知道它们是如何变成蓝色的，但确切的原因却很难确定。
Ornithologists are still debating a few main hypotheses.
鸟类学家仍在争论一些主要的假设。
Some think the eggs are a signal of mate quality, and specifically, the quality of the female who laid them.
一些鸟类学家人为蛋是配偶质量的一个信号，尤其是产下鸟蛋的雌性的质量。
That tracks logically, since studies have found that females who lay biliverdin-rich eggshells are in better shape.
这符合逻辑，因为研究发现，产下富含胆绿素蛋壳的雌性更健康。
So bluer eggs may indicate a higher quality partner, one who's worth investing in. And field experiments support this.
所以蛋越蓝或许意味着这个伴侣质量更高，是值得投入的。野外试验证实了这一点。
For instance, when researchers swapped around pied flycatcher eggs, they found that males delivered more food if their mates were incubating bluer eggs.
例如，当研究人员调换了彩衣蝇蛆的卵后，他们发现雌性孵化的卵更蓝，雄性就会带回更多的食物。
And studies on gray catbirds and American robins have found that males provide more care to chicks from colorful clutches,
对灰猫嘲鸫和旅鸫的研究发现，雄性会给彩蛋孵出的后代更多照顾，
all of which seems to support the idea that egg color may signal a worthy investment. But there is an alternative explanation.
这一切似乎支持了这样一个观点：蛋的颜色或许表明它值得投资。但还有另一种解释。
Some evidence suggests that the extra effort is actually an attempt to protect the eggs, an idea cheekily described as the blackmail hypothesis.
一些证据表明这种额外的努力其实是为了保护鸟蛋，这种想法被描述为胁迫假说。
Essentially: it's easier to see brighter eggs, so nests that contain them are at a higher risk of being targeted by predators and parasites
本质上：颜色更亮的蛋更容易被发现，所以有这种蛋的鸟巢被捕猎者和寄生生物袭击的风险更高
whenever the female has to leave, like, to go catch food.
比如在雌性离开捕食的时候。
And that might put pressure on males to pull a little more weight around the nest,
这可能给雄性带来压力，让雄性将更多注意力放在鸟巢周围，
thereby reducing the overall time the eggs are left alone.
因此减少了鸟蛋独处的时间。
The thing is, not all studies agree that dad birds put more effort in when eggs are bluer.
但问题是，并不是所有研究都认为，当鸟蛋更蓝的时候，雄性会付出更多努力。
So some have proposed that blueness has little to nothing to do with males, and everything to do with the sun.
所以一些认为蓝色度和雄性没什么关系，并且这一切都和太阳相关。
This hypothesis posits that the color provides protection from damaging UV radiation that can penetrate through the eggshell.
这种假设认为，颜色可以保护蛋壳免受紫外线辐射的伤害，因为紫外线可以穿透蛋壳。
While some birds lay eggs in cavities like in old dead trees, many nests are in more open areas.
虽然一些鸟类会将鸟蛋下在像枯老的树木中的鸟巢内，但很多鸟巢被建在更加空旷的区域。
And the eggs in such nests may be exposed to intense sun whenever a parent isn't sitting on them.
当父母没有坐在蛋上时，这种鸟巢中的鸟蛋可能会暴露与强烈的阳光下。
So, in those cases, extra blue pigment in the shell could help filter out some of the high-energy light, kind of like sunscreen.
所以在这类情况中，蛋壳中额外的蓝色色素可以帮助滤出高能光，就像防晒霜一样。
And that seemed to be the case in one study on village weaverbirds, but there was a catch.
在对于一种黑头织布鸟的研究中，情况似乎如此，但有一处疑点。
More intense blueness also increased the infrared radiation the eggs absorbed. So, the eggs got warmer.
更深的蓝色也增加了鸟蛋吸收的红外线，所以鸟蛋会更加暖和。
That would suggest the need to strike a balance, not too much blue, but not too little, depending on the nest's location and lighting.
这表明需要维持一种平衡，蓝色不能太多，也不能太少，这取决于鸟巢的位置和光线。
And we're still trying to determine all the variables at play when it comes to blue eggs.
我们仍在试图弄清楚影响蓝色鸟蛋的所有变量。
Studies have suggested other potential benefits, like, that biliverdin itself may actually strengthen shells.
研究已经表明了其他潜在益处，比如胆绿素本身可以强化蛋壳。
So while signaling female quality, blackmailing males, and sunscreen are the big ideas floating around,
虽然传达雌性品质、胁迫雄性以及防晒等主要想法流传，
there seems to be a number of surprising upsides to blue eggs, which ultimately helps explain why so many species have evolved cerulean shells.
但蓝色鸟蛋似乎有着更多意想不到的益处，这最终能帮助解释为什么这么多物种都进化出了蓝色蛋壳。
Thanks for asking! And thanks for watching SciShow.
感谢提问，也感谢收看本期节目。
If you enjoyed learning about the evolution of blue eggs, I bet you'll enjoy our episode on mind-blowing birds nests.
如果你想学习更多关于蓝色鸟蛋进化的知识，我猜你一定也会喜欢我们关于令人震惊的鸟类巢穴的那期节目。
And you also might consider clicking that subscribe button, if you haven't already,
如果你也考虑点击订阅按钮，
we put out new episodes covering awesome science like this every day!
我们每天都会有关于神奇科学的视频奉上！
And if you subscribe, you get all of them delivered straight to your YouTube feed.
如果你订阅了，所有的视频都会直接传到你的YouTube上。
