Billions of years ago on the young planet Earth simple organic compounds assembled into more complex coalitions that could grow and reproduce.
数十亿年前，在年轻的地球上，简单的有机化合物聚集成更复杂的结合，可以生长和繁殖。
They were the very first life on Earth,
他们是地球上第一代生命，
and they gave rise to every one of the billions of species that have inhabited our planet since.
他们创造了数十亿物种中的每一个，这些物种从那时起就一直居住在我们的星球上。
At the time,
当时，
Earth was almost completely devoid of what we"d recognize as a suitable environment for living things.
地球几乎完全没有我们认为适合生物生存的环境。
The young planet had widespread volcanic activity and an atmosphere that created hostile conditions.
这个年轻的星球有着广泛的火山活动和形成敌对条件的大气层。
So where on Earth could life begin?
那么生命从哪里开始呢？
To begin the search for the cradle of life,
开始寻找生命的摇篮，
it"s important to first understand the basic necessities for any life form.
首先了解任何生活形式的基本必需品是很重要的。
Elements and compounds essential to life include hydrogen, methane, nitrogen, carbon dioxide, phosphates, and ammonia.
生命所必需的元素和化合物包括氢、甲烷、氮、二氧化碳、磷酸盐和氨。
In order for these ingredients to comingle and react with each other,
为了让这些成分相互作用，
they need a liquid solvent: water.
他们需要液体溶剂：水。
And in order to grow and reproduce,
为了生长和繁殖，
all life needs a source of energy.
所有的生命都需要一种能量。
Life forms are divided into two camps: autotrophs, like plants,
生命形式分为两个阵营：自养动物，就像植物一样，
that generate their own energy, and heterotrophs, like animals,
产生自己的能量和异养生物，就像动物，
that consume other organisms for energy.
消耗其他生物来获取能量。
The first life form wouldn"t have had other organisms to consume, of course,
当然，第一种生命形式没有其他有机物可以食用，
so it must have been an autotroph,
所以那一定是自养，
generating energy either from the sun or from chemical gradients.
从太阳或化学梯度产生能量。
So what locations meet these criteria?
那么，哪些地点符合这些标准呢？
Places on land or close to the surface of the ocean have the advantage of access to sunlight.
陆地上或靠近海洋表面的地方有获得阳光的优势。
But at the time when life began,
但当生命开始的时候，
the UV radiation on Earth"s surface was likely too harsh for life to survive there.
地球表面的紫外线辐射可能过于严酷，生命无法在那里生存。
One setting offers protection from this radiation and an alternative energy source: the hydrothermal vents that wind across the ocean floor,
其中一种环境提供了免受辐射和替代能源的保护：风吹过洋底的热液喷口，
covered by kilometers of seawater and bathed in complete darkness.
被数公里的海水覆盖，沐浴在黑暗中。
A hydrothermal vent is a fissure in the Earth"s crust where seawater seeps into magma chambers and is ejected back out at high temperatures,
热液喷口是地壳中的一个裂缝，海水在那里渗入岩浆腔，在高温下被喷出，
along with a rich slurry of minerals and simple chemical compounds.
还有丰富的矿浆和简单的化合物。
Energy is particularly concentrated at the steep chemical gradients of hydrothermal vents.
能量特别集中在热液喷口的陡峭的化学梯度上。
There"s another line of evidence that points to hydrothermal vents: the Last Universal Common Ancestor of life,
还有另一条指向热液喷口的证据：生命的最后一个共同祖先，
or LUCA for short.
或者简称卢卡。
LUCA wasn"t the first life form,
卢卡不是第一种生命形式
but it"s as far back as we can trace.
但这是我们能追踪到的最遥远的地方。
Even so, we don"t actually know what LUCA looked like— there"s no LUCA fossil,
即使如此，我们也不知道卢卡长什么样-没有卢卡化石，
no modern-day LUCA still around— instead,
现在卢卡已经不在了，
scientists identified genes that are commonly found in species across all three domains of life that exist today.
科学家们发现了目前存在于所有三个生命领域的物种中普遍存在的基因。
Since these genes are shared across species and domains,
由于这些基因是在物种和区域之间共享的，
they must have been inherited from a common ancestor.
他们一定是从一个共同的祖先继承下来的。
These shared genes tell us that LUCA lived in a hot,
这些共同的基因告诉我们卢卡生活在炎热的环境中，
oxygen-free place and harvested energy from a chemical gradient— like the ones at hydrothermal vents.
无氧的地方，从化学梯度中收集能量-就像热液喷口的能量一样。
There are two kinds of hydrothermal vent: black smokers and white smokers.
有两种热液喷口：黑烟和白烟。
Black smokers release acidic, carbon-dioxide-rich water,
黑烟释放酸性的富含二氧化碳的水，
heated to hundreds of degrees Celsius and packed with sulphur, iron, copper,
加热到几百摄氏度，里面装满了硫，铁，铜，
and other metals essential to life.
以及其他对生命至关重要的金属。
But scientists now believe that black smokers were too hot for LUCA— so now the top candidates for the cradle of life are white smokers.
但科学家们现在认为，黑烟者对卢卡来说太热了，所以现在生活中最受欢迎的候选人是白烟。
Among the white smokers,
在白烟中，
a field of hydrothermal vents on the Mid-Atlantic Ridge called Lost City has become the most favored candidate for the cradle of life.
大西洋中脊上的一个热液喷口被称为“迷失之城”，它已成为生命摇篮中最受欢迎的候选之地。
The seawater expelled here is highly alkaline and lacks carbon dioxide,
这里排出的海水是高度碱性的，缺乏二氧化碳，
but is rich in methane and offers more hospitable temperatures.
但它含有丰富的甲烷并提供了更适宜的温度。
Adjacent black smokers may have contributed the carbon dioxide necessary for life to evolve at Lost City,
邻近的黑人烟民可能为失落之城的生命进化贡献了必要的二氧化碳，
giving it all the components to support the first organisms that radiated into the incredible diversity of life on Earth today.
给予它所有的成分来支持第一批辐射到地球上令人难以置信的生命多样性的生物体。
