外星世界（2020）

一个重要因素
in the evolution of life.
捕食无所不在
Predation is everywhere.
所有生物都有
There's not an organism out there
被另一种生物吃掉的风险
that doesn't run the risk of being eaten by another organism.
我感兴趣的方面在于 捕食如何影响繁殖
The aspect that I'm interested inxa0 is how predation shapes reproduction.
（特立尼达 阿里马谷）
它们会到这里来
They're gonna be comin' in here.
这条河流非常适合研究孔雀鱼
This river is perfect for studying guppy fish. . .
以及它们繁殖的模式
and their patterns of reproduction.
-是 -另一条雄鱼
Here. Here's another male. Yeah, yeah.
这里的环境很友好
This is an easy neighborhood.
孔雀鱼只和另一个鱼的物种 在这里生存
Here, guppies live with only one other species of fish,
这种鱼很少会吃孔雀鱼 或者骚扰它们
and it's a fish that rarely eats guppiesxa0 or harasses guppies.
孔雀鱼可以游到任何地方 而不用担心被吃掉
They can swim wherever they want without any risk of somebody trying to eat them.
-好 抓到了 -抓到了
Oh, right. There you go. All right. Here we go.
我们捕到一些孔雀鱼 我们这里有五条
Here we have some babies thatxa0 we just caught. We have five of them here.
你也许觉得它们很小 但作为新诞生的孔雀鱼
They may look small to you, but that's really big
它们已经很大了
for a newborn baby guppy.
这里的孔雀鱼把大量的精力 投入在相对较少的后代身上
The guppies here invest a lot of effort in relatively few offspring.
而在下游 情况就完全不同了
Downstream, it's a different story.
好了
Okay!
哇
Wow.
这块巨石是个自然屏障 把河流分成两部分
This boulder is a natural barrier, dividing the river.
在这之下 潜伏着危险
Below it lurks danger.
孔雀鱼在这里的生活 差不多是一种逃亡生活
A guppy life down here is pretty much like the life of a fugitive.
你随时都在逃避捕食者 如果一条孔雀鱼在这里游
You're always on the run from predators. If a guppy were to swim out here. . .
它的生命不能延续多久
it wouldn't last a second.
孔雀鱼唯一的防御手段 就是繁殖很多后代
The only defense the guppies have is to produce lots of offspring,
以期待一部分能活到成年
in the hope that some will survivexa0 to adulthood.
好了 我这里有两条来自上游的幼鱼 那里没有捕食者
Okay, I've two babies from up there, xa0 where guppies live without predators,
还有四条来自下游的 这里有捕食者
and four from down here, where guppies live with predators.
它们个头的差别非常大
There's a dramatic difference in size.
这里幼鱼的个头
Those that are from here are much, much smaller
要比来自屏障上游的小很多
than the ones that I caughtxa0 above the barrier.
无论母鱼怎么做 她们活到未来的机会都不大
Moms don't have a big prospect of living to the future, no matter what they do.
所以在这里最佳的策略就是 繁殖很多个头小的幼鱼
So the best strategy down here is to make many small babies.
孔雀鱼进化出两种不同的繁殖方式
The guppies have evolved two different ways of breeding.
产出为数不多的大个头的幼鱼…
Having a few large babies. . .
或产出很多小个头的幼鱼
or lots of small ones.
决定因素在于捕食者的威胁
The deciding factor is the threat from predators.
如果你会成为猎物 你活不了很久
If you're one of the prey items, xa0 you're gonna die young,
那你最好活得快一些
so you better live fast.
你最好努力繁衍后代 否则你就会灭绝
You better put a lot into having babies, because if you don't, you'll go extinct.
这种策略适用于任何星球
Such a strategy would apply on any planet
只要那里有一个物种捕食另一个物种
wherever one species preys on another.
在伊甸 食草动物通过进化 繁殖变得很快
On Eden, the grazers have evolvedxa0 to breed fast.
它们尽快产出尽量多的后代
They produce as many offspringxa0 as quickly as possible. . .
以确保物种能够延续
to ensure the survival of the species.
但在丛林里 它们没有真正的安全
But in the forest, xa0 they're never truly safe.
随着夏天的结束
As summer ends,
菌类长出橘红色的果实
the fungi grow orange-colored fruit. . .
这会吸引食草动物
which attract grazers.
果实里的孢子会散播感染
Spores within the fruit spread an infection.
现在 掠食者攻击时
Now, when predators attack,
受感染的食草动物不会跑
infected grazers don't run.
它们已经失去了害怕的本能
They've lost their fear instinct.
这顿食物来得很轻松
It's an easy meal. . .
但却是有毒的
but a poisonous one.
菌类利用了食草动物 感染并杀死了掠食者
The fungi have used the grazersxa0 to infect and kill the predators.
（坦桑尼亚 大裂谷）
这种复杂的关系 在地球的物种之间也存在
Such complex relationshipsxa0 between species exist on Earth. . .
但并不都是致命的
but not all are so lethal.
哈扎人过着原始生活 靠土地过活
The Hadza are hunter-gatherers, living off the land.
我叫帕兰戈
My name is Palango.
作为一个男人 我的职责是狩猎
As a man, my job is to hunt.
我总是带着弓和箭
I always carry a bow and arrow
作为保护
for protection. . .
因为树丛里
because the bush
有很多危险的动物
has many dangerous animals.
有一种高卡路里的食物备受推崇
One high-calorie food is prizedxa0 above all else.
它就是蜂蜜
Honey.
但是寻找新鲜蜂蜜非常困难
But finding fresh honey is difficult.
每次换季 蜜蜂会在不同的地方筑巢
The bees move their nestsxa0 from season to season.
于是 哈扎人找来帮忙的
So the Hadza call on help.
响蜜鴷是一种非常聪明的鸟
Honeyguides are very clever birds.
它们知道蜂蜜在哪儿 并会带你去
They know where honey is, and they will take you there.
它会发出一种特别的叫声…
She makes a special cry. . .
而我吹口哨回应
. . . and I whistle back.
只要我跟着它 它会把我直接带到有蜂蜜的地方
If I follow her, she will lead me directly to the honey.
响蜜鴷果然名不虚传
The honeyguide has lived up to its name.
把狩猎者带到一棵猴面包树上的蜂巢
It's led them to a bees' nestxa0 in a baobab tree.
狩猎者需要这种鸟来找到蜜蜂
The hunters need the birdxa0 to find the bees.
响蜜鴷需要狩猎者来获取蜂蜜
And the bird needs the huntersxa0 to access the honey.
响蜜鴷带我们找到蜜蜂
The honeyguides take us to the bees.
但蜜蜂具有进攻性
But the bees are aggressive.
所以 它需要我们的帮助
So she needs our help.
爬上猴面包树
Climbing up a baobab tree. . .
非常困难 也非常危险
is very hard and dangerous.
有一次我摔了下来
One day I fell.
我们用烟把蜜蜂熏晕
We use smoke to get the bees drunk
把它们赶出蜂巢
and chase them out of the nest.
风险是值得的
The risk is worth it.
新鲜浓烈的蜂蜜
Fresh, rich, honey.
帕兰戈给了鸟它该得的一份
Palango makes sure the bird gets its share.
这是双赢
It's a win-win situation.
物种之间建立的一种 被称为共生的复杂的关系
A complex relationship between species is known as symbiosis.
生态系统越是丰富 关系就越复杂
The richer the ecosystem, the more complex the relationship.
在伊甸 一种致命的三向共生关系演化出来
On Eden, a deadly three-way symbiosisxa0 has evolved. . .
核心是菌类
centered around the fungi.
首先 它们让食草动物吃
First, they feed the grazers.
让它们受到感染
Then, they infect them. . .
再去毒死掠食者
to poison the predators.
菌类这样做的目的 是为了它们下一代的成长
And the fungi do all this to grow their next generation. . .
它们下一代从掠食者的尸体得到营养
which feeds on the bodiesxa0 of the dead predators.
在地球上 菌类对森林的生机 起着关键但看不见的作用
On Earth, xa0fungi play a crucial, but invisible role in the life of any forest,
在幕后
behind the scenes.
（苏格兰 罗希姆丘奇森林）
我觉得绝大部分人以为 我们星球上首先出现的复杂生命
So, I think most people think the first complex life on our planet
是诸如昆虫 甚至也许是恐龙
was something like insects, or maybe even the dinosaurs.
但事实上 比这早数万亿年
But, actually, xa0 hundreds of millions of years before that,
第一种真正的复杂的 多细胞生物是这些东西
really the first complexxa0 multicellular organisms were these things.
菌类
Fungi.
我们已知至少有14万个物种
We know of at least 140, 000 species,
但这可能不到真正总数的百分之十
but that's likely to be less than ten percent of the real total.
仅仅在这个森林里 也许就有数千种
There's probably thousandsxa0 of different fungal species
不同的菌类物种
just in this forest alone.
好 我们这里有三个蘑菇
Okay, so we've actually got three mushrooms here
你能看到这种蘑菇分布在整个森林里
and you can actually see these dottedxa0 all throughout the forest.
但神奇的是
But what's amazing is that these mushrooms
你看到的这些蘑菇只是冰山一角
are really just the tip of the iceberg.
当我们揭开地层表面
When we look below the surface,
绝大部分的菌类是这些
most of the fungus is actuallyxa0 in these little. . . tiny little threads,
遍布在土壤里的细丝
that go all throughout the soil.
这种东西称为菌丝体
And this is called the mycelium,
它连接着这个地区所有的蘑菇
and it connects all of the other mushrooms in this area.
这种遍布于土壤中的微小的菌类
There can be tens of kilometersxa0 of these tiny microscopic fungi
蔓延数十公里
spreading throughout the entire soil.
树木的生存依赖于这些纤维
The tree needs those fibers to survive,
因为树木能从大气里获取碳元素
because the tree can capturexa0 carbon from the atmosphere,
为菌类提供碳元素
and it provides that carbon to the fungus.
同时 菌类能从土壤中获取氮和磷
In contrast, the fungi accessxa0 nitrogen and phosphorus from the soil,
以交换碳元素