The evolution of animal genitalia - Menno Schilthuizen

翻译人员: Ying Lu 校对人员: Coco Shen

The evolutionary tango of animal genitalia.

动物生殖器的进化探戈之舞

Can you guess what you're looking at?

你能猜猜你看到的是什么吗？

If you answered "duck vagina," you'd be right.

如果你回答“鸭子的阴道“， 那么你答对了。

Although the bird's outward appearance may not strike you as especially odd,

尽管从外表看，这只鸟极其普通。

it uses this strange, intricate,

但是内部使用着 既神奇又错综复杂的

cork-screw shaped contraption to reproduce.

形似螺旋拔塞器的奇妙器官来繁殖。

我们在下列动物身上同样看到了相似的神奇的 生殖器官，例如昆虫、

We see similarly unbelievable genitalia in insects,

mammals,

哺乳动物、

爬行动物、

reptiles,

fish,

鱼、

spiders,

蜘蛛、

and even snails.

甚至蜗牛。

Apparently, no organs evolve faster and into more variable shapes

很显然，没有任何器官 能比生殖器

进化得更迅速和多样化的了。

than those involved in procreation.

Superficially, it makes sense because evolution works via reproduction.

乍看之下，因为进化是通过繁殖产生， 因此生殖器进化快是颇有道理。

When an animal leaves more offspring, its genes will spread.

当动物繁殖出更多后代时， 就意味着它们的基因得到传播。

And since genitalia are an animal's tools for reproduction,

由于动物用生殖器官来繁殖，

any improvement there will have immediate effect.

任何生殖器的进化将产生立竿见影的效应。

And yet, what's the point of having such decorative nether regions?

但是为什么需要这些看上去 很像装饰品的器官呢？

After all, the function of genitalia seems simple.

毕竟，生殖器的功能还是很简单的。

A penis deposits a bit of sperm

阴茎储存着精子，

and a vagina receives it and delivers it to the egg.

阴道接收精子后输送到卵子。

雄性吸管形状的性器官

A pipette-like thingy on the male

and a funnel-like gizmo on the female should do just fine for any animal.

和雌性像漏斗一样的阴道让彼此十分融洽。

And yet, that's not what we see.

但是，事实并非我们所想。

The penis of a chicken flea, for example, looks nothing like a pipette,

例如，雄性鸡跳蚤的生殖器一点也不像吸管，

more like an exploded grandfather clock.

它更像一个爆炸了的落地大摆钟。

羽翅虫（鞘翅目的一种）的阴道

And the vagina of a featherwing beetle

resembles something you'd find in a Dr. Seuss book.

会让你联想到Seuss博士书中的事物。

Throughout the animal kingdom,

在整个动物王国，

genitalia are very complex things,

生殖器是一个非常复杂的器官，

much more complicated than seems necessary for what they're meant to do.

其复杂程度远超于它们所该有的作用。

其实生殖器除了储存和接收精子 还有其它的作用。

That's because genitalia do more than just deposit and receive sperm.

Many male animals also use the penis as courtship device, like crane flies.

许多雄性动物使用生殖器作为求爱工具 例如大蚊盲蛛。

In some South American species,

在一些南美州生物物种中，

males have a tiny washboard and scraper on their penis,

雄性生殖器上长有搓衣板和刮板的花纹，

which produces a song that reverberates throughout the female's body

当它们交配时，将会产生一首美妙的乐曲

when they mate.

并在雌性体内回响。

It's thought that if female crane flies enjoy this unusual serenade,

如果雌性大蚊盲蛛享受 这首非同寻常的小夜曲，

they'll allow the male to father their offspring.

它们将为这个雄性大蚊盲蛛繁衍后代。

This way, the genes of the most musical penises spread,

因此，最富有音乐性的雄性生殖器基因 得到了传播，

leading to rapid evolution of insects' phalluses.

并紧接着促进昆虫生殖器的快速进化。

Similarly, some beetles have two little drumsticks on either side of the penis.

同样的，在一些昆虫的阴茎两边长有“鼓棒”。

During mating, they'll rub, slap, or tap the female with these.

在交配时，它们使用“鼓棒”来摩擦、拍击或者轻敲着雌性。

And some hoofed mammals, like rams and bulls,

一些长有蹄子的哺乳动物，例如公羊和公牛，

use a whip-like extension on the penis's left side

使用阴茎左边像鞭子一样的延长物

to create a sensation during mating.

在交配时创造一种感觉。

But how can females really choose between males

但是雌性如何在不同雄性中做出选择

if she can only assess them after mating?

如果仅仅根据和它们交配后的感觉？

This is where the power of female adaptation comes into play.

这就正是雌性进化中的权利所在。

In fact, insemination is different to conception,

事实上，人工授精是另一个概念。

and the female genitalia exploit this distinction.

雌性的阴道正是利用了这个差别。

For instance, in some dung flies,

例如，在一些粪蝇中，

the vagina contains pockets for separating sperm from different males

它们的阴道含有储存不同雄性精子的口袋

depending on how appealing they were.

这取决于雄性的魅力指数。

Males using their penises for courtship

雄性使用生殖器来求偶

and females controlling their own sperm management

和雌性使用阴道来控制精子

are two reasons why genitalia evolve into such complex shapes.

是为什么生殖器进化得如此复杂的两个原因。

But there are others

除此之外，

because genitalia are also where a sexual conflict is played out.

生殖器也是两性冲突的发源地。

A female's interests are best served if she fertilizes her eggs

能让雌性心满意足的就是为自己的卵子

找到了最好的雄性精子

with the sperm of the best fathers

and creates genetic variability amongst her offspring.

并在她的后代中产生基因变异。

For a male, on the other hand, this is bad news.

但是对于雄性来说，这是一个噩耗。

For him, it would be best if a female used his sperm

与他而言，雌性最好的选择就是用他的精子

to fertilize all of her eggs.

来授精她所有的卵子。

这也是为什么在生物进化的军备竞赛中

So we see cycles of adaptation in an evolutionary arms race

to retain control.

有所保留。

Black widow spiders have a disposable penis tip

雄性黑寡妇蜘蛛有一个一次性的阴茎尖物，

that breaks off inside the vagina blocking the attempts of his rivals,

这个尖物会在阴道中折断 以阻止其他竞争者精子的进入。

雄性臭虫则会绕过雌性的阴道，

and bed bug males bypass a female's genitalia altogether

using a syringe-like penis to inject sperm cells directly into her belly.

用它们像注射器一样的阴茎将精子 直接注入雌性的肚子。

Not to be outdone,

不甘人后的是，

females have evolved their own countermeasures.

雌性也进化出了对策。

在一些臭虫种类中，

In some bed bug species,

the females have evolved an entirely new set of genitalia

雌性进化出了一个全新的生殖器

长在她们经常被雄性插入的右侧腹。

on their right hand flanks where the males usually pierce them.

That allows them to maintain the power to filter out unwanted sperm

这样雌性就能通过生殖器来保留筛除

不想要的精子的权利。

with their genitalia.

And duck vaginas are shaped like a clockwise spiral

雌性鸭子的阴道形似顺时钟的螺旋，

so that when the male inflates his long, counterclockwise coiled penis into her,

因此当雌性要拒绝膨胀着逆时钟旋转生殖器的雄性时，

and she disapproves,

all she needs to do is flex her vaginal muscles

她需要做的仅仅是收缩阴道肌肉，

and the penis just flubs out.

雄性的阴茎也就没戏了。

因此，生殖器是各种各样。 它不仅仅让我们着迷，

So, genitalia differs so much, not just to fascinate us,

but because in every species,

在不同生物种类中，

they're the result of a furious evolutionary tango of sex

它们是一支狂热的性爱进化探戈之舞。

that has been going on for millions of years

不仅存在于过去的几百万年，

and will continue for millions of years to come.

更会在接下来的时间中继续进化。