Can you guess what you're looking at?

你能猜到這是什麼嗎？

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

若你回答「鴨子陰道」，那你就對了

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

雖然鴨子的外貌或許不算奇特

it uses this strange, intricate,

卻是透過這奇異、複雜

cork-screw shaped contraption to reproduce.

螺旋型的裝置來繁衍

We see similarly unbelievable genitalia in insects,

類似的奇特生殖器同樣存在於昆蟲

mammals,

哺乳類

reptiles,

爬蟲類

fish,

魚

spiders,

蜘蛛

and even snails.

甚至是蝸牛

Apparently, no organs evolve faster and into more variable shapes

很顯然比起其他器官，生殖器官演進速度更快

than those involved in procreation.

構造也更多變

Superficially, it makes sense because evolution works via reproduction.

表面看來這不難理解，畢竟演化就是透過生殖進行

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

當一種動物擁有更多後代，基因也隨著傳撥出去

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

而既然生殖器是動物賴以繁衍的工具

any improvement there will have immediate effect.

任何相關的改進都會立即產生效果

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

然而，有著如此花俏的下半身有何用意？

After all, the function of genitalia seems simple.

畢竟生殖器的運作很單純

A penis deposits a bit of sperm

陰莖釋出一些精子

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

陰道接收精子，使卵受精

A pipette-like thingy on the male

雄性擁有滴管型的物體

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

雌性擁有漏斗型的構造，這樣對任何動物而言照樣能生殖

And yet, that's not what we see.

但情況並非如此

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

舉例來說，雞蚤的陰莖一點也不像滴管

more like an exploded grandfather clock.

比較像是爆掉的老爺鐘

And the vagina of a featherwing beetle

而一隻羽翅甲蟲的陰道

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

則形似你在蘇斯博士書裡可能會看到的東西

Throughout the animal kingdom,

在動物世界裡

genitalia are very complex things,

生殖器是很複雜的東西

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

比起單單為了繁殖還要繁瑣許多

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

那是因為生殖器的功用遠多於只是保存精子還有受精

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

許多雄性動物使用牠們的陰莖來求偶，比如大蚊

In some South American species,

某些南美品種的公大蚊

males have a tiny washboard and scraper on their penis,

在陰莖上有迷你洗衣板和刮具

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

透過交配在母大蚊的體內

when they mate.

迴響一首樂曲

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

人們猜想要是母大蚊喜歡這首奇特的小夜曲

they'll allow the male to father their offspring.

就會允許公大蚊與牠們繁殖

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

這樣看來，保有最具音樂性陰莖的基因得以延續

leading to rapid evolution of insects' phalluses.

使得昆蟲陰莖迅速演化

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

類似的還有某些甲蟲在陰莖的兩側會有小鼓槌

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

在交配過程，它們會摩擦、拍打、或是敲打母甲蟲

And some hoofed mammals, like rams and bulls,

還有一些有蹄哺乳類動物，像是公羊和公牛

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

會運用陰莖左側形似鞭子的延伸物

to create a sensation during mating.

帶來交配過程的愉悅感

But how can females really choose between males

但雌性在交配後才能評估

if she can only assess them after mating?

又該如何在眾多雄性間做出抉擇？

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

這就是雌性擇偶能力浮出檯面的時候

In fact, insemination is different to conception,

事實上，接了精子並不等於受精

and the female genitalia exploit this distinction.

雌性生殖器活用了這個差異性

For instance, in some dung flies,

比如有些糞蠅的陰道

the vagina contains pockets for separating sperm from different males

設置有口袋可以分放來自不同雄性的精子

depending on how appealing they were.

這全取決於不同的精子有何優勢

Males using their penises for courtship

雄性運用陰莖求偶

and females controlling their own sperm management

雌性調控管理精子

are two reasons why genitalia evolve into such complex shapes.

這是為何生殖器演變成複雜形狀的兩個原因

But there are others

但還有其他因素

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

因為生殖器也是交配抗爭上演的地方

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

對於雌性來說，用來源最好的精子使卵受精

with the sperm of the best fathers

是最好的結果

and creates genetic variability amongst her offspring.

並能使後代保有基因多樣性

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

這對於雄性來說卻是個壞消息

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

對雄性而言，最好的情況是牠所有的精子

to fertilize all of her eggs.

皆被拿來使卵受精

So we see cycles of adaptation in an evolutionary arms race

我們因而看到在自然選擇淘汰下

to retain control.

多方爭奪主控權

Black widow spiders have a disposable penis tip

黑寡婦蜘蛛拋棄式的陰莖頭部

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

會斷裂在陰道內，擋住對手精子前進的道路

and bed bug males bypass a female's genitalia altogether

公床蝨則透過像注射器的陰莖

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

繞過母床蝨的生殖器，將精子直接注入腹腔

Not to be outdone,

不輕易任人擺佈

females have evolved their own countermeasures.

母床蝨演變出一套對策

In some bed bug species,

在某些品種的床蝨

the females have evolved an entirely new set of genitalia

雌性演化出一套全新的生殖器

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

位於公床蝨通常會刺穿的右腹部

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

讓她們保有透過生殖器篩選精子

with their genitalia.

的能力

And duck vaginas are shaped like a clockwise spiral

鴨子的陰道則是順時針的螺旋狀

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

所以當公鴨挺入逆時針的捲曲長陰莖時

and she disapproves,

母鴨能夠抵抗

all she needs to do is flex her vaginal muscles

只需彎曲牠的陰道肌

and the penis just flubs out.

陰莖就沒搞頭了

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

生殖器之所以型式多變，並非為了驚豔他人

but because in every species,

而是因為在各種物種中

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

這些生殖器是透過如此激烈的演化過程而來

that has been going on for millions of years

演化歷經了數百萬年

and will continue for millions of years to come.

未來也將持續下去