Marcus Byrne: The dance of the dung beetle

Translator: Joseph Geni Reviewer: Morton Bast

譯者: Joan Liu 審譯者: Josephine Yeung

This is poo,

這是便便，

and what I want to do today is share my passion

我今天想要做的是與你們分享

for poo with you,

我對便便的熱愛。

which might be quite difficult,

這可能是很困難的

but I think what you might find more fascinating

但我想你們會發現

is the way these small animals deal with poo.

這些小動物處理便便的方式是非常迷人的。

So this animal here has got a brain

這動物的腦大小

about the size of a grain of rice, and yet it can do things

只有米一般大，但仍然可以做一些

that you and I couldn't possibly entertain the idea of doing.

你我想都不會想的事情。

And basically it's all evolved to handle its food source,

基本上這都是由食物源而來的，

which is dung.

也就是糞。

So the question is, where do we start this story?

所以，問題是我們該從哪裡說起呢？

And it seems appropriate to start at the end,

看來，從末端談起適合適的。

because this is a waste product that comes out

因為這是一種出自其它動物的廢物，

of other animals, but it still contains nutrients

但是仍然含有營養素，

and there are sufficient nutrients in there

且所含的養分足以讓

for dung beetles basically to make a living,

糞甲蟲生存。

and so dung beetles eat dung, and their larvae

所以糞甲蟲吃糞便，

are also dung-feeders.

它們的幼蟲也是食糞的。

They are grown completely in a ball of dung.

他們整個生長過程都在糞便中完成。

Within South Africa, we've got about 800 species of dung beetles,

在南非，我們有約 800 種糞甲蟲，

in Africa we've got 2,000 species of dung beetles,

在非洲有 2000 種類的糞甲蟲，

and in the world we have about 6,000 species of dung beetles.

而在全球，有約 6000 種糞甲蟲。

So, according to dung beetles, dung is pretty good.

對糞甲蟲來說，糞便是很好的。

Unless you're prepared to get dung under your fingernails

除非你準備好讓糞便進到你的指甲下

and root through the dung itself, you'll never see

和根本的探究糞便本身，

90 percent of the dung beetle species,

你永遠看不到90%的糞甲蟲物種。

because they go directly into the dung,

因為他們直接進到糞便深處，

straight down below it, and then they shuttle back and forth

然後他們來回穿梭於

between the dung at the soil surface

在土壤表面的糞便

and a nest they make underground.

和他們在地下的巢。

So the question is, how do they deal with this material?

所以，他們是如何利用這樣的材料呢？

And most dung beetles actually wrap it into a package of some sort.

大多數糞甲蟲將其包裝。

Ten percent of the species actually make a ball,

10%的物種包成球狀，

and this ball they roll away from the dung source,

並將這些球滾離糞源，

usually bury it at a remote place away from the dung source,

通常把它埋在離糞源教遠的地方，

and they have a very particular behavior

且他們滾球的方式

by which they are able to roll their balls.

是非常特定的。

So this is a very proud owner of a beautiful dung ball.

這是非常驕傲地美麗糞球擁有者。

You can see it's a male

你可以看到牠是公的，

because he's got a little hair on the back of his legs there,

因為牠的腿後面有毛髮，

and he's clearly very pleased about what he's sitting on there.

且牠對於自己正坐著的東西顯然非常高興。

And then he's about to become a victim

然後牠就要成為

of a vicious smash-and-grab. (Laughter)

惡毒的破窗行竊行為的受害者。（笑聲）

And this is a clear indication

這很明確地表示

that this is a valuable resource.

這是一個寶貴的資源。

And so valuable resources have to be looked after

因此，寶貴的資源必須得到照顧和

and guarded in a particular way, and we think

特定的看守，我們認為

the reason they roll the balls away is because of this,

這是牠們將糞球滾走的的原因，

because of the competition that is involved

因為擁有糞便

in getting hold of that dung.

涉及競爭。

So this dung pat was actually -- well, it was a dung pat

所以這糞墊是--嗯，至少在

15 minutes before this photograph was taken,

這張照片拍攝前15 分鐘是糞墊，

and we think it's the intense competition

我們認為這激烈的競爭

that makes the beetles so well-adapted

是使糞甲蟲非常會

to rolling balls of dung.

滾糞球的原因。

So what you've got to imagine here is this animal here

所以你想像的是這動物

moving across the African veld.

在非洲草原上移動。

Its head is down. It's walking backwards.

牠的頭是向下，牠正向後走。

It's the most bizarre way to actually transport your food in any particular direction,

這是往特定方向運輸食物最離奇的方式，

and at the same time it's got to deal with the heat.

並在同一時間還得耐熱。

This is Africa. It's hot.

這是非洲。很熱的。

So what I want to share with you now

所以我現在想要與你們分享

are some of the experiments that myself and my colleagues

一些我和同事們做的實驗

have used to investigate how dung beetles

來研究糞甲蟲如何

deal with these problems.

處理這些問題。

So watch this beetle,

所以看這只糞甲蟲，

and there's two things that I would like you to be aware of.

我想要你們注意兩件事。

The first is how it deals with this obstacle

第一是如何處理我們放在牠的路徑中的障礙物。

that we've put in its way. See, look, it does a little dance,

看看，牠跳一段小舞蹈，

and then it carries on in exactly the same direction

然後它往牠一開始完全相同的

that it took in the first place.

方向前進。

A little dance, and then heads off in a particular direction.

一小段舞，然後往特定的方向前進。

So clearly this animal knows where it's going

很顯然的，這動物知道牠要去哪裡

and it knows where it wants to go,

且知道牠想去哪裡，

and that's a very, very important thing,

且這是非常、 非常重要的，

because if you think about it, you're at the dung pile,

因為如果你想想看，你在糞堆中，

you've got this great big pie that you want to get away from everybody else,

你有一塊你想要搬離其它人的大餅，

and the quickest way to do it is in a straight line.

且最快捷的方法就是直線前進。

So we gave them some more tasks to deal with,

所以我們給了牠們更多的任務，

and what we did here is we turned the world

在這裡做的就是我們在牠們的腳下

under their feet. And watch its response.

旋轉世界。觀察牠的反應。

So this animal has actually had the whole world

所以實際上整個世界被旋轉了，

turned under its feet. It's turned by 90 degrees.

旋轉了 90 度。

But it doesn't flinch. It knows exactly where it wants to go,

但牠不會退縮。牠很確切地知道牠想要去哪，

and it heads off in that particular direction.

且牠仍朝著那個方向前進。

So our next question then was,

所以我們接下來的問題是

how are they doing this?

牠們如何做到的？

What are they doing? And there was a cue that was available to us.

牠們在做什麼？我們有個線索。

It was that every now and then they'd climb on top of the ball

就是牠們有時候會爬到球上

and they'd take a look at the world around them.

看看周圍的世界。

And what do you think they could be looking at

你認為牠們爬上球時

as they climb on top of the ball?

在看什麼？

What are the obvious cues that this animal could use

這種動物最有可能找什麼樣的線索

to direct its movement? And the most obvious one

來幫助牠的直線運動？最直接的

is to look at the sky, and so we thought,

是看看天空，於是我們就想，

now what could they be looking at in the sky?

牠們可能在天空中的什麼？

And the obvious thing to look at is the sun.

最直接的是看太陽。

So a classic experiment here,

所以一個經典的實驗

in that what we did was we moved the sun.

就是改變太陽的位置。

What we're going to do now is shade the sun with a board

我們罩住太陽

and then move the sun with a mirror

然後利用鏡子

to a completely different position.

將太陽移到完全不同的位置。

And look at what the beetle does.

然後觀察糞甲蟲。

It does a little double dance,

它跳一小段舞，

and then it heads back in exactly the same direction

然後牠回到跟一開始

it went in the first place.

完全相同的方向。

What happens now? So clearly they're looking at the sun.

發生了什麼？很顯然牠們正在看太陽。

The sun is a very important cue in the sky for them.

太陽對牠們來說是天空中是非常重要的線索。

The thing is the sun is not always available to you,

但問題是太陽並不永遠可以用，

because at sunset it disappears below the horizon.

因為日落後它會消失在地平線下。

What is happening in the sky here

在這裡天空中

is that there's a great big pattern of polarized light in the sky

有大型偏振光圖樣

that you and I can't see. It's the way our eyes are built.

但這是你、我看不見的。我們的眼睛就是這樣。

But the sun is at the horizon over here

但是在這裡，太陽在地平線，

and we know that when the sun is at the horizon,

而我們知道，當太陽在地平線時，

say it's over on this side,

假設它在這一側，

there is a north-south, a huge pathway across the sky

穿過天空南北有一道巨大的、

of polarized light that we can't see

我們看不見的偏振光

that the beetles can see.

但甲蟲是看得到的。

So how do we test that? Well, that's easy.

所以我們要怎麼測試呢？這很容易。

What we do is we get a great big polarization filter,

我們用一巨大的偏振濾光片，

pop the beetle underneath it, and the filter is at right angles

將甲蟲放在下面，濾片與天空的偏振

to the polarization pattern of the sky.

呈直角。

The beetle comes out from underneath the filter

甲蟲從篩選器下出來

and it does a right-hand turn,

然後向右轉彎，

because it comes back under the sky

因為牠回到原本的天空下，

that it was originally orientated to

回到最初的定位，

and then reorientates itself back

又重新

to the direction it was originally going in.

回到本來的方向。

So obviously beetles can see polarized light.

所以很明顯地甲蟲可以看到偏振光。

Okay, so what we've got so far is,

好，所以目前為止我們知道

what are beetles doing? They're rolling balls.

甲蟲的什麼？牠們會滾球。

How are they doing it? Well, they're rolling them in a straight line.

牠們如何滾？滾在一條直線上。

How are they maintaining it in a particular straight line?

牠們如何保持在特定的直線？

Well, they're looking at celestial cues in the sky,

牠們在看天空中的天體線索，

some of which you and I can't see.

其中一些是我們看不見的。

But how do they pick up those celestial cues?

但牠們如何偵測這些天體線索？

That was what was of interest to us next.

那正是我們的下一步。

And it was this particular little behavior, the dance,

這種跳舞的行為

that we thought was important, because look,

讓我們覺得是重要的，

it takes a pause every now and then,

因為看牠時不時暫停一下，

and then heads off in the direction that it wants to go in.

然後爬往牠想要去的方向。

So what are they doing when they do this dance?

所以牠們在跳這種舞蹈時到底在做什麼呢？

How far can we push them before they will reorientate themselves?

所以在牠們重新定位前我們可以改變多少呢？

And in this experiment here, what we did was we forced them

在這個實驗中，我們強迫牠們

into a channel, and you can see he wasn't

進入一個通道，你可以看到牠並不是

particularly forced into this particular channel,

特別被強迫到此特定的通道，

and we gradually displaced the beetle by 180 degrees

我們逐漸將甲蟲轉 180 度

until this individual ends up going in exactly the opposite direction

直到牠跟原來的方向

that it wanted to go in, in the first place.

完全相反。

And let's see what his reaction is

讓我們看看牠的反應是什麼。

as he's headed through 90 degrees here,

在這裡轉 90 度了，

and now he's going to -- when he ends up down here,

現在，牠要 — 當牠到尾端時

he's going to be 180 degrees in the wrong direction.

牠將會轉了 180 度。

And see what his response is.

看看牠的反應是什麼。

He does a little dance, he turns around,

牠跳一小段舞，轉過身，

and heads back in this. He knows exactly where he's going.

再回到這裡面。牠完全知道牠要去哪。

He knows exactly what the problem is,

牠知道問題是什麼，

and he knows exactly how to deal with it,

並知道如何處理，

and the dance is this transition behavior

且舞蹈是這中間的過渡行為

that allows them to reorientate themselves.

讓牠們能夠重新調整。

So that's the dance, but after spending many years

就是這個舞蹈。但經過多年

sitting in the African bush watching dung beetles on nice hot days,

坐在很熱的非洲叢林中看甲蟲，

we noticed that there was another behavior

我們注意到有另一個

associated with the dance behavior.

與舞蹈行為相關聯的行為。

Every now and then, when they climb on top of the ball,

時不時，牠們會爬到球上

they wipe their face.

擦拭自己的臉。

And you see him do it again.

你看到牠又做了一次。

Now we thought, now what could be going on here?

所以我們在想這裡是發生什麼事呢？

Clearly the ground is very hot, and when the ground is hot,

很顯然地是很熱的，且當地面很熱時，

they dance more often, and when they do this particular dance,

牠們更常跳舞的時候，且當牠們跳舞時，

they wipe the bottom of their face.

牠們會擦自己臉的底部。

And we thought that it could be a thermoregulatory behavior.

我們認為這可能是一種體溫調節的行為。

We thought that maybe what they're doing is trying to

我們猜測牠們正在試著

get off the hot soil and also spitting onto their face

離開發燙的土壤並往臉上吐液體

to cool their head down.

來將頭部降溫。

So what we did was design a couple of arenas.

所以我們設計了一些環境。

one was hot, one was cold.

一熱一冷。

We shaded this one. We left that one hot.

我們將這個放在陰影下，另外那個就在熱環境下。

And then what we did was we filmed them with a thermal camera.

然後我們用熱相機拍攝牠們。

So what you're looking at here is a heat image

你們現在正在看的這是熱圖像，

of the system, and what you can see here emerging

你們可以看到從糞便出來的

from the poo is a cool dung ball.

是一個冷的糞球。

So the truth is, if you look at the temperature over here,

因此，事實是，如果從溫度角度看，

dung is cool. (Laughter)

糞便是很冷的。（笑聲）

So all we're interested in here is comparing the temperature

所以我們有興趣的是比較

of the beetle against the background.

甲蟲和環境的溫度。

So the background here is around about 50 degrees centigrade.

這裡環境溫度約攝氏 50 度。

The beetle itself and the ball are probably around about

甲蟲本身和糞球

30 to 35 degrees centigrade,

大約是攝氏30 到 35 度，

so this is a great big ball of ice cream

所以這是一大球冰淇淋

that this beetle is now transporting across the hot veld.

正被甲蟲在熱草原中運送。

It isn't climbing. It isn't dancing, because

牠並不攀爬也不跳舞，

its body temperature is actually relatively low.

因為牠身體的溫度是相對較低的，

It's about the same as yours and mine.

大約和你我的體溫差不多。

And what's of interest here is that little brain is quite cool.

在這裡很有趣的是這小小的頭腦是很涼的。

But if we contrast now what happens in a hot environment,

但如果我們跟熱環境溫度比較，

look at the temperature of the soil.

看看土壤的溫度，

It's up around 55 to 60 degrees centigrade.

大約是攝氏 55 至 60 度左右。

Watch how often the beetle dances.

觀察甲蟲跳舞的頻率，

And look at its front legs. They're roaringly hot.

看看牠的前腿。牠們非常熱。

So the ball leaves a little thermal shadow,

所以球有一些擋熱的效果，

and the beetle climbs on top of the ball

且甲蟲爬上球和擦臉的行為，

and wipes its face, and all the time it's trying to cool itself down,

都是在試圖冷卻體溫。

we think, and avoid the hot sand that it's walking across.

我們認為，這樣亦可避掉它走過的熱沙子。

And what we did then was put little boots on these legs,

我們在它們的腿上穿上小靴子，

because this was a way to test if the legs

因為這是一個測試腿

were involved in sensing the temperature of the soil.

是否能感受土壤的溫度。

And if you look over here, with boots they climb onto the ball

你們看，穿上靴子後

far less often when they had no boots on.

牠們比較不常爬上球。

So we described these as cool boots.

所以我們將這稱為冷靴子。

It was a dental compound that we used to make these boots.

我們用牙醫材料來製作這些靴子。

And we also cooled down the dung ball, so we were able

我們也將糞球冷卻，

to put the ball in the fridge, gave them a nice cool dung ball,

我們把球放到冰箱裡，給牠們一個很冷的糞球，

and they climbed onto that ball far less often

發現牠們爬到球上的次數

than when they had a hot ball.

遠小於熱球的時候。

So this is called stilting. It's a thermal behavior

所以這叫做跳樁行為。牠是一種熱調試行為

that you and I do if we cross the beach,

就像你我在海灘上

we jump onto a towel, somebody has this towel --

跳到毛巾上，有人有這毛巾-

"Sorry, I've jumped onto your towel." --

「對不起，我跳到您的毛巾。」—

and then you scuttle across onto somebody else's towel,

然後再跳到別人的毛巾，

and that way you don't burn your feet.

這樣你不會燙傷你的雙腳。

And that's exactly what the beetles are doing here.

這正是甲蟲在做的。

However, there's one more story I'd like to share with you,

我有另一個想跟你們分享的故事。

and that's this particular species.

是這種特別的種類。

It's from a genus called Pachysoma.

牠屬於Pachysoma屬。

There are 13 species in the genus, and they have

這個屬當中有 13 個物種，

a particular behavior that I think you will find interesting.

且牠們有我認為你們會覺得很有趣的行為。

This is a dung beetle. Watch what he's doing.

這是糞甲蟲。看牠在做什麼。

Can you spot the difference?

你可以找到不同嗎？

They don't normally go this slowly. It's in slow motion.

牠們通常不是這麼緩慢。這是慢動作。

but it's walking forwards,

牠正在往前走，

and it's actually taking a pellet of dry dung with it.

且帶著一塊糞便。

This is a different species in the same genus

這是同一屬的另一個物種，

but exactly the same foraging behavior.

有著完全相同的的覓食行為。

There's one more interesting aspect of this

另一個關於這糞甲蟲的行為

dung beetle's behavior that we found quite fascinating,

讓我們覺得很有趣的是

and that's that it forages and provisions a nest.

牠覓食和築巢有特定的規則。

So watch this individual here, and what he's trying to do

所以看這隻，

is set up a nest.

牠正在試著築巢。

And he doesn't like this first position,

牠不喜歡這第一個位置，

but he comes up with a second position,

但牠來到第二個位置，

and about 50 minutes later, that nest is finished,

約 50 分鐘後，巢築完了。

and he heads off to forage and provision

然後牠到一堆

at a pile of dry dung pellets.

糞便上覓食。

And what I want you to notice is the outward path

我想要你們注意的是比較

compared to the homeward path, and compare the two.

外出和回家這兩條路徑。

And by and large, you'll see that the homeward path

總的來說，你會看到，回家的路徑

is far more direct than the outward path.

是遠比外出的路徑直接。

On the outward path, he's always on the lookout

在外出的路徑上，

for a new blob of dung.

牠總是在找新的食物來源。

On the way home, he knows where home is,

在回家的路上，牠知道家在哪裡，

and he wants to go straight to it.

且牠想要直接回去。

The important thing here is that this is not a one-way trip,

重要的是這不是一次單程旅行，

as in most dung beetles. The trip here is repeated

大多數甲蟲，這趟食物來源

back and forth between a provisioning site and a nest site.

與家裡的旅程是一直被重複的。

And watch, you're going to see

看，你會看到另一個

another South African crime taking place right now. (Laughter)

南非犯罪發生。（笑聲）

And his neighbor steals one of his dung pellets.

牠的鄰居偷了牠的一個糞便丸。

So what we're looking at here

所以我們這在理看到的

is a behavior called path integration.

是一種叫做路徑積分的行為。

And what's taking place is that the beetle

甲蟲有一個家，

has got a home spot, it goes out on a convoluted path

牠用錯綜複雜的路去尋找食物，

looking for food, and then when it finds food,

然後當牠找到食物，

it heads straight home. It knows exactly where its home is.

牠直接回家。牠明確知道家在哪裡。

Now there's two ways it could be doing that,

有兩種方式可以辦到這個，

and we can test that by displacing the beetle

我們可以將甲蟲

to a new position when it's at the foraging site.

移到新的位置來研究。

If it's using landmarks, it will find its home.

如果牠使用的地標，牠會回得到家。

If it is using something called path integration,

如果牠使用所謂的路徑積分，

it will not find its home. It will arrive at the wrong spot,

它不會找到牠的家。牠會回道錯誤的地方，

and what it's doing here if it's using path integration

如果牠使用路徑積分

is it's counting its steps or measuring the distance out in this direction.

牠會計算在每個方向走過的距離。

It knows the bearing home, and it knows it should be in that direction.

牠知道多遠也知道方向。

If you displace it, it ends up in the wrong place.

如果你移動牠，牠會回到錯誤的地方。

So let's see what happens when we put this beetle

那麼讓我們看看當我們這麼做時

to the test with a similar experiment.

會發生什麼事。

So here's our cunning experimenter.

所以這裡是我們狡猾的實驗者。

He displaces the beetle,

牠移動甲蟲，

and now we have to see what is going to take place.

現在我們要看看到底發生什麼事。

What we've got is a burrow. That's where the forage was.

我們有個巢的位置。那是食物所在。

The forage has been displaced to a new position.

食物被放到新的位置。

If he's using landmark orientation,

如果牠使用地標，

he should be able to find the burrow,

牠應該能夠找回洞穴，

because he'll be able to recognize the landmarks around it.

因為牠能夠辨識牠周圍的地標。

If he's using path integration,

如果牠使用路徑積分，

then it should end up in the wrong spot over here.

那麼牠會回到那邊錯的位置。

So let's watch what happens

讓我們看看當我們在甲蟲上試驗後

when we put the beetle through the whole test.

發生什麼。

So there he is there.

牠在那裡。

He's about to head home, and look what happens.

牠要回家，如何？

Shame.

糟糕。

It hasn't a clue.

牠完全沒有線索。

It starts to search for its house in the right distance

牠開始在適當的距離找牠的房子

away from the food, but it is clearly completely lost.

但牠完全迷失了。

So we know now that this animal uses path integration

所以我們知道，這種動物使用路徑積分

to find its way around, and the callous experimenter

來找到它的路而我們冷酷無情的實驗者

leads it top left and leaves it. (Laughter)

將它領到左上角離開。（笑聲）

So what we're looking at here are a group of animals

所以我們看到的是一群使用羅盤的小動物，

that use a compass, and they use the sun as a compass

牠們利用太陽作為一個指南針

to find their way around,

來找路

and they have some sort of system

且牠們有某種

for measuring that distance,

可以測量距離的系統，

and we know that these species here actually

我們知道，這些物種在實際上

count the steps. That's what they use as an odometer,

計算步伐，那是牠們用來作為里程表的系統，

a step-counting system, to find their way back home.

來找到牠們回家的路。

We don't know yet what dung beetles use.

我們還不知道糞甲蟲是使用什麼。

So what have we learned from these animals

所以我們從這些腦袋只有一粒米大小的

with a brain that's the size of a grain of rice?

動物身上學到什麼？

Well, we know that they can roll balls in a straight line

嗯，我們知道牠們可以在一條直線滾球

using celestial cues.

使用天體的線索。

We know that the dance behavior is an orientation behavior

我們知道舞蹈行為是取向行為，

and it's also a thermoregulation behavior,

也是一種體溫調節的行為，

and we also know that they use a path integration system

我們還知道牠們使用路徑積分系統

for finding their way home.

尋找回家的路。

So for a small animal dealing with a fairly revolting substance

所以以這樣小的動物要處理這麼令人厭惡的東西，

we can actually learn an awful lot from these things

我們事實上可以從中學習很多，

doing behaviors that you and I couldn't possibly do.

看到牠做很多你我做不到的行為。

Thank you. (Applause)

謝謝。（掌聲）