Why animals help each other - Ashley Ward

譯者: Lilian Chiu 審譯者: 麗玲 辛

These humpback whales have already covered thousands of kilometers

這些座頭鯨已經游了數千公里，

on their migration from tropical breeding grounds to colder feeding grounds.

牠們要從熱帶的繁殖地 遷徙到較冷的覓食地。

But one of these whales is about to take a detour.

但其中一隻鯨魚要先繞去一個地方。

From several kilometers away, it hears a group of orcas harassing a seal,

牠聽到幾公里外有一群虎鯨 在騷擾一隻海豹，

and— as if answering a distress signal— it races off.

就像在回應求救訊號一樣， 牠迅速前往現場。

The humpback charges the 8-meter-long orcas,

這隻座頭鯨衝向八公尺長的虎鯨，

driving them away with its massive pectoral flukes.

用牠巨大的胸鰭把牠們趕走。

Then, when the threat is gone, it swiftly returns to its journey.

威脅解除之後，牠便馬上 返回繼續自己的旅程。

Humpbacks are known to mount these kinds of impromptu rescue missions.

座頭鯨的一個知名特色 就是會展開這種救援任務。

But why would they expend time and energy risking their lives for a stray seal?

但牠們為什麼要花費時間和精力， 冒著生命危險去拯救迷途的海豹？

Isn’t nature a cruel and vicious place, without room for generosity?

大自然不是個殘酷兇惡的地方， 不容許任何慷慨之舉嗎？

Well, sort of.

嗯，算是吧。

The publication of Charles Darwin’s “On the Origin of Species”

查爾斯‧達爾文的書《物種起源》

introduced the notion of survival of the fittest,

提出了適者生存的概念，

creating a lasting vision of Earth’s strongest animals dominating

刻畫出一個讓人難忘的畫面： 地球上最強的動物主宰自然界。

the natural world.

But this isn’t what Darwin meant by fitness,

但達爾文說的適者並不是這個意思，

nor is it how modern biologists define it.

現代生物學家給的定義也不是這樣。

Rather than describing an animal’s physical strength,

適者的「適」並不是指 動物的身體力量，

fitness refers to how likely an organism is to pass on its genes

而是生物將其基因傳給 下一代的可能性有多高。

to the next generation.

This means the fittest animals are those who can survive long enough

也就是說，活得夠久、可以產下 健康後代的動物即是適者。

to produce healthy offspring.

And while that might occasionally describe a powerful predator,

雖然適者可能是 身強體壯的捕食性動物，

the fittest animal can also be the most stealthy, resourceful,

但也有可能是來無影去無蹤、

最足智多謀，或甚至最團結的動物。

or even the most cooperative.

So what exactly does cooperation look like in the animal kingdom?

那麼，動物王國中的 團結合作是什麼樣子的？

Sometimes it's fairly straightforward.

有時候很直接。

In the sun-dappled waters of the Great Barrier Reef,

在大堡礁陽光斑駁的水域中，

cleaner wrasse diligently inspect other fish for parasites,

清潔魚（裂脣魚）會勤奮地 檢查其他魚類是否有寄生蟲，

eating up any blood suckers with a precise nibble.

精確地啄食，吃掉這些吸血寄生蟲。

This kind of arrangement, in which both sides benefit, is known as mutualism.

這種雙方都受益的方式， 就叫做互利共生。

But this particular relationship can also be parasitic.

但互利共生也有可能是寄生的模式。

If a wrasse thinks it can get away with it,

若裂脣魚認為自己能全身而退，

it will try to take a bite of the fish it’s cleaning.

就會嘗試咬一口牠在清潔的魚。

This parasitic turn is only temporary, of course,

當然，轉為寄生模式只是暫時性的，

and the wrasse will quickly return to its usual gourmet grooming.

裂脣魚很快就會繼續做 牠平時的美食梳理工作。

Meanwhile, in the Kalahari Desert, meerkat mobs dig for buried prey.

在卡拉哈里沙漠中，成群的狐獴 會挖掘埋在土裡的獵物。

This technique leaves the foragers vulnerable,

這種方式讓覓食者很容易受到攻擊，

but when an eagle swoops down for a snack,

但是當老鷹俯衝下來獵捕時，

the mob’s appointed sentry cries out.

這群狐獴指派的哨兵就會發出警告。

With lightning speed, the meerkats retreat to the safety of their burrows,

狐獴會以閃電般的速度 躲回牠們安全的洞穴中，

leaving the bird in their dust.

讓老鷹撲個空。

While this arrangement is essential for the foragers,

雖然這種安排對於覓食者至關重要，

the sentries can't eat while on duty,

但哨兵在值班時就不能吃東西，

and sounding a warning puts them directly in the eagles’ line of fire.

且發出警告後，牠們就會 直接成為老鷹的目標。

But despite this roll’s dangers, it might actually increase their fitness.

不過，儘管這份工作很危險， 卻讓牠們更適於生存。

Many evolutionary biologists believe animals improve their odds

許多演化生物學家認為， 動物會用以下兩種方式之一

of passing their genes to the next generation in one of two ways.

提高將其基因傳給下一代的機會：

Either directly by having their own offspring,

直接的方式是生育自己的後代，

or indirectly by helping genetic relatives have offspring.

間接的方式是協助 有共同基因的親屬繁殖後代。

Meerkat sentries may gain this indirect fitness benefit

狐獴可能就是採用間接的方式 來取得適者優勢，

since groups tend to be comprised of closely related individuals.

因為牠們的群體通常是近親組成的。

Of course, animals don't have to be family to protect each other.

當然，動物不見得只會保護家屬。

For Costa Rican vampire bats, just a few unsuccessful hunts can mean starvation.

對哥斯大黎加吸血鬼蝙蝠來說，

幾次狩獵失敗可能就得餓肚子。

So it's fortunate that when a bat is dying of hunger,

很幸運的是，當一隻蝙蝠快餓死時，

another bat might regurgitate some of its own meal to help its roost mate

另一隻蝙蝠可能會吐出一些食物

以協助牠的同伴度過這段艱難時期。

through this lean period.

This is a considerable cost for the gifting bat.

對於給予食物的蝙蝠而言， 這是很大的代價。

But this practice develops a “you scratch my back

但是這種做法會發展出 一種「你幫我抓背，

and I’ll scratch yours” arrangement,

我就幫你抓背」的互惠約定，

more formally known as reciprocal altruism.

更正式的名稱為相惠利他主義。

This isn’t altruism in its purest sense

從最純粹的意義來看， 這並不是利他主義，

because when the donor gives away its hard-won food,

因為當捐贈者送出 牠辛苦得來的食物時，

it does so expecting to receive similar help in the future.

牠其實抱著未來也會 得到類似協助的期待。

But while it’s true that we usually see animals help one another

雖然我們確實常看到動物彼此幫忙，

in exchange for food, fitness, or favors,

以交換食物、適應性，或賣個人情，

that doesn’t mean the animal kingdom is devoid of truly selfless altruism.

那並不表示動物王國中 就沒有真正無私的利他主義。

Researchers still don't know why humpbacks protect unrelated whales

研究者仍然不知道座頭鯨 為什麼要保護無親無故的鯨魚，

and the occasional seal from powerful predators.

還會偶爾保護海豹， 對抗強壯的捕食性動物。

And while it might seem hard to believe this heroic feat is an act of generosity,

雖然似乎很難相信 這種英雄壯舉只是出於慷慨，

who knows what kinds of kindness we may discover

但誰又知道，當我們繼續研究 地球上無數團結合作的生物時，

as we continue investigating Earth’s countless cooperative creatures.

還會發現什麼樣的善良行為。