Name: 模擬攻擊性的演化！ (Simulating the Evolution of Aggression)
Uploaded: 2025-11-19T02:01:51.000Z
Duration: 13 min 17 s

In this video, we're going to start exploring conflict between creatures to try to build some understanding.

在這支影片裡，我們要開始探討生物之間的衝突，試著建立一些理解。

Here, we're going to use some simulations and some ideas from a field of math called game theory.

在這裡，我們會使用一些模擬，以及來自數學領域「賽局理論」的一些概念。

Okay, so in our simulation, food will appear each day and then blobs will appear and go out to eat the food.

好的，在我們的模擬中，每天都會出現食物，然後會有小點點出現，去吃這些食物。

We'll use the same survival and reproduction rules as in previous videos.

我們會沿用之前影片中的生存和繁殖規則。

Eating one piece of food lets a creature survive to the next day, but

吃下一份食物，生物就能生存到隔天，但是

and eating two pieces of food allows a creature to both survive and reproduce.

吃下兩份食物，生物就能生存並繁殖。

What's different in this simulation though, is that food will come in pairs.

不過，這次模擬不同的地方在於，食物會成對出現。

Each creature randomly picks a pair of food to walk to, so it might get the pair all to itself and get to go home with two food and then reproduce.

每個生物會隨機選一對食物走過去，所以牠可能獨享這一對食物，然後帶著兩份食物回家繁殖。

Or another creature might find the pair at the same time.

又或者，可能有另一隻生物同時發現了這一對食物。

And when this happens, they have to somehow figure out how to split things up.

當這種情況發生時，牠們就必須想辦法分配。

We'll start out by having only one possible strategy for creatures who run into each other.

我們先從生物們相遇時只有一種可能的策略開始。

They'll just share each, taking a piece of food and going home to survive to the next day.

牠們會平分食物，各拿一份回家，這樣就能活到隔天。

And because this strategy is so nice, we'll give it the name dove.

因為這個策略這麼溫和，我們就叫牠「鴿子」。

好了，我們先讓模擬跑一陣子。

Alright, now let's add a new strategy called the hawk strategy.

好了，現在我們加入一個叫做「老鷹」的新策略。

If a hawk meets a dove, the hawk will go for the same piece of food as the dove, eat half of it, and

如果老鷹遇到鴿子，老鷹會跟鴿子搶同一份食物，吃掉一半，然後

then quickly eat the other piece of food, taking it for itself.

接著快速吃掉另一份食物，獨自佔為己有。

This half food does complicate our survival and reproduction rules a little bit.

這半份食物確實讓我們的生存和繁殖規則變得有點複雜。

So in this situation, a dove ends the day with half a food then, so it'll have a 50% chance of surviving to the next day.

所以在這種情況下，鴿子一天結束時只剩下半份食物，牠就只有 50% 的機率活到隔天。

And the hawk ends its day with one and a half food, so it'll survive for sure and also have a 50% chance of reproducing.

而老鷹一天結束時會有一份半的食物，所以牠一定能生存，而且有 50% 的機會繁殖。

So it looks good to be a hawk, but it's also risky.

所以當老鷹看起來不錯，但這也有風險。

If two hawks meet, they'll fight, and fighting is taxing.

如果兩隻老鷹相遇，牠們會打鬥，而打鬥很耗費體力。

At the very least, they use a lot of energy and they might also get injured.

至少，牠們會消耗大量能量，而且牠們也可能受傷。

So when hawks fight, each one gets a piece of food, but

所以當老鷹打鬥時，每隻老鷹會得到一份食物，但是

they spend so much energy fighting that they use up all the benefit of the food right away and effectively go home with zero food, meaning they won't survive.

牠們消耗的能量太多了，馬上就消耗掉食物的好處，實際上是零食物回家，這意味著牠們無法生存。

So now let's try adding a hawk creature to our simulation and see what happens.

所以現在讓我們試著在模擬中加入一隻老鷹生物，看看會發生什麼事。

Now is a good time to pause and predict what you think will happen, Sam.

現在是個暫停並預測你會怎麼想的好時機，Sam。

Alright, it looks like we have a mixture that fluctuates roughly around half and half.

好的，看起來我們有一個混合，大約在半半之間波動。

And there are also fewer creatures Overall, even with the same amount of food, here's an example of how natural selection doesn't necessarily act for the good of the species.

而且生物的總數也變少了，即使有相同數量的食物，這就說明瞭自然選擇不一定會為了物種的利益而行動。

And to cover our bases, let's try starting with all hawks.

為了確保萬無一失，我們來試試全部都用老鷹開始。

Okay, not too surprisingly, they're tearing each other apart.

好的，不出所料，牠們互相殘殺。

And their max population size didn't even reach half of the population size of the doves.

而且牠們的最大種群規模甚至沒有達到鴿子種群規模的一半。

Now, if we add a dove to the mix in the next day, what do you think will happen?

現在，如果我們在接下來的一天中加入一隻鴿子到這個混合體中，你覺得會發生什麼事？

Okay, so it took the doves a little while to gain a foothold here, but

好的，所以鴿子在這裡站穩腳跟花了一點時間，但是

eventually we end up in a similar situation with a fluctuating mixture of hawks and doves.

最後我們又回到了類似的情況，老鷹和鴿子混合體波動不定。

Well, this is a situation where survival of the fittest doesn't help us understand what's going on.

嗯，這是一個「適者生存」無法幫助我們理解正在發生什麼的情況。

We can get a better sense for why this is by translating our conflict rules from before into a table.

我們可以透過將之前的衝突規則轉換成表格，來更好地理解為什麼會這樣。

If two doves face each other, they'll each get one food.

如果兩隻鴿子對上，牠們各自會得到一份食物。

If a dove faces a hawk, the dove gets half a food and the hawk gets one and a half or three halves food.

如果鴿子對上老鷹，鴿子會得到半份食物，老鷹則會得到一份半或三份之二的食物。

And if we reverse perspectives, if a hawk faces a dove, they'll get three halves and one half.

如果我們換個角度，老鷹對上鴿子，牠們會得到三份之二和半份。

And when a hawk faces another hawk, they'll each end up with zero after they waste all that energy fighting each other.

而當老鷹對上另一隻老鷹時，牠們都會因為打鬥耗盡能量而一無所獲。

Now that we have this table, let's imagine blobs that can choose which strategy they want to play.

現在我們有了這個表格，讓我們想像一下可以選擇想玩的策略的群體。

Say I control the blob on top and you control the blob on the left.

假設我控制上面的群體，你控制左邊的群體。

Say you know that I'm going to play a hawk strategy, which of course, I am.

假設你知道我會採取老鷹策略，當然，我會的。

Well, you're better off just backing down and taking your half food.

嗯，你最好還是退縮，拿走你的半份食物。

That might be annoying since it feels like I'm winning somehow.

這可能會讓你有點惱火，因為感覺上我 somehow 贏了。

And you might be tempted to challenge me and also play hawk to teach me that I can't just push you around.

而且你可能會忍不住想挑戰我，也採取老鷹策略，來教訓我不能這樣欺負你。

This could make sense if we were going to play this game against each other over and over again, as true humans might do.

如果我們要一次又一次地玩這個遊戲，就像真正的人類一樣，這樣做是說得通的。

And that is something we'll talk about in future videos.

這點我們會在未來的影片中討論。

But in this situation, we're just these simple blobs with no social structure interacting once.

但在這種情況下，我們只是這些沒有社會結構、只互動一次的簡單色塊。

And even if we do see each other again, we won't remember it.

就算我們再次見面，也不會記得。

So all that matters is how much food we take home right now.

所以現在最重要的是我們能帶走多少食物回家。

And if you want to maximize your chances of surviving and reproducing, you'll play dove.

如果你想最大化你生存和繁殖的機會，你會採取鴿子策略。

Here, let's record this by drawing an arrow if we're in the right hand column, because I'm Playing hawk, the situation in the upper right square is the best you can do.

好的，讓我們在這裡記錄下來，如果你在右邊的欄位，就畫個箭頭，因為我採取老鷹策略，右上角的那個格子就是你能做到的最好的。

Okay, in the other case, where I'm not so mean, you know that I'm going to play the dove strategy.

好的，在另一種情況下，如果我沒那麼壞，你知道我會採取鴿子策略。

In this case, you'll do better playing hawk.

在這種情況下，你採取老鷹策略會比較好。

And here again, because you're a very smart human, you might be tempted to think about the future and want to reward me for playing nice and play dove yourself.

這裡又一樣了，因為你很聰明，你可能會想著未來，想獎勵我扮演好人，然後自己也扮演鴿子。

But we're just these really simple blob creatures who might never see each other again.

但我們只是這些很單純的生物，可能再也不會見面了。

So if you want to maximize your chance of reproducing, you'll play hawk, and

所以如果你想最大化你的繁殖機會，你會採取老鷹策略，然後

我們可以用另一個箭頭來記錄。

So now, to complete this table, we can reverse perspectives and think about what I should do in response to you, which I won't go through in detail.

所以現在，為了完成這個表格，我們可以反過來思考，想想我該如何回應你，這部分我不會詳細說明。

It's the same reasoning, but we'd get similar arrows in the rows here.

理由一樣，但我們會得到類似的箭頭在這些列裡。

These arrows all point to more advantageous strategies.

這些箭頭都指向更有利的策略。

And the interesting thing to notice is that there are two stable situations.

有趣的是，這裡有兩種穩定的情況。

Either you play hawk and I play dove, or you play dove and I play hawk.

要嘛你扮演老鷹我扮演鴿子，要嘛你扮演鴿子我扮演老鷹。

If we're in one of those two situations, either one of us would be worse off if we pick a different strategy.

如果我們處於這兩種情況的其中一種，那麼我們任何一方如果選擇不同的策略都會變得更糟。

And by the way, this way of analyzing choices is called game theory, which is a whole field of math.

順帶一提，這種分析選擇的方式叫做賽局理論，這是一整個數學領域。

And a situation where nobody benefits from changing their strategy is called a Nash equilibrium, named after John Nash, who some would say had a beautiful mind.

而沒有人能從改變策略中獲益的情況，就叫做納許均衡，是以約翰·納許命名的，有些人會說他有著一顆美麗的心。

所以最好的策略不是老鷹也不是鴿子。

It's to do the opposite of what your opponent is doing.

When there are a lot of doves, it's better to be a hawk, and

當有很多鴿子時，扮演老鷹比較好，而

when there are a lot of hawks, it's better to be a dove.

當有很多老鷹時，扮演鴿子比較好。

There's some equilibrium fraction of doves that the population has always pulled toward great.

物種總會被拉向一個穩定的鴿子比例，這個比例會讓整體表現很棒。

So we have the main conceptual point down, but

所以我們已經掌握了主要的觀念，但是

we can deepen our understanding by calculating what that equilibrium fraction should be.

我們可以計算出這個穩定的比例應該是多少，來加深我們的理解。

The population will be in equilibrium if doves and hawks have the same expected average score in a contest.

當鴿子和老鷹在比賽中預期平均分數相同時，種群將處於平衡狀態。

Equilibrium is when, on average, we don't expect to change one way or the other.

平衡就是說，平均來說，我們預期不會有任何一方變得更好或更差。

So we can't have one strategy doing better.

所以我們不能讓某一種策略表現得更好。

Our goal is to find the fraction of doves that makes this condition true.

我們的目標是找出鴿子的比例，讓這個條件成立。

On our way there, let's first calculate the expected average score for a dove in a hypothetical example, say, where the rest of the population is 90% doves.

在此之前，我們先來計算一下，在一個假設的例子中，鴿子的預期平均分數是多少，假設人口中有 90% 是鴿子。

So let's see, a dove will have a 90% chance of facing another dove, in which case it gets the dove versus dove payoff of one food and a dove also has a 10% chance of facing a hawk, Right?

所以我們來看看，一隻鴿子有 90% 的機會遇到另一隻鴿子，這種情況下牠會得到鴿子對鴿子的獎勵，也就是一份食物；鴿子也有 10% 的機會遇到老鷹，對吧？

That's just the rest of the creatures, in which case it only gets a half a food.

這就是剩下那些生物，這種情況下牠只會得到半份食物。

So overall, when a dove runs into another creature, when the rest of the population is 90% doves, it'll come away with 0.95 food on average.

所以總體來說，當一隻鴿子遇到另一個生物時，如果人口中有 90% 是鴿子，牠平均會得到 0.95 份食物。

This number is pretty meaningless on its own.

But once we calculate the expected HOX score, we can compare the two to see whether the equilibrium condition is met.

但一旦我們計算出預期的老鷹分數，我們就可以比較兩者，看看平衡條件是否達成。

It could be good to pause and try to do this yourself to make sure it all makes sense, maybe even rewinding to watch the dove part again.

你可以在這裡暫停，試著自己做一遍，確保一切都說得通，甚至可以倒回去再看一遍鴿子的部分。

Okay, just like before, the rest of the population is 90% doves.

好的，就像之前一樣，人口中有 90% 是鴿子。

And against a dove, a hawk gets one and a half or three halves, pieces of food.

而遇到鴿子時，老鷹會得到一份半，也就是三份之二的食物。

And again, there's a 10% chance of running into another hawk, in which case our hawk goes home with zero food, and

而且，牠有 10% 的機會遇到另一隻老鷹，這種情況下，我們的老鷹就只能帶回零份食物，

字幕列表影片播放

模擬攻擊性的演化！ (Simulating the Evolution of Aggression)

assume

strategy

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