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What exactly is Evolution?

究竟什麼是演化？

In biology, the theory of evolution doesn't tell us exactly how life began on earth but it helps us understand how life, once it came into existence, diversified into the many incredible forms we see now and in the fossil record.

在生物學上，演化論並沒有告訴我們地球上的生命源自何處。但它幫助我們理解生命自存在以來，是如何演變成我們今日看到以及化石顯示的各種形貌。

It also helps us make sense of the way in which modern creatures continue to adapt and changed today.

它也幫助我們理解，為何今日的一些生物持續在適應、演變。

In biology, evolution can be defined as any change in the heritable traits (those are physical traits like fur color in mice, spots on the wings of butterflies or instinctive behaviors like the way that dogs greet their friends with a sniff,) within a population across generations.

在生物學上，演化可被定義為：世代間任何可遺傳特徵的變化 (包含外形特徵如老鼠毛色、蝴蝶翅膀花紋，或是本能行為，如狗互聞氣味打招呼)。

This definition can be a bit confusing, so let's see how it works.

這個定義或許有些難懂。我們來看是它如何運作的。

All healthy living things from single cell amoebas to flowers to dolphins are capable of reproduction.

所有健康的生物，從單細胞阿米巴原蟲、花朵到海豚，都有繁殖的能力。

We have children, we make copies of ourselves.

我們生育後代。我們創造出自己的翻版。

We do this by duplicating our DNA and passing that DNA on to future generations.

我們複製自己的 DNA，然後將它們傳給後代。

DNA is a chain-like chemical stored inside each one of your cells, which tells them how to grow and function.

DNA 是儲存於你細胞內一鏈鏈的化學物質，它們告訴細胞如何生長、運作。

Your DNA contains coded information on how to build you.

你的 DNA 載有建構你的編碼訊息。

The information in your DNA is different than that of , say, a daffodil's DNA, which is why you look and function differently than a daffodil.

你的 DNA 承載的訊息不同於，比如說，水仙花的 DNA，這也是為什麼你的外觀和生理機制都和水仙花不同。

The information in your DNA is slightly different than that of Elvis Presley, which is one of many reasons you don't look or act quite like he did.

你的 DNA 訊息也和貓王的有些不一樣，這是你和他長得不像、舉止也不同的眾多原因之一。

Single celled amoebas and other simple creatures reproduce by copying their DNA inside their guts, moving both copies to either side of their body, splitting in two right down the middle and then growing back to full size.

單細胞生物阿米巴變形蟲和其他構造簡單的生物，藉由在內臟裡複製 DNA、將兩組 DNA 分到身體兩側、將身體由中間一分為二、再長回完整大小來繁殖。

If all goes well the two new amoebas will be exact copies of each other, but in nature things aren't always perfect.

如果一切順利，兩隻阿米巴變形蟲將會長得一模一樣。但在大自然，事情並非一切完美。

When DNA is being copied, errors can occur, which modify the DNA code.

當 DNA 被複製，錯誤有可能發生，因此修改了 DNA 的編碼。

This is what we call a DNA mutation.

我們稱之為「DNA 變異」。

These mutations, which happen completely on accident and randomly to any part of a DNA strand, can produce variation in the body shape and function of the creature who inherits the modified DNA.

這些變異純屬意外且有可能發生在任一段 DNA，繼承了這些變異 DNA 的生物將可能在身形外觀或是生理機制上有改變。

In this case, our new little friend has an arm that stretches extra long.

在這個例子中，我們的新朋友有一隻特別長的手。

If he survives long enough to grow and reproduce, that extra stretchy arm (which is now coded for in his DNA) will be passed on to his children.

如果他活得夠久、得以成長繁衍，那隻特長的手臂 (現在已經被編寫在他的 DNA 裡了) 就會遺傳給後代。

Evolution, any change in the heritable traits within a population across generations, has officially occurred.

「演化：任何世代間可遺傳特徵的改變」正式發生了。

Reproduction for dolphins and badgers and people is a little more complicated.

海豚、獾和人類的繁殖過程稍微複雜。

We have to find ourselves a partner.

我們必須先給自己找伴侶。

When two a badgers get together and you know... fall in love, a sperm cell from the father which contains a copy of half of his DNA, only half, combines with the egg cell of the mother, which contains half a copy of her DNA.

當兩隻獾在一起然後你瞭的 …… 墜入愛河，載有爸爸一半基因的精子細胞會和載有媽媽一半基因的卵子細胞結合。

The result is a brand new cell with a complete set of DNA instructions – all the information needed to divide and grow up into a brand new badger.

結果是一個全新的細胞，擁有一組完整的 DNA 序號。所有要用於細胞分裂及細胞生長成一隻全新小獾的訊息。

The new child matures to be similar to her parents but also unique, because she developed some traits from a mother's DNA and some from her father.

這個新成員會長得越來越像她的爸媽，卻也是獨特的個體，因為她同時繼承了來自媽媽和爸爸的一些特徵。

Her new combination of traits can be passed on to her children and again.

新組合的特徵將能夠由她再遺傳給她的孩子。

Evolution, any change in the heritable traits within a population across generations, has officially occurred.

「演化：任何世代間可遺傳特徵的改變」正式發生了。

Besides the unique recombination of her parents' traits, she might also have developed some completely new traits of her own due to DNA mutations.

除了遺傳自爸媽的、那套重新組合的特徵，因著 DNA 變異，她或許也會發展出自己獨有的新特徵。

Maybe, extra hairy ears for example.

舉例來說，一對特別毛茸茸的耳朵。

If she survives long enough to have kids, her DNA will combine with the DNA of her partner and she'll pass on those extra hairy ears to at least some of her children.

如果她存活到繁衍後代，她的 DNA 將會和伴侶的 DNA 結合。然後她就會將那對毛茸茸耳朵傳給其中幾個後代。

Again, evolution has officially occurred.

「演化」再一次正式發生了。

So there you have it.

所以就是如此這般。

Evolution is really pretty simple.

演化其實並不複雜。

Scientists and normal folks everywhere witness evolution happening all the time.

科學家及世界各地你我一般的普通人天天都在見證「演化」。

Small changes like the ones we've seen here can add up over multiple generations to create dramatic changes.

我們在這個例子中看到的小改變，有可能在累積了幾個世代後造成巨大變化。

If you were to go back in time just a few thousand years, you'd find that all dogs, for example, originally evolved from an ancestral group of gray wolves.

舉個例子，如果你回到幾千年前，你會發現所有的狗其實都源自於一群狼祖先。

The evolution of those wolves from generation to generation was guided by humans.

那些狼的世代演化經由人來操縱。

People were selecting wolves with the traits they liked, letting them breed and then only keeping the puppies with the most desirable traits.

人們選擇那些特徵令人喜愛的狼，讓牠們育種，然後留下特徵最符合需求的幼狼。

As time went on, different breeders preferred dogs with different features, some selected for large size, some for small size, some for brains, others for brawn.

隨著時間過去，不同的育種人偏愛有不同特徵的狼。有些特別挑選身形大的，有些要小身形的，有些要聰明的，有些要健壯的。

Today wolves have branched out into hundreds of breeds – very few of which look and behave much like their ancestors.

在今日，狼演變成幾百種的狗。其中極少外觀或行為像是牠們的祖先。

A massive amount of observable evidence from many different fields such as genetics, chemistry, paleontology, and mathematics, overwhelmingly suggest that just like all dogs share common ancestor, all living things, me, you, puffer fish, banana trees, if you go back far enough, also share a common ancestor.

來自遺傳學、化學、古生物學及數學的大量證據壓倒性地指出：所有的生物，你、我、河豚、香蕉樹，皆源自同一位古老祖先。

We are literally related.

我們確實和彼此有所關聯。

We don't know what the first life form was or exactly how it came to be but the simple process of reproduction with variation over billions of years looks to be responsible for all the diversity of life we see today.

我們無從得知最早的生物形態為何，或牠究竟來自哪裡。不過「繁殖變異」這個簡單的過程，該是幾十億年來生物多樣性的起因。

Now you might be saying, "Wait a minute, hold on here, isn't evolution random?"

現在你或許在想，「嘿等等，『演化』不是隨機的嗎？」

To do something functional like turn a wolf into an adorable mini poodle, random evolution had to be carefully guided by an intelligent dog breeder.

為了達到某目的，比如把一隻狼變成可愛的小貴賓狗，「隨機演化」就必須由聰明的犬育種員操縱。

Researchers claim that all mammals evolved from an ancient shrew-like creature.

研究者表示，所有哺乳類動物皆演變自一隻古老的類鼩鼱生物。

But the difference between a shrew and an elephant is far greater than that of a wolf and a poodle.

但是鼩鼱和大象的差別性可是遠遠大於狼和貴賓狗。

Who guided that process?

這過程誰操縱的？

Who was the breeder?

「育種人」是誰？

In the mid-eighteen-hundreds two men, Charles Darwin and Alfred Russel Wallace, independently discovered that a breeder is not necessarily needed.

在十八世紀中葉，兩名男子 —— 查爾斯．達爾文和阿爾弗雷德．羅素．華萊士，發現「育種人」其實可有可無。

There is another force capable of guiding random evolution to produce order and complex function.

有另一個機制足以操縱「隨機演化」，製造出規律和複雜的機能。

They called it "natural selection," which happens to be the entire topic of our next video.

他們稱之為「自然選擇」，這也是我們下一部影片的主題。

But before you move on, let's recap what we've learned so far.

但在你進入下一章前，我們先來複習目前說過的。

Biological evolution is any change in the heritable traits within a population across generations.

「生物演化」就是任何世代間可遺傳特徵的改變。

All healthy living things can make copies of themselves, but they do so imperfectly.

所有健康的生物都能夠繁衍後代，但過程不見得完善。

Small variations can add up over generations to create dramatic differences in the body form and function of living creatures.

小小的變異有可能累積幾個世代以後造成生物外觀及機能的劇烈演變。

Evidence overwhelmingly suggests that all life on earth is related.

證據壓倒性地指出，地球上的所有生物都是有關聯的。

So remember next time you invite family and friends over for a holiday feast, you're actually just inviting family that includes the turkey and the pumpkin in the pumpkin pie.

所以記得，下一次節日你邀請別人家或是朋友聚餐，你等於邀請了一個包含火雞、南瓜派裡的南瓜的家庭。

I'm Jon Perry and that's evolution (by) Stated Clearly.

我是 Jon Perry，以上是 Stated Clearly 的「演化课程」。

Thanks for watching our show. I hope you enjoyed it.

感謝收看我們的節目。希望你喜歡。

Make sure to give us a thumbs up on YouTube and subscribe to us if you want to see more.

別忘了在 YouTube 給我們按個讚然後訂閱，將來才能看到更多影片哦。

Stated Clearly is funded by our viewers and we are in need of support.

Stated Clearly 由觀眾贊助，我們需要大家的協助。

If you like what we do, consider contributing.

如果你喜歡我們的節目，請考慮贊助。

You can do so by visiting our website at StatedClearly.com.

你可以到我們的網站 StatedClearly.com 提供贊助。

This episode was made possible by viewer contributions and by generous donations from Bird and Moon Comics and ProofAvenue.

本節目要感謝以下的慷慨贊助：鳥月漫畫、ProofAvenue 及各位觀眾。

Make sure to check out Bird and Moon's awesome biology comic strips and posters at birdandmoon.com and check out the musical talent of AD at proofavenue.com.

記得去看看鳥月漫畫的生物漫畫，以及 birdandmoon.com 上的海報。以及 proofavenue.com 上的 AD 音樂。

Until next time.

下回見啦。

Stay curious!

隨時保持好奇心！