演講MP3+雙語(yǔ)文稿:一個(gè)新的祖先物種是如何改變我們的人類(lèi)進(jìn)化理論的？

聽(tīng)力課堂TED音頻欄目主要包括TED演講的音頻MP3及中英雙語(yǔ)文稿，供各位英語(yǔ)愛(ài)好者學(xué)習(xí)使用。本文主要內(nèi)容為演講MP3+雙語(yǔ)文稿:一個(gè)新的祖先物種是如何改變我們的人類(lèi)進(jìn)化理論的？，希望你會(huì)喜歡！

【演講者及介紹】Juliet Brophy

古人類(lèi)學(xué)家朱麗葉-布羅菲（Juliet Brophy）探討了南部非洲的人類(lèi)進(jìn)化。

【演講主題】一個(gè)新的祖先物種是如何改變我們的人類(lèi)進(jìn)化理論的？

【中英文字幕】

翻譯者Doris Zhang 校對(duì)者Yolanda Zhang

00:13

Human origins. Who are we? Where do we come from, and how do we know? In my field, paleoanthropology, we explore human origins -- the "who" and "where" questions -- by analyzing fossils that date back thousands and even millions of years. In 2015, a team of colleagues and I named a new species in the genus Homo -- our genus -- Homo naledi. Let's take a step back and put that into context.

人類(lèi)是如何起源的？ 我們是誰(shuí)？ 我們從哪里來(lái)？ 又是怎么知道的呢？ 在我們古人類(lèi)研究領(lǐng)域， 我們通過(guò)分析幾千年前， 甚至百萬(wàn)年前的化石， 來(lái)探索人類(lèi)的起源—— 回答“是誰(shuí)”和“在哪里”的問(wèn)題。 2015年，我和一個(gè)考察小組 命名了一個(gè)新發(fā)現(xiàn)的人類(lèi)物種—— 我們的人屬—— 奈勒迪人。 來(lái)回顧一下這個(gè)過(guò)程， 就會(huì)更容易理解。

00:47

The last common ancestors between humans and chimps date somewhere between six and eight million years. The earliest hominins, or earliest human ancestors, evolved into a group known as the australopithecines. The australopithecines evolved into the genus Homo and eventually modern humans -- us.

最晚發(fā)現(xiàn)的猿和人的共同祖先， 可以追溯到600到800萬(wàn)年前。 最早的人類(lèi)， 或者說(shuō)人類(lèi)最遠(yuǎn)的祖先， 進(jìn)化為我們所說(shuō)的南方古猿。 這些南方古猿進(jìn)化為人屬， 并最終進(jìn)化成現(xiàn)代人類(lèi)——我們。

01:09

With each new fossil discovery, we get a little bit closer to better understanding who we are and where we came from. With these new fossil finds, we realize we now have to make changes to this tree. Until this discovery, we thought we had a pretty good idea about the patterns of evolutionary change. Current fossil evidence suggests that the earliest populations of the genus Homo evolved in Africa somewhere between two and three million years. Fast-forward to approximately 300,000 years to where we see the origins of the first modern humans. While the fossil record between these time frames in Africa is relatively sparse, the fossils nonetheless demonstrated certain trends from our earliest ancestors to modern humans. For example, our brains were becoming larger relative the rest of our body. Our pelves were becoming more bowl-shaped, and our hand-wrist morphology, or form, suggested a change in our grip as we began to make and use stone tools and spend less time in the trees. These new fossils disrupt everything we thought we knew about these trends and force us to change the way that we think about human evolution.

隨著每種新化石的發(fā)現(xiàn)， 我們都會(huì)更接近那個(gè)答案， 更能理解我們是誰(shuí)， 我們從哪里來(lái)。 基于這次新的化石發(fā)現(xiàn)， 我們意識(shí)到必須改變這個(gè)樹(shù)形圖。 在這次的發(fā)現(xiàn)之前， 我們以為自己對(duì)進(jìn)化的 模式有個(gè)很好的概念， 現(xiàn)有的化石證據(jù)顯示， 大概200-300萬(wàn)年前， 最早的人屬在非洲進(jìn)化而成。 快進(jìn)一下，從大概30萬(wàn)年前，到第一批 現(xiàn)代人類(lèi)的出現(xiàn)。 雖然在這個(gè)時(shí)間框架中的化石記錄 相對(duì)稀少， 這些化石還是展示出了 從我們最遠(yuǎn)的祖先到 現(xiàn)代人類(lèi)的特定的演變趨勢(shì)。 比方說(shuō)，相對(duì)于身體的其他部位 我們的大腦變得越來(lái)越大。 我們的骨盆更呈現(xiàn)為盆狀， 并且我們的手腕形態(tài)，或者說(shuō)樣子， 這些表明當(dāng)我們開(kāi)始制造和使用石器時(shí)， 用手抓握的方式產(chǎn)生了變化， 同時(shí)也更少地待在樹(shù)上。 這些新發(fā)現(xiàn)的化石打亂了 我們對(duì)這些演變趨勢(shì)的一切認(rèn)知， 并迫使我們改變對(duì)人類(lèi)進(jìn)化的認(rèn)識(shí)。

02:28

South Africa in general, but the Cradle of Humankind in particular, contains numerous sites where hundreds of thousands of fossils have been found. As an undergraduate student, I fell in love with one of them ... Mrs. Ples. The skull of a 2.1-million-year-old early human ancestor. From that point on, I was determined to go to South Africa and study human evolution. I first traveled there in 2003, and I did get to see my beloved Mrs. Ples.

南非這片土地， 是人類(lèi)發(fā)展的搖籃。 那里無(wú)數(shù)的遺址中， 數(shù)以萬(wàn)計(jì)的化石還未曾被發(fā)現(xiàn)。 在讀本科的時(shí)候，我愛(ài)上了其中一個(gè) 普萊斯先生。 這是我們?cè)?10萬(wàn)年前 一個(gè)早期遠(yuǎn)祖的頭骨。 從那時(shí)起， 我決定去南非，研究人類(lèi)進(jìn)化。 2003年，我第一次去那里， 并有機(jī)會(huì)看望了我深?lèi)?ài)的普萊斯先生。

02:55

(Laughter)

（笑聲）

02:56

But words can hardly convey my excitement when I was chosen as an early career scientist by Lee Berger, a world-renowned paleoanthropologist, to be one of the primary analysts of recently excavated unpublished fossils.

語(yǔ)言根本無(wú)法形容我當(dāng)時(shí)的激動(dòng)心情。 當(dāng)時(shí)我被世界著名的古人類(lèi)學(xué)家李·博格 選為青年科技人員， 并在一個(gè)最近發(fā)掘 但尚未公布的化石遺址，擔(dān)任分析組成員。

03:13

This treasure trove of fossils was being recovered from a new site called the Dinaledi Chamber in the Rising Star cave system. Species are often named based on a skull, a lower jaw, or, very rarely, a handful of postcranial, or below-the-neck, elements. The fossils from Dinaledi were another story altogether. An unprecedented approximately 1800 specimens -- so far -- have been excavated from the Rising Star system, representing at least 15 individual skeletons. The research team that I was invited to join was tasked with describing, comparing and analyzing the fossils, with the difficult goal of identifying to what species the fossils belonged. We were divided up into our different areas of expertise. We were divided up in different areas of the lab, too. So there was "Hand Land," for the fossil hand people, "Hip Heaven" for the pelvis ... I was in the "Tooth Booth."

這個(gè)化石寶藏是在一個(gè)叫 Dinaledi Chamber的新遺址里發(fā)現(xiàn)的 屬于瑞星洞系。 我們以往常常根據(jù)頭顱骨，下顎， 或者，極少見(jiàn)的情況下， 一把顱后骨或者頸下骨的特點(diǎn)命名標(biāo)本。 在Dinaledi發(fā)現(xiàn)的化石卻是不同的情況。 在瑞星系列洞穴出土了 大概1800件的標(biāo)本—— 到目前為止—— 這是一個(gè)史無(wú)前例的數(shù)目， 它至少可以拼成15具獨(dú)立的骨架。 我參加的那個(gè)研究小組收到一項(xiàng)任務(wù)， 對(duì)這些難以分辨哪一塊 屬于哪一具骨架的化石 進(jìn)行描述，比較和分析。 我們被分成了不同領(lǐng)域的專項(xiàng)組。 還被分配到了不同領(lǐng)域的實(shí)驗(yàn)室。 因此，這里有"Hand Land," 一個(gè)專門(mén)研究手的小組， "Hip Heaven" 是骨盆專家們... 我是研究牙齒的，在 "Tooth Booth"組。

04:15

(Laughter)

（笑聲）

04:16

And after long, intense days in the lab, the different teams would meet up at night and discuss our findings, still consumed by questions from our analyses. It was incredible how different the interpretations were. Each body part seemed to come from a different species, based on what we knew from the fossil record. The suite of characteristics we were seeing didn't match any known species. And if we had only recovered the skull, we might have called it one thing; if we had only recovered the pelvis, we might have called it another. The anatomy of the skeletons didn't make sense with the framework of what we thought we knew of human evolution. Did it belong in the genus Homo? Should it be an australopithecine? Those bipedal, more apelike ancestors? Or perhaps it should be its own species.

盡管在實(shí)驗(yàn)室里勞碌了一整天， 晚上，不同小組成員 還要開(kāi)會(huì)，討論新的發(fā)現(xiàn)， 我們?nèi)匀荒軐?duì)分析過(guò)程中 產(chǎn)生的問(wèn)題興致勃勃。 你難以相信有多少種不同的解釋。 根據(jù)我們已知的化石記錄， 每一個(gè)身體部位都好像是 來(lái)自一個(gè)不同的物種。 我們眼前的這些化石特點(diǎn)不能和 任何已知物種相匹配。 如果只發(fā)現(xiàn)了這個(gè)顱骨， 我們也許會(huì)稱做它是一種東西； 如果只發(fā)現(xiàn)了這個(gè)骨盆， 我們也許會(huì)稱它為另一個(gè)東西。 當(dāng)我們用自以為正確的 人類(lèi)進(jìn)化論模式思考時(shí)， 對(duì)這些骨骼的刨析就站不住腳。 它屬于人屬嗎？ 它會(huì)是一種南方古猿嗎？ 這些兩足動(dòng)物，更像我們的類(lèi)猿祖先嗎？ 或許它應(yīng)該自成一個(gè)物種。

05:06

Ultimately, after much deliberation, we decided the Rising Star specimens did indeed warrant a new species, which we called "Homo naledi." From the head to the feet, the fossils present a mosaic of primitive, or ancestral, and derived or more modern-like features. The skull is quite derived, appearing most similar to early representatives of the genus Homo, like Homo habilis and Homo erectus. However, the brain is scarcely half the size of a modern human one. One that is smaller than any other early Homo that has ever been found.

最終，在反復(fù)商議之后， 我們決定把這種瑞星標(biāo)本 列為一個(gè)新的物種， 就叫奈勒迪人。 這些化石從頭至腳 呈現(xiàn)出兩種特征的混合： 原始的，或者說(shuō)先祖的特征 和衍生的，更像現(xiàn)代人的特征。 這個(gè)頭骨是衍生的。 它和早期人類(lèi)的特征最相似， 就像巧人和直立人一樣。 然而，它的大腦僅僅是 現(xiàn)代人類(lèi)的一半大小。 它比任何一個(gè)已發(fā)現(xiàn)的 早期人類(lèi)的頭骨都要小。

05:45

As someone who studies teeth, I might argue these are the coolest fossils found at the site.

做為一個(gè)研究牙齒的成員， 我得說(shuō)，這是在這個(gè)遺址 發(fā)現(xiàn)的最酷的化石。

05:50

(Laughter)

（笑聲）

05:51

The assemblage consists of 190 whole or fragmentary teeth that range in age from very old to very young. Like the skeletons, the teeth present a mix of primitive and derived traits. In modern humans, the third molar is typically the smallest, while the first molar is the biggest, but Homo naledi has the primitive condition where the third molar is the biggest and the first molar is the smallest. The anterior teeth, or the incisors and canines, are small for the genus Homo, and the lower canine has a cuspulid on it -- an extra cuspule that gives it a distinct mitten-like shape that it shares with some specimens of the early human, Homo erectus. The overall shape of the teeth looked odd to me, so I performed crown-shape analysis on the occlusal surfaces of deciduous teeth, or baby teeth -- on your left -- and the permanent premolars and molars on your right. The deciduous teeth are especially narrow, and the premolars are unique in their outline shape compared to other hominids.

這組化石包括190顆整牙和牙齒碎片, 它們的年齡跨度從高齡到低齡。 就像這具骨骼， 它的牙齒呈現(xiàn)出原始和演化的特征。 現(xiàn)代人的牙齒中， 第三顆磨牙的特征就是 最小的，而第一顆卻是最大的， 但是奈勒迪人牙齒的基本特征是： 第三顆磨牙是最大的，而第一顆是最小的。 人類(lèi)前面的牙齒， 也叫門(mén)齒和犬齒， 是很小的， 并且下犬齒有齒尖—— 那是一個(gè)明顯像手套一樣的額外的牙尖。 一些早期人類(lèi)和直立人的 標(biāo)本上都有這個(gè)特點(diǎn)。 我覺(jué)得這些牙齒形狀看起來(lái)很奇怪， 所以我在這個(gè) 乳牙的咬合表面分析了牙冠-形狀—— 左側(cè)的-—— 還有右側(cè)的恒牙前齒和磨牙。 這些乳牙的輪廓格外狹窄。 和其他人種相比， 這些前齒的輪廓非常特別。

07:00

In fact, when I compare the outlines, when I lay them on top of each other, they look very similar. We say they have "low intraspecific variations," so the variation within the species is low. When I compare this to groups like the australopithecines, the intraspecific variation is much larger.

事實(shí)上，當(dāng)我比較它們的輪廓時(shí)， 當(dāng)我把一副牙骨放在另一副上， 它們看上去非常相似。 我們說(shuō)它們具有“低物種內(nèi)多樣性” 也就是說(shuō)，在同一物種內(nèi)，變化較少。 當(dāng)我們把它們和一些類(lèi)似 南方古猿的群體進(jìn)行對(duì)比時(shí)， 物種內(nèi)的多樣性就大得多。

07:20

Postcranially, the team concluded that the position of the shoulders suggesting naledi was a climber; the flared pelvis and curved fingers are all primitive for the genus Homo. On the other hand, the humanlike wrist, long slender legs and modern feet are all consistent with other members of the genus.

關(guān)于顱下結(jié)構(gòu)，小組得出的結(jié)論是， 肩部的位置說(shuō)明奈勒迪人擅長(zhǎng)攀爬； 寬闊的骨盆和彎曲的手指 都屬于遠(yuǎn)古人的特征。 另一方面， 和人類(lèi)相似的腰部和足部，修長(zhǎng)的雙腿 都和其他人種類(lèi)似。

07:42

In 2017, we announced more specimens of Homo naledi from the nearby Lesedi Chamber, also in the Rising Star cave system. In addition, our geology team managed to produce an age estimate. The date's a big deal because, up until now, we had based our analysis solely on the morphology of the specimens, without previous knowledge of how old something is -- something which could unconsciously bias our interpretations. With its small brain and flared pelvis, we would not have been surprised if the fossils turned out to be two million years old. Instead, the fossils dated to 235 to 336 thousand years, an incredibly young date for such a small-brained individual.

2017年，我們公布了更多的奈勒迪人樣本。 它們是在Lesedi Chamber旁邊發(fā)現(xiàn)的， 這個(gè)地方也屬于瑞星洞系。 另外，我們的地質(zhì)小組 設(shè)法做出了一個(gè)年代估算。 數(shù)據(jù)非常重要，因?yàn)槟壳盀橹梗?我們的分析僅僅是基于人類(lèi)標(biāo)本。 沒(méi)有對(duì)年代判斷的基本知識(shí)， 也許有意無(wú)意中，我們的理解會(huì)有失偏頗。 看這個(gè)小小的頭骨和寬闊的骨盆， 如果早知道它們?cè)瓉?lái) 已經(jīng)有200萬(wàn)年歷史了， 我們就不會(huì)如此驚訝了。 其實(shí)，這些化石可以追溯到 23.5-33.6萬(wàn)年前。 對(duì)這么小的頭骨來(lái)說(shuō)， 這個(gè)年代太新，令人難以置信。

08:29

So think back to what I said earlier: we thought that our brains were becoming larger relative to the rest of our body. Now we have a small-brained, young individual complicating this idea. What does all this mean?

想一想我剛才說(shuō)過(guò)的： 我們以為相對(duì)于身體的其他部位 而言，我們的大腦正在變大。 現(xiàn)在這個(gè)大腦體積小，年代很新的 標(biāo)本讓這件事復(fù)雜起來(lái)。 這都意味著什么呢？

08:44

Homo naledi has taught us that we need to reassess what it means to be in the genus Homo. We need to rethink what it means to be human. In fact, most of the characteristics that we use to define the genus Homo, such as brain size and hip morphology, are no longer valid. No other species exists with this mix of primitive and derived traits. Why is there so much morphological variation in the genus Homo? And what force is driving that variation?

奈勒迪人給了我們一個(gè)啟示， 我們需要重新測(cè)評(píng)什么是人屬。 我們需要重新思考什么是人類(lèi)。 實(shí)際上，大多數(shù)我們 用來(lái)定義人屬的那些特征， 比如大腦尺寸和臀部形態(tài)， 都已經(jīng)不再有效了。 沒(méi)有哪個(gè)物種混合著 既原始又衍生的特點(diǎn)。 為什么會(huì)有這么多形態(tài)各異的人屬？ 又是什么促進(jìn)了這種多樣性的呢？

09:14

Another implication for these fossils is that for the first time, we have concrete evidence of a species coexisting in Africa, at 300,000 years, with modern humans. Until this discovery, we only had large-brained modern humans that existed in Africa. Did they interbreed with each other? Did they compete with each other?

這些化石的另外一些影響是，它第一次 提供了確鑿的證據(jù)說(shuō)明了 30萬(wàn)年前非洲的物種和 現(xiàn)代人類(lèi)的共生關(guān)系。 這次發(fā)現(xiàn)之前， 我們以為只有大腦體積較大的 現(xiàn)代人在非洲存在過(guò)。 他們之間是否雜交過(guò)？ 他們是否相互競(jìng)爭(zhēng)？

09:38

Another implication that these fossils have is for the archaeologists studying stone tools in South Africa. Keep in mind that neither the Dinaledi nor the Lesedi Chambers have any artifacts in them. However, they do overlap in time with several stone-tool industries, the makers of which are considered to be either modern humans or direct human ancestors. This begs the question: Who made the stone tools of South Africa? Brain size has historically played a key role in identifying a species as a tool user. The idea is that you need to have a large brain to have even the capacity to make stone tools. But that notion has been questioned. Furthermore, Homo naledi, even with its small brain size, has a hand-wrist morphology similar to other species that did make and use stone tools, suggesting it had the capability. With two species coexisting in Africa at 300,000 years, we can no longer assume we know the maker of tools at sites with no associated species.

另外一個(gè)意義是，這些化石 給考古學(xué)家提供了 研究非洲石器時(shí)代的機(jī)會(huì)。 別忘了既不是Dinaledi， 也不是Lesedi Chambers 才擁有史前古器物。 然而，他們的幾個(gè)石器工業(yè)時(shí)代 在某些時(shí)候是重合的， 它們上面的標(biāo)記被認(rèn)為要么是現(xiàn)代人的， 要么是人類(lèi)祖先的。 這就引出了一個(gè)問(wèn)題： 誰(shuí)制造了南非的史前石器？ 歷史上，大腦的體積在界定物種的時(shí)候 起到了重要作用。 這個(gè)概念說(shuō)明，只有擁有較大的大腦， 你才具備制造石器的能力。 但是我們開(kāi)始懷疑這個(gè)概念了。 進(jìn)一步說(shuō)，奈勒迪人雖然大腦體積小， 手腕形狀卻和 其他制造工具的物種類(lèi)似， 說(shuō)明它也具備同樣的能力。 考慮到這兩種物種在非洲共生了30萬(wàn)年， 我們不能再假定我們知道，在遺址上的 工具制造者和別的物種沒(méi)有關(guān)聯(lián)。

10:43

So where does Homo naledi fit in our human evolutionary lineage? Who is it most closely related to? Who did it evolve from? We're still trying to figure all that out. It's ironic, because paleoanthropologists are renowned for having small sample sizes. We now have a large sample size, and more questions than answers. Homo naledi has taught us, has brought us a little bit closer to better understanding our evolutionary past. So while Mrs. Ples will always hold a special place in my heart, she now shares that space with several thousand others.

那么，奈勒迪人應(yīng)該在 人類(lèi)進(jìn)化線上哪個(gè)位置上呢？ 它最接近誰(shuí)呢？ 它從什么物種進(jìn)化而來(lái)？ 我們?nèi)匀辉趯ふ掖鸢浮?這很諷刺，因?yàn)楣湃祟?lèi)學(xué)家 以擁有少量的標(biāo)本著稱。 我們現(xiàn)在有大量的標(biāo)本， 問(wèn)題卻比答案更多了。 奈勒迪人給了我們啟示， 帶我們更進(jìn)一步 理解我們的進(jìn)化史。 因此我心中將會(huì)一直留有 普勒斯太太的角色， 她現(xiàn)在正在和成千上萬(wàn)的 人分享這個(gè)角色。

11:16

(Laughter)

（笑聲）

11:18

Thank you.

謝謝。

11:19

(Applause)

（掌聲）