ABOUT THE SPEAKER
Tara Djokic - Astrobiologist
Tara Djokic discovered direct evidence that indicates some of Earth's oldest life once thrived in hot springs on land.

Why you should listen

Tara Djokic observes the world through the lens of geology and astrobiology. During her studies as a geology graduate student, she discovered direct evidence that indicates some of Earth's oldest life once thrived in hot springs on land -- pushing back the record of land-based hot springs on Earth by approximately three billion years and supporting Darwin's theory that life may have started in some "warm little pond." Djokic's discoveries have also been used to help guide the search for life elsewhere in our solar system. She was involved in the third and fourth "Site Selection Workshops" for the NASA Mars2020 Rover, which is due to launch in July-August, 2020.

Djokic's scientific passions are equal to her passion for sharing knowledge. During her graduate studies, she designed and developed an immersive virtual field trip (VFT) that has been used to teach astrobiology at UNSW Sydney since 2016. Her geological research also led to her involvement in the IMAX documentary The Story of Earth, which (as its title suggests) illustrates Earth's approximately 4.6-billion-year history. She is a seeker of knowledge and believes all people should be encouraged to be curious about our world.

More profile about the speaker
Tara Djokic | Speaker | TED.com
TEDxSydney

Tara Djokic: This ancient rock is changing our theory on the origin of life

塔拉·德约基奇: 这块古老的岩石正在改变生命起源理论

Filmed:
1,892,611 views

地球生命究竟从何时何地起源?长期以来,科学家一直认为生命是 30 亿年前在海洋中出现的——直到天体生物学家塔拉·德约基奇(Tara Djokic)和她的团队在澳大利亚西部沙漠中的意外发现。来了解一下热火山池附近发现的古老岩石如何改变我们对生命起源之谜的理解。
- Astrobiologist
Tara Djokic discovered direct evidence that indicates some of Earth's oldest life once thrived in hot springs on land. Full bio

Double-click the English transcript below to play the video.

00:13
The Earth地球 is 4.6 billion十亿 years年份 old,
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地球的寿命有46亿年,
但人类的寿命还不到100年。
00:17
but a human人的 lifetime一生 often经常 lasts持续
for less than 100 years年份.
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00:23
So why care关心 about
the history历史 of our planet行星
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那我们为什么要关心地球历史呢,
它那么遥远,好像
与我们的生活完全无关。
00:26
when the distant遥远 past过去 seems似乎
so inconsequential无关紧要 to everyday每天 life?
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00:32
You see, as far as we can tell,
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就我们所知,
在太阳系里,只有地球
00:34
Earth地球 is the only planet行星
in our solar太阳能 system系统
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拥有灿烂的生命,
00:38
known已知 to have sparked引发 life,
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也只有地球能提供
让人类存活的环境。
00:40
and the only system系统 able能够 to provide提供
life support支持 for human人的 beings众生.
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00:46
So why Earth地球?
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为什么偏偏是地球?
00:48
We know Earth地球 is unique独特
for having plate盘子 tectonics构造,
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我们知道地球是独一无二的,
它有板块构造、
表面有液体水、
00:52
liquid液体 water on its surface表面
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还有富含氧气的大气层。
00:53
and an oxygen-rich富氧 atmosphere大气层.
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00:56
But this has not always been the case案件,
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但并不是一直这样,
因为古岩石记录了地球演化过程中
00:58
and we know this because ancient rocks岩石
have recorded记录 the pivotal关键的 moments瞬间
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的每个关键时刻。
01:03
in Earth's地球 planetary行星 evolution演化.
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01:07
And one of the best最好 places地方
to observe those ancient rocks岩石
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观察古岩石的最佳去处之一,
是澳大利亚西部的皮尔布拉。
01:10
is in the Pilbara皮尔巴拉 of Western西 Australia澳大利亚.
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01:15
The rocks岩石 here are 3.5 billion十亿 years年份 old,
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这里的岩石存在了 35 亿年之久,
其中藏着地球上
最早期生命的证据。
01:20
and they contain包含 some of the oldest最老的
evidence证据 for life on the planet行星.
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01:25
Now, often经常 when we think of early life,
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通常,说起古生命时,
我们想到的是剑龙,
01:27
we might威力 imagine想像 a stegosaurus石龙
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或者一种鱼爬到了陆地上。
01:30
or maybe a fish crawling爬行 onto land土地.
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01:35
But the early life that I'm talking about
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但我说的古生命,
是简单微生物,比如细菌。
01:37
is simple简单 microscopic显微 life, like bacteria.
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01:41
And their fossils化石 are often经常 preserved罐头
as layered分层 rock structures结构,
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它们的化石通常是层叠的岩石结构,
称为叠层石。
01:45
called stromatolites叠层石.
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01:48
This simple简单 form形成 of life
is almost几乎 all we see in the fossil化石 record记录
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地球出现生命的前 30 亿年里,
化石记录中几乎只能见到
这种简单的生命形式。
01:53
for the first three billion十亿 years年份
of life on Earth地球.
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01:58
Our species种类 can only be traced追踪
back in the fossil化石 record记录
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在化石记录中寻找人类的踪迹,
只能追踪到几万年前。
02:01
to a few少数 hundred thousand years年份 ago.
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从化石记录中我们了解到,
02:04
We know from the fossil化石 record记录,
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细菌生命开始得很早,
02:06
bacteria life had grabbed抓起
a strong强大 foothold立足
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大约 35 至 40 亿年前就存在了。
02:10
by about 3.5 to four billion十亿 years年份 ago.
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02:14
The rocks岩石 older旧的 than this
have been either destroyed销毁
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而比这个时间更久的岩石,
要么被破坏了,
要么随板块运动过度变形。
02:17
or highly高度 deformed变形
through通过 plate盘子 tectonics构造.
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02:21
So what remains遗迹 a missing失踪
piece of the puzzle难题
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所以遗留下来一个
待解决的难题就是,
地球上的生命到底是
什么时间开始的。
02:24
is exactly究竟 when and how
life on Earth地球 began开始.
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02:31
Here again is that ancient
volcanic火山 landscape景观 in the Pilbara皮尔巴拉.
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回到皮尔布拉的古火山地貌。
02:35
Little did I know that our research研究 here
would provide提供 another另一个 clue线索
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我当时完全不知道,我们在这里
的研究会给生命起源之谜
提供另一个线索。
02:39
to that origin-of-life生命起源 puzzle难题.
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02:42
It was on my first field领域 trip here,
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那是我第一次到这里实地考察,
在整整一周的地图绘制项目
快要结束时,
02:45
toward the end结束 of a full充分,
long week mapping制图 project项目,
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我发现了一件不寻常的东西。
02:49
that I came来了 across横过 something
rather special特别.
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02:53
Now, what probably大概 looks容貌 like
a bunch of wrinkly old rocks岩石
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这一堆纹路横生的石头,
其实是叠层石。
02:56
are actually其实 stromatolites叠层石.
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在这一堆的中间,是一块
小小的罕见的岩石,
02:58
And at the center中央 of this mound
was a small, peculiar奇特 rock
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像小孩的手那么大。
03:02
about the size尺寸 of a child's孩子的 hand.
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03:06
It took six months个月 before we inspected检查
this rock under a microscope显微镜,
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我们花了六个月才得以
在显微镜下观察它,
当时我的一位老师,
马尔科姆·沃尔特,
03:11
when one of my mentors导师
at the time, Malcolm马尔科姆 Walter沃尔特,
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提出这石头像硅华。
03:13
suggested建议 the rock resembled相似 geyserite盖塞里特.
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03:18
Geyserite盖塞里特 is a rock type类型 that only forms形式
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硅华是一种岩石类型,它的形成地
只在热泉池里面和边缘周围。
03:21
in and around the edges边缘
of hot spring弹簧 pools.
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03:26
Now, in order订购 for you to understand理解
the significance意义 of geyserite盖塞里特,
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为了让各位理解硅华的重要,
我要带大家回到十九世纪。
03:29
I need to take you back
a couple一对 of centuries百年.
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03:35
In 1871, in a letter
to his friend朋友 Joseph约瑟夫 Hooker妓女,
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1871年,查尔斯·达尔文在信中
对他的朋友约瑟夫·虎克说:
03:39
Charles查尔斯 Darwin达尔文 suggested建议:
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03:42
"What if life started开始
in some warm little pond池塘
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“如果生命是在一些
温暖的小池塘里诞生呢——
池塘里有各种化学物质,
03:45
with all sort分类 of chemicals化学制品
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已准备好进行更复杂的进化呢?”
03:48
still ready准备 to undergo经历
more complex复杂 changes变化?"
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03:52
Well, we know of warm little ponds池塘.
We call them "hot springs弹簧."
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我们知道这些温暖
的小池塘指的是“温泉”。
在这类环境中,有热水,
03:55
In these environments环境, you have hot water
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从底下的岩石里溶解出矿物质。
03:58
dissolving溶解 minerals矿物质
from the underlying底层 rocks岩石.
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04:02
This solution mixes混合 with organic有机 compounds化合物
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这种液体与有机化合物混合,
形成了某种化学环境,
04:07
and results结果 in a kind of chemical化学 factory,
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而研究人员已证明这种化学环境
可以产生简单的细胞结构,
04:10
which哪一个 researchers研究人员 have shown显示
can manufacture制造 simple简单 cellular细胞的 structures结构
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这种细胞结构就是
迈向生命起源的第一步。
04:16
that are the first steps脚步 toward life.
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但达尔文写出这封信
之后的一百年,
04:19
But 100 years年份 after Darwin's达尔文 letter,
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海洋里发现了
深海热液喷口,即热泉。
04:21
deep-sea深海 hydrothermal热液 vents通风口, or hot vents通风口,
were discovered发现 in the ocean海洋.
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这些也是化学环境。
04:25
And these are also chemical化学 factories工厂.
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这一个位于太平洋海平面以下
04:28
This one is located位于 along沿
the Tonga汤加 volcanic火山 arc,
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1100 米的汤加火山弧。
04:31
1,100 meters below下面 sea level水平
in the Pacific和平的 Ocean海洋.
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04:37
The black黑色 smoke抽烟 that you see billowing滚滚
out of these chimneylike烟囱状 structures结构
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从这些烟囱一样的结构里
飘出的“黑烟”,
也是富含矿物质的液体,
04:41
is also mineral-rich矿藏丰富 fluid流体,
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是细菌的食物来源。
04:43
which哪一个 is being存在 fed美联储 off by bacteria.
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04:46
And since以来 the discovery发现
of these deep-sea深海 vents通风口,
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自从发现了这些深海热泉,
生命起源地的说法就聚焦在海洋。
04:49
the favored青睐 scenario脚本 for an origin起源 of life
has been in the ocean海洋.
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04:54
And this is for good reason原因:
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这是很合理的:
04:57
deep-sea深海 vents通风口 are well-known知名
in the ancient rock record记录,
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深海热泉在古岩石记录中很常见,
通常认为地球早期
整体被海洋覆盖,
05:00
and it's thought that the early Earth地球
had a global全球 ocean海洋
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陆地表面极少。
05:03
and very little land土地 surface表面.
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所以,地球最初拥有大量深海热泉,
05:06
So the probability可能性 that deep-sea深海 vents通风口
were abundant丰富 on the very early Earth地球
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与之非常符合的情况是
05:11
fits适合 well with an origin起源 of life
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生命在海洋里起源。
05:13
in the ocean海洋.
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05:16
However然而 ...
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但是——
05:18
our research研究 in the Pilbara皮尔巴拉
provides提供 and supports支持
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我们在皮尔巴拉的研究给出了
另一种视角和证据。
05:22
an alternative替代 perspective透视.
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05:25
After three years年份, finally最后, we were
able能够 to show显示 that, in fact事实,
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三年后,我们终于能证明,实际上,
这块小石头就是硅华。
05:31
our little rock was geyserite盖塞里特.
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这个结论说明,
不仅皮尔巴拉有 35 亿年历史
05:34
So this conclusion结论 suggested建议
not only did hot springs弹簧 exist存在
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的火山里有温泉,
05:39
in our 3.5 billion-year-old十亿岁
volcano火山 in the Pilbara皮尔巴拉,
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而且意味着,在地球的地质记录中,
05:43
but it pushed back evidence证据 for life
living活的 on land土地 in hot springs弹簧
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生命在陆地的热泉中存活的证据,
05:49
in the geological地质 record记录 of Earth地球
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向前推了 30 亿年。
05:51
by three billion十亿 years年份.
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05:56
And so, from a geological地质 perspective透视,
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所以,从地质角度来看,
达尔文说的小池塘
是合理的生命起源地。
06:00
Darwin's达尔文 warm little pond池塘
is a reasonable合理 origin-of-life生命起源 candidate候选人.
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06:09
Of course课程, it's still debatable值得商榷
how life began开始 on Earth地球,
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当然,地球生命起源
的方式仍有待探讨,
也许可以永远争论下去。
06:12
and it probably大概 always will be.
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但有一点很清楚,
生命已经蓬勃发展起来;
06:15
But it is clear明确 that it's flourished蓬勃发展;
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它变得多样了,
06:17
it has diversified多元化,
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还越来越复杂。
06:19
and it has become成为 ever more complex复杂.
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最终,到达了人类的时代,
06:21
Eventually终于, it reached到达
the age年龄 of the human人的,
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人类这个物种开始质疑自身的存在,
06:25
a species种类 that has begun开始
to question its own拥有 existence存在
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也质疑外星球生命的存在:
06:28
and the existence存在 of life elsewhere别处:
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06:32
Is there a cosmic宇宙的 community社区
waiting等候 to connect with us,
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有宇宙联盟要与我们联系吗,
还是宇宙只有人类孤单存在?
06:35
or are we all there is?
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06:38
A clue线索 to this puzzle难题 again
comes from the ancient rock record记录.
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关于这个问题的线索
再次出现在古岩石记录中。
06:44
At about 2.5 billion十亿 years年份 ago,
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大约 25 亿年前,
有证据表明,
细菌已经开始产生氧气,
06:46
there is evidence证据 that bacteria
had begun开始 to produce生产 oxygen,
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有点像现在的植物产生氧气。
06:51
kind of like plants植物 do today今天.
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地质学家把随后的那段时期
06:53
Geologists地质学家 refer参考 to
the period that followed其次
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称为“大氧化事件”。
06:56
as the Great Oxidation氧化 Event事件.
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06:59
It is implied默示 from rocks岩石
called banded带状 iron formations编队,
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这一推测是从称为
带状铁形成区的岩石里得出的,
这种层层堆叠的岩石大多几百米厚,
07:04
many许多 of which哪一个 can be observed观察到的 as
hundreds-of-meter-thick数百米厚 packages of rock
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位于澳大利亚西部,
07:09
which哪一个 are exposed裸露 in gorges峡谷
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在横穿卡瑞吉尼国家公园的
07:11
that carve雕刻 their way through通过
the Karijini卡里吉尼 National国民 Park公园
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峡谷里可以看到。
07:14
in Western西 Australia澳大利亚.
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07:17
The arrival到达 of free自由 oxygen allowed允许
two major重大的 changes变化 to occur发生 on our planet行星.
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游离氧的到来让我们的星球
发生了两个重大变化。
首先,氧气让复杂生命得以进化。
07:21
First, it allowed允许 complex复杂 life to evolve发展.
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生命需要氧气来变大、变复杂。
07:25
You see, life needs需求 oxygen
to get big and complex复杂.
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07:29
And it produced生成 the ozone臭氧 layer,
which哪一个 protects保护 modern现代 life
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氧气还制造了臭氧层,
它保护现代生命
不受阳光中波紫外线辐射的伤害。
07:32
from the harmful有害 effects效果
of the sun's太阳 UVBUVB radiation辐射.
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07:36
So in an ironic具有讽刺意味 twist, microbial微生物 life
made制作 way for complex复杂 life,
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讽刺的是,微生物
艰难进化成复杂生命,
在这颗星球上耗费了
07:41
and in essence本质, relinquished放弃
its three-billion-year30亿年 reign统治
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30 亿年的时光。
07:45
over the planet行星.
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07:47
Today今天, we humans人类 dig up
fossilized化石 complex复杂 life
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今天,我们人类把变成化石的
复杂生命挖出来,
把它们当燃料烧掉。
07:50
and burn烧伤 it for fuel汽油.
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07:53
This practice实践 pumps vast广大 amounts
of carbon dioxide二氧化碳 into the atmosphere大气层,
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这种行为会释放出
大量二氧化碳到大气,
就像我们的微生物祖先一样,
07:57
and like our microbial微生物 predecessors前辈,
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我们已经开始让这颗星球
发生了重大变化。
08:00
we have begun开始 to make
substantial大量的 changes变化 to our planet行星.
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08:04
And the effects效果 of those
are encompassed包含 by global全球 warming变暖.
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这些改变的结果包括全球变暖。
08:10
Unfortunately不幸, the ironic具有讽刺意味 twist here
could see the demise让位 of humanity人性.
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不幸的是,这个讽刺
会指向人类的终结。
08:16
And so maybe the reason原因
we aren't connecting with life elsewhere别处,
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也许我们联系不到外星生物、
联系不到外星智慧生物的原因,
08:20
intelligent智能 life elsewhere别处,
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是一旦智慧生物进化了,
08:22
is that once一旦 it evolves演变,
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就会很快自取灭亡。
08:24
it extinguishes itself本身 quickly很快.
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08:28
If the rocks岩石 could talk,
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如果岩石能说话,
我感觉它们会说:
08:30
I suspect疑似 they might威力 say this:
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08:34
life on Earth地球 is precious珍贵.
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地球上的生命是宝贵的。
08:38
It is the product产品 of
four or so billion十亿 years年份
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它的诞生用了大约 40 亿年,
经历了生命与地球之间
08:43
of a delicate精巧 and complex复杂 co-evolution协同进化
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精细复杂的共同进化,
08:47
between之间 life and Earth地球,
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而人类只在这 40 亿年
的最后一瞬间存在过。
08:50
of which哪一个 humans人类 only represent代表
the very last speck斑点 of time.
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08:57
You can use this information信息
as a guide指南 or a forecast预测 --
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这些信息可以为你
提供指引或预测——
或者说是解释,为什么
银河系的地球如此孤单。
09:01
or an explanation说明 as to why it seems似乎
so lonely孤独 in this part部分 of the galaxy星系.
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09:08
But use it to gain获得 some perspective透视
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但是,通过这些信息多想想吧,
09:13
about the legacy遗产 that you
want to leave离开 behind背后
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在这个我们称为家园的星球上,
人类要留下些什么。
09:17
on the planet行星 that you call home.
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09:24
Thank you.
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谢谢你们。
(掌声)
09:25
(Applause掌声)
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Translated by Yan Gao

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ABOUT THE SPEAKER
Tara Djokic - Astrobiologist
Tara Djokic discovered direct evidence that indicates some of Earth's oldest life once thrived in hot springs on land.

Why you should listen

Tara Djokic observes the world through the lens of geology and astrobiology. During her studies as a geology graduate student, she discovered direct evidence that indicates some of Earth's oldest life once thrived in hot springs on land -- pushing back the record of land-based hot springs on Earth by approximately three billion years and supporting Darwin's theory that life may have started in some "warm little pond." Djokic's discoveries have also been used to help guide the search for life elsewhere in our solar system. She was involved in the third and fourth "Site Selection Workshops" for the NASA Mars2020 Rover, which is due to launch in July-August, 2020.

Djokic's scientific passions are equal to her passion for sharing knowledge. During her graduate studies, she designed and developed an immersive virtual field trip (VFT) that has been used to teach astrobiology at UNSW Sydney since 2016. Her geological research also led to her involvement in the IMAX documentary The Story of Earth, which (as its title suggests) illustrates Earth's approximately 4.6-billion-year history. She is a seeker of knowledge and believes all people should be encouraged to be curious about our world.

More profile about the speaker
Tara Djokic | Speaker | TED.com