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新冠期间三大科学发现

Three MORE Things You Missed Because of COVID

[音乐]
Another year of the pandemic has come and gone.
全球性疫情又过去一年
A lot of science news this year has been focused on the vaccines,
今年 许多科学新闻关注疫苗研发
new variants, and the rest of our ongoing collective misfortune.
病毒新变体 以及当下全球共同经历的其他不幸
But science has carried on —
但是科学仍在进步–
and there have been plenty of amazing discoveries
除新冠病毒方面的研究外
this year that had nothing to do with COVID.
今年还有很多新的惊奇发现
We think they deserve the spotlight too,
我们认为这些发现也值得关注
so here are three science stories you might have missed this year.
所以接下来向大家介绍 今年我们有可能会忽略的三大科学发现
Since the 1980s, scientists have been pretty sure that dinosaurs died out
20世纪80年代以来 科学家们一直都非常确信
during a mass extinction event caused by a roughly 10 kilometer meteorite
恐龙是在 6600 万年前一颗大约 10 公里长的陨石
hitting the Earth’s surface around 66 million years ago.
撞击地球表面造成的大规模灭绝事件中灭绝的
We’ve even found the likely scene of the crime:
我们甚至找到了可能的撞击现场:
a crater about 180 to 200 kilometers
直径180到200千米长的陨石坑
in diameter on the Yucatan peninsula of Mexico, called Chicxulub.
即墨西哥尤卡坦半岛的希克苏鲁伯陨石坑
But where that meteorite came from has continued to be a puzzle.
但这颗陨石的来源地还是个谜
It came from space, but we’re trying to be more specific than that.
知道它从外太空来 但是我们试图更具体一些
We know from studying the crater that the object was likely
我们研究石坑 发现陨石可能是
made up of carbon along with other elements
碳和其他元素所构成
Previous research had pointed to the breakup of the Baptistina asteroid family.
之前的研究指出 它是巴普提斯蒂娜行星族群的解体
So, it would be one of 2500 smaller asteroids that formed
所以这颗陨石可能是2500万颗小行星中的一颗
after a large asteroid broke up 160 million years ago.
这些小行星在一亿六千万年前是一颗大行星解体形成的
But the Baptistina asteroids were made of iron and magnesium silicates.
但是巴普提斯蒂娜小行星群是由铁和硅酸镁组成
Also, the timing of the Baptistina breakup didn’t quite fit.
而且小行星群解体时间也不太吻合
The other option was that it was just a normal background asteroid
另一个解释说它是一个普通的次要小行星
that just happened to hit the Earth.
碰巧撞上地球
But mathematically, an asteroid from the main asteroid belt made out of carbon
但数学上来看 来自主小行星带上的由碳构成的小行星
is only going to hit Earth once every 3.5 billion years,
只将会每35亿年撞击一次地球
which would be basically once in the entire history of life.
整个地球生命史中 基本上只会发生一次
Now, comets are more likely to be carboniferous.
目前 彗星更有可能是含碳的
But a comet the right size hitting Earth is even less frequent,
但大小匹配的彗星撞击地球的频率更低
like once every 4 to 11 billion years.
40到110亿年一次
So, it’s been a pretty weird mystery.
所以陨石的来源地是个相当古怪的谜
But this year, astronomers at Harvard did the math and realized that
但今年 哈佛的天文学家通过数学计算发现
a carboniferous comet from the edge of the solar system
太阳系边缘含碳的彗星
could have been knocked off course by Jupiter,
可能被木星引力影响脱离了轨道
changing its orbit and sending it toward the sun.
甚至改变了轨道 朝太阳推进
When it got close to the sun, gravitational forces could have broken it apart,
当它靠近太阳 万有引力致使它分解
sending pieces flying into Earth’s orbital path.
使碎片飞入地球轨道
And the more objects crossing into Earth’s orbit,
所以进入地球轨道的碎片越多
the more likely one is to actually hit the Earth.
就越有可能撞上地球
Sure enough, their model predicts carboniferous objects threatening Earth
果然 他们的模型推测 含碳彗星撞击地球
at just about the right time and frequency to have made the Chicxulub crater.
恰好在匹配的时间 以合理的频率形成了希克苏鲁伯陨石坑
This is also consistent with other carboniferous impact craters
这也与南非和哈萨克斯坦的
in South Africa and Kazakhstan.
其他石碳系撞击坑一致
So these astronomers might have actually figured out
因此 这些天文学家可能实际上已经发现了
where the comet that killed the dinosaurs came from.
致使恐龙灭绝的彗星从哪里来的
And 2021 wasn’t just a big year for ancient critters.
而且2021年 不仅仅在古代动物方面有重大发现
It was also a big year for ancient art.
在古代艺术品方面也成绩斐然
Several discoveries this year brought us
今年的一些发现揭示了
some of the earliest known examples of hominin art.
一些已知的最早古人类艺术品
In Israel, archaeologists discovered a wild ox bone
考古学家在以色列发现一个12万年前
with six nearly parallel incisions dating back 120,000 years.
有着六条几乎平行切痕的野牛骨头
Now, I know that a bone with straight lines carved into it may not seem like art,
在现代 一块刻有直线条的骨头可能称不上艺术品
but anthropologically, it’s a reflection of what’s called symbolic mediated behavior.
但从人类学角度来看 这反应出一种被称为“象征中介行为”的做法
These are practices where something takes on a meaning more than just
在这些通常的做法中 物品所体现出来的 不再是
functional use that depends on collectively shared beliefs.
功能上的用途 而是一种由集体信仰所决定的意义
Funeral practices, decorative jewelry or clothing,
葬礼习俗 装饰珠宝或服饰
cave painting, and engraving are all considered symbolic behaviors.
洞穴壁画和雕刻 都被认为是象征性的行为
These practices are important in human history,
这些行为在人类历史中十分重要
because they reflect the development of organized thinking
因为它们反映出族群内部成员间
and communication between members of a group.
有组织的思想和交流的发展
Now, the researchers can’t say for sure what the incisions mean,
目前 研究者还没法肯定这些雕刻的含义
because they don’t match any previously discovered patterns.
因为他们和之前发现的图案都不匹配
But whatever it represented,
但是无论这个骨头代表着什么
this bone is the oldest known example of symbolic representation from the Middle East,
它都是已知的 中东最古老的象征符号代表
suggesting that collective symbolic
这表明集体象征意义在这个地区
meaning developed in the region earlier than scientists had thought.
的发展比科学家们料想的要早
And in the Tibetan Plateau, archaeologists discovered the oldest
考古学家在青藏高原发现已知的最古老艺术
known art made on an immobile rock surface.
这种艺术是在不动的岩石表面完成的
They found impressions of hand- and footprints made in soft limestone
他们发现软石灰岩上的手印和脚印
that dated back to between 169,000 and 226,000 years.
这些印迹可以追溯到16万9千到22万6千年间
They were able to rule out
他们可以断定
that the handprints ended up there through everyday movement
这些手印不是日常生活留下来的
or from someone using their hands to stabilize themselves.
或者有人用手来保持平衡而留下的
The impressions were made intentionally.
其实这些痕迹是故意留下的
And what’s more, they were made by children.
并且是孩子留下的
That’s right, these are basically the 200,000 year old version
没错 说白了 这些就是20万年前远古版本的
of the concrete stepping stone with your handprint in it
父母家后院有你手掌印的
that is still in your parents’ backyard.
混凝土垫脚石
If that’s not adorable, I don’t know what is.
如果这都不可爱 那我不知道什么才可爱
Before this discovery,
在此之前
the oldest handprint art was paintings that used hands as stencils
最古老的手印艺术是用手做模板的绘画
dating back 40,000 years, and these impressions are way older than that.
绘画可追溯至4万年前 而新发现的手印比这还要古老得多
And maybe more importantly,
更重要的是
it may reflect that the earliest artists were actually kids,
这可能表明最早的艺术家实际上是孩子
or at least that kids of the time may have used art
或者至少那个时代的孩子在玩的时候
and creative expression when they played.
可能会使用艺术和创造性的表达方式
Ancient hominins. They’re just like us!
古人类也和我们一样啊
And we didn’t just learn about modern human development this year.
今年我们不仅仅学到了现代人类的发展
We also learned more broadly about mammal development.
也更广泛地了解了哺乳动物的发展
Traditionally, somewhere between 20% and 92% of our DNA
传统上认为 大约20%到92%之间的DNA
has been thought of as non-functional.
是没有功能的
It’s often been maligned as “junk DNA”.
通常被诽谤为“垃圾DNA”
And the junkiest of our DNA are transposons,
DNA中最垃圾无用的是转座子
also called transposable elements, or TEs.
也叫作转座元素 简称TEs
These segments of DNA make up around 50% of the human genome.
这些DNA片段约占人类基因组的50%
They jump around to different places on the genome,
它们在基因组上的不同位置跳跃
and as far as we’ve known for a long time,
在人们长期看来
they don’t do much else except sometimes cause problems when they land.
它们除了着陆时偶尔会引起问题外 不会做太多其他事情
A few transposable elements have taken on new, more helpful functions over time,
随着时间的推移 一些转座因素已经开始具有新的更有用的功能
helping to determine how and when other parts of the genome get used.
帮助确定如何和何时使用基因组的其他部分
But it’s not totally clear if that regulation is helpful, or hurtful,
但是这种调节是有益还是有害 或者没啥影响
or even makes any difference at all.
这些都还不完全清楚
So this year, scientists took a closer look at a specific TE.
所以今年 科学家进一步研究了一种特定的转座元素
It’s known to regulate the expression of a gene called Cdk2ap1.
它可以调节Cdk2ap1基因的表达
That gene is involved in embryonic cell replication,
该基因参与胚胎细胞复制
and when and how embryos implants in the uterus.
影响胚胎在子宫着床的时间和方式
They bred some mice that had the gene, but were missing the TE regulating it.
他们培育了一些带有该基因的老鼠 但缺少可调节它的转座元素
And half of the resulting mouse pups died at birth.
结果有一半的幼鼠在出生时死亡
Normally, Cdk2ap1 becomes more active around 24 hours before embryo implantation.
Cdk2ap1一般在胚胎着床前约24小时左右变得更活跃
When that gene isn’t working, embryos can’t implant correctly,
当它不运作时 胚胎就没法正确着床
causing serious complications for the parent and offspring.
这会给父母和后代造成严重的并发症
Now, other mammals don’t have this same TE,
目前其他的哺乳动物没有这种转座元素
but the researchers did find analogous sections of DNA
但研究人员在包括人类在内的
in seven other mammal species, including humans.
其他7种哺乳动物中发现了类似的DNA片段
And all of them seem to switch on before embryo implantation.
在胚胎植入前 这些片段似乎就激活了
This is the first time that scientists have reported
这是科学家首次宣布
a TE being critical to mammalian development.
转座元素对哺乳动物的成长至关重要
But if mice can’t survive without it, that suggests they need the TE
但是如果没有转座元素 老鼠就没法存活 这表明它们需要
to help switch on Cdk2ap1, which in turn is required for implantation.
有助于激活Cdk2ap1的TE 转而来让胚胎着床
And that is pretty compelling!
这是相当有说服力的
Plus, it has implications for human fertility.
此外 它对人类的生育也有影响
A huge number of miscarriages in humans don’t have a clear genetic reason.
大量的人类流产还没法用基因解释
It’s possible that the answer may actually lie in a transposon,
原因可能就出在转座子上
just like with the knockout mice.
就像那些改造基因敲除的老鼠
So it turns out that DNA that was once trash, might actually be treasure.
所以结果是 曾经是垃圾的DNA 可能真的是宝藏
Thanks for watching this episode of SciShow, which was brought to you today
感谢观看本期《科学秀》
and for all of 2021 by the generous support of our patrons.
本期和2021年所有的《科学秀》都靠大家慷慨的赞助
If you’d like to get involved next year,
如果您明年有意要参与赞助的话
you can get started at patreon.com/scishow.
请登录网址patreon.com/scishow.
We have some great perks for you there, and also, we will be eternally grateful.
我们将感谢不尽 并会给您很好的福利
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视频概述

因新冠而错过的三件事:一是造成恐龙灭绝的陨石从哪里来,二是已知的最早古人类艺术新发现,三是DNA中转座元素的新功能。

听录译者

收集自网络

翻译译者

毛毛虫

审核员

审核员SRY

视频来源

https://www.youtube.com/watch?v=3M7ilo031aE

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