【Native Speaker每日综合训练—35系列】【35-18】科技_Extinction

zxppx

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大家好!胖胖翔来了! 今天的主题是extinction, 希望大家能够从各种角度来了解这一main topic. Stay with us, enjoy~

Part I：Speaker

【Rephrase1】
Article 1
Biggest Mass Extinction Was Fastest, Too
It took just 60,000 years for the End Permian extinction to wipe out 96 percent of aquatic species and 70 percent of land species some 252 million years ago. Cynthia Graber reports


It was the largest of the five major mass extinctions in Earth’s history—well before the dinosaur-killer 66 million years ago. What’s called the End Permian extinction, 252 million years ago, wiped out 96 percent of aquatic species and 70 percent of species on land. Scientists have been trying to gauge the time frame of the extinction, in the hopes of determining its causes.

Now researchers say it’s the fastest mass extinction known.

Using new tools and models—including a fresh analysis of rock formations in China—the researchers determined that the extinction took only about 60,000 years. That’s incredibly quick by geological standards, and is more than 10 times faster than previous estimates.

The report is in the Proceedings of the National Academy of Sciences. [Seth D. Burgess, Samuel Bowring and Shu-zhong Shen, High-precision timeline for Earth’s most severe extinction]

Study author Samuel Bowring from M.I.T. says they can’t yet compare the speed of the previous extinction to the extinction rates caused by human activities today. But, he says, their research is starting to help reveal how past environmental changes that influenced extinctions—such as levels of carbon dioxide in the atmosphere—compare to the changes in those levels seen today. In the midst of what many call the sixth extinction.

—Cynthia Graber


Source:
http://www.scientificamerican.com/podcast/episode/biggest-mass-extinction-was-fastest-too1/

zxppx

Part II：Speed

【Time 2】
Article 2
On Earth Day, how we play a role in extinction

There are more than 40,000 endangered species in the world — plants, animals, mollusks, reptiles, etc. — according to the International Union for Conservation of Nature and Natural Resources’s Red List.

How much of that is due to us?

“The majority of species listed on the Red List are threatened or endangered due to human activities, such as loss of habitat, direct killing, climate change, etc.,” said Matt Lewis of the World Wildlife Fund.

However, “some species are naturally found in very small numbers or in very specific or isolated habitats, which puts them at risk of extinction naturally. Think of examples such as certain cave species that have evolved very specific ecological niches restricted to only one particular habitat. A natural disaster could wipe out that species through no fault of human disturbance at all.”

But sometimes humans can have positive impact.

“The Southern White Rhinoceros is one of the most compelling species recovery stories of all time,” Lewis said. “From less than 100 at the turn of the 20th century to over 20,000 today.”


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Source:
http://www.pbs.org/newshour/rundown/earth-day-play-role-extinction/


【Time 3】
Article 3
Will you survive Extinction Week?

What is extinction? For a species there is no greater failure. It’s a dead end for millennia of genetic adaptation and refinement. Extinction is the dustbin collecting the scratch paper of your discarded attempt to crack the genetic code. But extinction can also be a beginning.

This week, to mark the 44th observance of Earth Day, we invite you to join us in our pursuit to better understand extinction. We’ll explore the traditional idea of extinction you learned about in grade school science, and we want to understand other sorts of extinction, as well. What happens when ideas, technology or even ways of life go extinct?

Welcome to Extinction Week at the PBS NewsHour.

To get started we asked, where does extinction happen? The traditional idea of extinction is global: the end of the dinosaurs, the biologically doomed dodo, the much-discussed mass extinction events. But scientists are beginning to understand how smaller-scale extinctions shape our world as well. In the exclusion zone around Chernobyl, researchers have found that fallen leaves, trees and plants lie on the ground for months without rotting. The local populations of microbes, wiped out by intense radiation, have stopped doing their part to break down organic matter. So the detritus remains.

But extinction can be even more local, like when it happens inside your own body. On Science Wednesday, PBS NewsHour reporter Producer Rebecca Jacobson talks to Dr. Martin J. Blaser about his new book, “Missing Microbes.” Blaser reveals what happens when populations of beneficial human gut bacteria are wiped out. We acquire this bacteria as babies crawling in the dirt and from the contact and kisses from our family members. But city-dwelling people, living squeaky-clean antibiotic lives, have lost a third of their internal microbial diversity compared to those who live in more rural settings. Perhaps it’s time we all got a little more dirty.

Today we find out what happens when a coin becomes obsolete, as the Canadian mint collects and recycles more than 30 billion pennies that are being phased out of circulation. Later this week, we’ll meet a group living together on a Virginia commune, working to keep the values of the 1960s counterculture alive.

And we’d like you to help us find things in your world that are going extinct. Share a photo of the vacant burger joint that used to bring life to your neighborhood’s corner, or the empty shopping mall collecting dust down the street. We’re collecting them on Instagram and Facebook under the hashtag #extinctionweek.

And that brings us to the end — but not the real end. Is extinction really final anymore? On Earth Day, we’ll take a look at the controversies surrounding efforts at an emerging science called de-extinction with KQED’s Quest. It’s a mixture of conservation and genetic science focused on bringing back species that recently went extinct, like the passenger pigeon or the woolly mammoth. Proponents say it’s a way to save species we’re losing everyday. Critics worry it’s a flash in the petri dish — a distraction from the critical field science that can save these animals before they’re lost.


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Source:
http://www.pbs.org/newshour/updates/welcome-extinction-week/


【Time 4】
Article 4
Archaeageddon: how gas-belching microbes could have caused mass extinction
Study suggests gene transfer led to sudden release of methane 252 million years ago, killing most life on Earth.

Methane-belching microbes may have been behind the 'Great Dying', a mass-extinction event that wiped out some 90% of all species on Earth about 252 million years ago. Researchers say that the organisms acquired the ability to consume previously untapped food sources and went into overdrive, causing catastrophic disruption to the climate.

Microbes have had outsized effects on the planet's geology and on life, through the chemicals they consume and release. One example is the creation of the oxygen-rich environments that made the evolution of complex animals possible, or 'great oxygenation event', says theoretical geophysicist Daniel Rothman of the Massachusetts Institute of Technology (MIT) in Cambridge. But their effects can be catastrophic, too, he says.

Rothman and his colleagues looked into the causes of the Great Dying, which took place at the end of the Permian period that lasted from 300 million to 252 million years ago. Geological evidence shows that the event was accompanied by lethally high global warming and ocean acidification. The causes have long been debated, but one leading proposal points to Siberian volcanoes, which are known to have been hugely active at the time.

The paper by Rothman and his team, published this week in Proceedings of the National Academy of Sciences1, paints a fresh picture of how the extinction occurred. Leading up to it, large quantities of organic matter accumulated in ocean sediments. It was “a pile of food sitting there”, says study co-author Gregory Fournier, an evolutionary biologist at MIT, but nothing was in a position to eat it.

That soon changed. The oceans were also home to single-celled microbes known as archaea. Some, known as Methanosarcina, consume carbon compounds and release methane. But the microbes did not have a way to process acetate, one of the key compounds that made up the sediment reserves. That is, until they captured two acetate-processing genes from a bacterium. By comparing the genomes of 50 different living organisms, Fournier dated that gene transfer to 250 million years ago, right around the time of the mass extinction.


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【Time 5】

Pointing the finger
Fournier says that the evolutionary event could have led to a prodigious microbial bloom — and consequent dump of methane, a powerful greenhouse gas, into the atmosphere — because it enabled Methanosarcina to feed on the organic sediment. Moreover, Rothman thinks that he has identified the bloom’s signature in the carbon-isotopic record of the ancient sediments. Using a mathematical approach, he revealed that the concentration of some gases — possibly including methane — were increasing “exponentially or possibly super-exponentially” during the time of the extinction. Microbial activity, and not volcanism or other potential causes, is the best explanation for that kind of growth, he says.

But the Siberian volcanoes could still be part of the story, says Rothman. They were probably responsible for a sharp increase in nickel deposits that the authors found in ocean sediments from the time. In known methane-spewing microbes, the metal is a crucial component of enzymes involved in the reactions that produce the gas. The availability of nickel is in fact a limiting factor to these organisms' growth, so nickel from the volcanoes could have caused a runaway effect in Methanosarcina, says Rothman, and eventually death for other species.

Even if methane was behind the Great Dying, it is still not clear what ultimately led to the demise of many species. The increased methane could have killed life on land by causing a toxic release of hydrogen sulphide; in the oceans, animals could have suffered from oxygen depletion, and acidification would have affected creatures’ ability to grow shells.

Some scientists are not so quick to relegate the volcanoes to a supporting role, however. What the researchers have found is part of the connection between the volcanoes and the die-out, says palaeobiologist Douglas Erwin of the Smithsonian National Museum of Natural History in Washington DC. But he warns that the evidence is “hardly conclusive”.

The great oxygenation event shows that it is not that far-fetched to think that a single microbe species could have changed Earth so drastically, says Rothman. “It could happen again, and it may very well have happened at other times in the past.”


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Source:
http://www.nature.com/news/archaeageddon-how-gas-belching-microbes-could-have-caused-mass-extinction-1.14958


【Time 6】
Article 5
The Sixth Extinction


Almost nothing in nature is so rare as a mass extinction. On only five occasions in Earth’s long history has a large fraction of the planet’s biodiversity disappeared in a geological instant. But, journalist Kolbert reminds us in her new book, we are well on our way to making it six.

A lesser writer tackling this subject might offer up a dreary list of dead and dying species; Kolbert instead tells a scientific thriller. The tale begins in 1739, when strange bones turned up near the Ohio River. Stumped, the French scientist Georges Cuvier declared they must belong to a mammal that no longer exists, which he called the mastodon. As evidence for such archaic forms piled up, Cuvier went further, proposing that Earth’s history is full of lost species, and sometimes they wink out in large numbers.

Not until the last few decades did paleontologists fully accept this “catastrophism.” Most scientists now believe a meteor impact did in the dinosaurs, as well as the ammonites, extinct mollusks to which Kolbert devotes a loving chapter. That meteor had nothing on the earlier Permian extinction, though, which nearly wiped out multicellular life.

Humans are the new catastrophe. Large mammals are now mostly gone or headed that way, and we are pushing out other biota through habitat destruction and species introductions, Kolbert writes. Ecologists are feverishly studying these phenomena; Kolbert follows them to fragmented tropical rainforests in Panama and Peru, caves of bats stricken with white-nose syndrome in New York and acidifying coral islands on Australia’s Great Barrier Reef. These modern eco-disasters are depressingly familiar, but united by Kolbert’s masterful reporting, they gain a new urgency.

The scientists Kolbert meets also offer a glimmer of hope. We are, if perhaps a singularly destructive species, also unique in systematically gathering and preserving knowledge about our world. The big question, which Kolbert leaves open, is whether we can use this knowledge to avoid dooming much of the rest of life on Earth — and with it, possibly ourselves.


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Source:
https://www.sciencenews.org/article/sixth-extinction

zxppx

Part III： Obstacle

【Paraphase7】
Article 6
Can we save our body’s ecosystem from extinction?

The sheer amount of bacteria in the human body weighs three to four pounds combined, as much as the human brain. Microbial species live on the surface of our skin, in our stomachs and in our noses, outnumbering our cells 10 to 1. Our bodies are host to some 100 trillion bacteria – this is known as the human microbiome. And while the human genome has 23,000 unique genes, the human microbiome has 2 million.

Some bacteria are indisputably bad. But others boost our immunity, protect us from infection and produce the enzymes we need to digest our food. Without these bacteria, we wouldn’t survive, says Dr. Martin Blaser, author of the new book “Missing Microbes.”

“They are kind of a part of us,” Blaser said. “And my fear is that some of them are going extinct.”

Humans in the U.S. have lost a third of their microbial diversity, mostly on their skin and in their stomachs and digestive tracts, said Maria Gloria Dominguez-Bello, associate professor of medicine at NYU.

The problem is due in part to the overuse of antibiotics, C-sections and modern sanitation, Blaser says. And he believes that microbe extinction may be at the root of modern plagues like asthma, allergies, diabetes, obesity and even some forms of cancer.

Scientists are just starting to catalogue the human microbiome, said Lita Proctor, director of the National Institute of Health’s Human Microbiome Project. Understanding how these microorganisms interact inside our bodies is shifting the way medicine views the bacteria, she said.

“The human body isn’t just what you see in the mirror,” she said. “It’s an ecosystem, just like a forest, just like the ocean, where microbes of many different species are interacting to support the whole.”

Enter Helicobacter pylori, a spiral-shaped bacteria with a long tail that’s been called the “poster child for microbial extinction.” It was originally known for causing ulcers at a time when doctors believed no bacteria could survive the stomach’s acidic environment. In fact, Dr. Barry Marshall, who discovered the bacteria, drank a vial of the stuff, and within weeks, developed stomach pains and gastritis, precursors to the stomach ulcer. (Marshall and colleague Robin Warren earned the Nobel Prize in 2005 for their research.)

At first, Blaser too believed H. pylori was bad. But his research showed just the opposite. This microbe, he found, was interacting with the immune cells that line our stomach. And losing it appeared linked to several immune and metabolic disorders: asthma, allergies, celiac disease, even acid reflux disease.

H. pylori, like much of our microbiome, is acquired early in life. Contrary to popular belief, babies are not born sterile, Dominguez-Bello said. They inherit much of the bacteria they need from their mother’s vagina during birth. A pregnant woman’s vaginal bacteria changes and diversifies as she prepares for birth, she explained, so children born via Cesarean section may be missing out on an important inoculation.

“For me, the vaginal microbiome is kind of the seeding place of the human microbiome, and there is a lot of maternal inheritance,” she said. “It’s very intriguing. I think the vagina could have most of the human microbiota there. So that’s when the baby gets a single inoculum of the different species that will be selected for in different body sites.”

Babies are magnets for bacteria, she explained, and they continue to pick up other microbes after birth. Each hug and kiss from mom and dad exposes them to more of the bacteria they’ll need by age 3, when they should have the majority of their microbiome in place. And by age 10, if they haven’t acquired H. pylori, they likely will never have it, Blaser said.

In the early 20th century, most Americans had H. pylori in their stomachs. Fast forward to present day, and fewer than 6% of American children born after 1995 have it. These trends are the same in Australia, Germany, the Netherlands and Scandinavia.

“One day it occurred to me that this is an ancestral organism that’s disappeared. But ancestral organisms aren’t supposed to disappear,” Blaser said. “If one guy is disappearing, maybe some others are disappearing.”

One of the key changes over the last century has been antibiotics, he said. Often life-saving drugs, they are also over prescribed for minor and non-bacterial infections, many scientists believe. And they knock out the good bacteria as well as the bad. Overexposure to antibiotics has led to the rise of drug-resistant bacteria like MRSA, making our drugs less effective against the bad bacteria.

Exposure to antibiotics early in life also increases a child’s risk of obesity. In fact, farmers use low doses of antibiotics to fatten up their livestock.

Blaser advocates saving and studying our human microbes. Dominguez-Bello has been traveling to South America and partnering with other researchers to collect skin, mouth and fecal samples from people in isolated communities. So far they have samples from Amerindians in Venezuela, the Quecha people in Bolivia, the Achar in Peru, rural and urban dwellers in Brazil and Hadza hunter-gatherer tribes in Tanzania.

“If you look at the feces or skin you can tell,” she said. “You can tell if this is from U.S. or isolated peoples…U.S. and westernized people are really outliers. We are always left with the doubt: is it really human? What is it doing there? Have we lost that function?”

Looking further back in time, the microbiomes of people in isolated communities are similar to those of our pre-20th century ancestors, said Cecil M. Lewis, associate professor of molecular anthropology at the University of Oklahoma. By studying bacteria from coprolites (that’s a fancy word for fossilized poop), he found that our cosmopolitan guts have lost bacteria like spirochaetes and prevotella, which may have helped our ancestors digest carbohydrate-rich diets and tough fibrous plants. These bacteria are now rare in modern city-dwelling stomachs.

The data is eye-opening, Proctor said.

“It’s shocking when you look at numbers how much total diversity has been lost. Is it gone from the planet, or can we recover them?” she asked. “We’re trying to come up with reference point — what’s the least disturbed microbiome?”

Dominguez-Bello hopes to culture the bacteria she is gathering around the world so it can be studied and saved from extinction. But travel and sequencing the DNA of each bacterium is expensive, and currently Dominguez-Bello has support from private foundations and is seeking federal funding. She collaborates with other researchers and rides along with government and NGOs in helicopters to reach villages on mountaintops and deep in the rainforest.

This field of microbiology is still in its infancy, and we’re still trying to understand our gut’s diversity, both past and present, Lewis said.

“I don’t think these bugs are extinct in urban populations,” he said. “I think we’ve repressed them. Certainly, it is possible for humans to drive some bacteria species to extinction, but given how easily most bacteria species adapt…it’s not easy. For example, if you look deep enough in urban populations, you’ll still find those spirochaetes …they are just much more rare.”

But Carl Zimmer, science writer for The New York Times and author of the book, A Planet of Viruses said that it is possible for species of microbes to vanish completely.

“From what we know about the ecology of bacteria, it certainly is possible that we could wipe them out,” he said. “Antibiotics are an incredibly powerful weapon against bacteria. You can see them knocking out species from individual people, and some species just don’t come back. If you keep repeating that, it’s harder for bacteria to keep going…if we are attacking them in the only place they can call home, it’s not like they can go anywhere else.”

Blaser thinks it’s important to preserve that environment. This isn’t to say that antibiotics or sanitation or C-sections are bad, but they do have consequences, he said. For example, he said, doctors should stop over-prescribing antibiotics, especially to young children. Researchers should work on new antibiotics that can target specific infections, minimizing the good bacteria casualties, and potentially developing effective probiotics — these are beneficial microbes introduced into the body. And go easy on the hand-sanitizers and anti-bacterial soaps, he said.

“Not caring about your microbiome is like not caring about your liver or your spleen,” Zimmer said. “They’re an important part of your body. You need to be concerned.”

Oh, and that probiotic yogurt you’ve seen advertised? It hasn’t been studied or tested, Blaser added, so don’t trust that it will repopulate your gut.


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Source:
http://www.pbs.org/newshour/updates/theres-extinction-happening-stomach/

静月飘风

抢前排！
Time2 0:45
Human's impact on animal extinction: The majority of species on the Red List are endangered due to human activities. However, some species are naturally at risk of extinction. Sometimes human can have positive impact.

Time3 3:12
Extinction is not just the end, perhaps the beginning. On Earth Day, we invite you to discuss extinction.
- Where does extinction happen? global, smaller-scale, even local

Time4 2:13
Scientists from MIT find that the Great Dying is perhaps caused by methane-belching microbes.

Time5 2:49
Micobial bloom were behind the Great Dying

Time6 1:46
The sixth mass extinction is caused by human activities.

Obstacle 6:32
Many bacteria are benefit to our health. They contribute to our immune system. But now, compared with our 20th ancestors and people who live in isolated area, urban people have lost many useful microbes.

wangweiyi5332

占~~~~~~~~~~~~~~~~~~~~~~~
Timer2 1:02
Most species of animals have extincted due to human activities,such as habitat destruction, direct killing and climate change, but few specie were putted at risk of extinction by nature.
Timer3 3:25
extinction is an end for millenna of genetic adaption and refinement. But extinction may mean a new beginning . the whole extinct area ,the microorganism stop eroding the organic . Now science technology can bring back some species that went out extinction .
Timer4 2:30
Microbes may the big reason behing the Great Dying.Microbes have had outsized effects on the planet's geology and on life, through the chemicals they consume and release.  the debate considered that at that time the ocean had nothing for animals to eat. but it changed .Microbe consume carbon and release methane changing the ocean environment a lot.
Timer5 2:35
Microbe release methane which lead to the Great dying ,but some researchers proposed that nicken is important to the chemical reaction which need the n as enzyme.
Timer6 2:35
human activities is going to make the six main extinction.
Timer7 8:19

疏离无罪

占～～～～～～

Speaker:The largest of the five major mass extinctions in Earth’s history happened 66 million years ago.The enviornment change is the main cause.It's hard to campate it to the extinction rates caused by human.

00:40
There are more than 4000 endangered species in the world.And most of the listed species are caused by human.But human can also have positive impact.

02:51
Extinction can be even more local.The microbes in our body are reducing now.Extinction is not real end.A mixture of conservation and genetic science can be used to save these animals.

01:40
Methane-belching microbes may be the main cause of the Great Dying.This microbes consume carbon compounds and release methane and lead to catastrophic disruption to the climate.

01:44
The evolutionary event led to a prodigious microbial bloom and the microbe activity release a lot methane that change the clmate.Nickel from the volcanoes also caused a runaway effect in this process.

01:32
Humans are the new catastrophe that lead to the sixth mass extinction.

08:10
Main Idea: We are losing our microbe diversity in our body
Our bodies are host to some 100 trillion bacteria,both good and bad ones.Most of them plays important roles in our body.But now some of them are becoming extinction.People in the US have lost one third of their bacteria diversity.The mircobe extinction may lead to morden plagues.Our body is just like a ecosystem.All kinds of microbes are essential.Raise an example of good bacteria in our stomach called H.pylori.
Some of the bacteria comes from our mother when we in the vigina.And baby are magnets for bacteria.They can get most of the necessary bacteira by age 3.But if they can not get the microbes by age 10,they won't get them any more.
The key change may be the antibiotic.It can knock out all good and bad bacteria in our body.And exposure to antibiotic early will lead to obesity.Because of antibiotic,we may lost some of the bacteria forever.Since our body is the home of the bacteria,they can go nowhere if they are knock out.

Yvonne52585

主页菌好贴心，前两天没完成作业还过来督促我一下，小分队真的好赞！大家都要加油！

Tutuba

This is my first homework.
Time 2 1:16 human impact most badly, has no impact no some, has positive impact on some
Time 3 3:28 call for other ext. example. ext not final
Time 4 3:05 mic cause ext
Time 5 2:50  food source for mic->ext of others
Time 6 3:08 Kobert wrote about ext. by human impact.

Time 7 8:20 good bac. antib/c-c kills good b.
baby acquire good b at birth by age 3 mostly complete. good b ext? should limit antib and cc

cherry6891

thanks~~~~~~ppx

Obstacle:9’12’’

We were born with thousands of various bacteria which form a ecosystem and may relate close to the diabetes,asthma,obesity

But currently over-predescribing antibiotic, C-sections operation decrease the bacteria in body

Less attack the body which is home to bacteria ,keep the ecosystem in body

Time2 1’00’’

Over 40000 endangered species in the world

Human can have positive impact on that

The example of hite rhinoceros

Time3 3’40’’

the bigger definition of extinction-dead end for millennia of genetic adaption and refinement

Small distinction sharp our worlds as well

The distinction can be more local ,for examplebacteria in body lost 1/3 the diversity of

Time4 2’40’’

In the paper by R the volcanoes may cause the Great Dying which accopanied by high global warming and ocean acidification.

Large quantities of organic matter accumulate in ocean sediment and then archae consume carbon compounds and produce acetate which compounds the sediment

Time5 3’05’’

Evolutionary event led to microbial bloom and consequent dump of methane(the increase of methane is exponentially by a math approach)

The sequence and relationship of the volcanoes, Great Dying and microbial bloom

mozhiwanjia

zxppx 发表于 2014-4-29 23:46
Part III： Obstacle
【Paraphase7】
Article 6

掌管 6        00:13:45.87        00:32:51.21
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