Shadowing Practice: What’s Ruining Our Ruins? - Learn English Speaking with Video

בחר מצב תרגול

כל מצב פותח חדר תרגול במסך מלא.

120 משפטים

אם המשפטים קצרים או ארוכים מדי, לחץ על ערוך כדי להתאים אותם.

The United Nations has designated roughly 1,000 culturally important world heritage sites around the world.

But at many of them, something has quietly been going wrong.

Paintings are flaking away, wood is rotting, even stone is slowly dissolving into powder.

If you're wondering what's so powerful that it could take down some of our oldest and most protected sites, well, this destruction isn't the product of war or natural disasters or other huge events.

It's the work of microbes.

Here's how some mini-microbes are ruining our ruins.

First up, we're going to the Maijishan Grottoes,

a series of roughly 200 caves carved into the side of a sheer sandstone mountain in the Gansu province of northwest China.

You have to be feeling brave to cross these soaring walkways that lead inside, but once you've entered Agrano,

you can find sculptures and wall paintings from as far back as the 300s.

But despite standing through 1700 years, the site is in trouble.

In 2018, experts reported that microbial plaques had started growing on the art.

As far as we know, it's not like microbes hate art or something.

They do this to make a home for themselves or to get nutrients.

In fact, while a painting might seem like a weird place for life to grow, if you're a microbe, paintings can be full of tasty bits.

There's the paint itself, which might contain things like plant oils, egg yolk, or animal glue.

But there may also be layers of organic materials like straw or other plant fibers beneath as well,

which the ancient painters would have slathered on the wall to give themselves a smooth surface to work on.

That is a balanced meal for a microbe.

As for what kind of microbes, there's a wide variety of bacteria and algae.

Both of those organisms can do art damaging things like poop out acids or form gooey biofilms that can trap water.

You can also get molds and other fungi growing on those ruins, which spread their root-like hyphae underneath the surface looking for nutrients.

All these little fellas can physically separate the layers of a painting, causing bits to flake or fall off.

They can also cause changes in color, either by degrading existing pigments or by adding their own colors into the mix.

Green algae can turn things, well, green.

Certain bacteria can do green as well, plus yellow, brown, or black.

One kind of bacteria can even create a lovely salmon pink.

But in the case of Maijishan, there were mainly white and black splotches appearing on the walls.

When scientists analyzed the splotches, they found that a common decomposing fungus was the dominant microbe in the black biofilms.

Meanwhile, Cladosporium, a super common indoor mold, and an unclassified species of fungus were dominant in white biofilms.

As for what caused the outbreak, they don't know for sure, but it probably had to do with cave critters.

The decomposing fungus is associated with arthropods, like bugs, and fungi can also grow on animal dung or after flooding.

So animals getting into these caves to shelter from heavy rains might be contributing.

In fact, previous work on the splotches also pointed fingers at excess humidity as a possible cause

and suggested it could be from more human visitors or even shifts in the weather thanks to climate change.

We know this is possible.

The Lescaux Caves in southwestern France contain wall paintings from as far back as 22,000 years ago.

But after their rediscovery in the 1940s, lots of people began visiting, and the carbon dioxide, heat, and water vapor from their breath caused microbes to grow.

The authorities eventually closed the caves to the public, and for 40-ish years tried using biocides, including antibiotics, to get rid of those microbes.

And it worked on some of the microbes.

But that opened up space for a new fungus to move in, which left a whole new set of white stains behind.

Similar things happened when people tried to disinfect the frescoes of St. Paul in Ephesus.

So biocides don't always work as well as we hope.

Another option is manual removal, like using soft brushes, a vacuum, and a little bit of elbow grease,

which they tried in the Maijishan grottos, along with biocide treatments.

Those measures seem to have worked well, even though this is probably going to be an ongoing project.

But paintings aren't the only type of heritage under pressure for microbes.

We've also had some problems with wood.

But before we go there, it's time for a quick ad.

Worth Knowing, and it's live at the Wilshire Ebel Theater in Los Angeles, California on September 16th, 2026.

This first ever Complexly In-Person event is a fundraiser to support our mission of inspiring curiosity and lowering barriers to knowledge building.

Because curiosity builds understanding, and understanding builds a better world.

You can get your ticket at somethingworthknowing.org.

See you there.

In the desert of New Mexico, you can find Chaco Canyon.

It's another UNESCO World Heritage Site, occupied by the ancestral Puebloan people for about 300 years, starting around the mid-800s.

While they were there, they built impressive great houses and other infrastructure out of stone and wood.

And so far, it's stood the test of time, but not entirely unscathed.

For example, in the mid-aughts, expert examined some of the wooden beams that made up the buildings and found a significant amount of damage.

Some was from weathering and other physical processes, but some was from microbes.

Now, wood, especially wood in harsh, dry environments like the New Mexico desert, can be pretty resistant to microbes like bacteria.

Wood is tough and durable because plant cells are surrounded by cell walls, and woody plants in particular pack them especially full of tough,

hard-to-break-down molecules like cellulose and lignin.

But wood is vulnerable to fungi because they have ways to get into and even get food from these compounds.

One of the main troublemakers is a group of fungi that includes brown rot fungi.

These little guys specialize in decaying the cellulose in plant cells, leaving the colorful lignin behind.

This turns the wood soft, but leaves the wood's brown color behind.

And that's where they got their name.

White rot fungi, meanwhile, turn wood white, since they decay everything, including lignin.

Some even specialize in lignin.

Another major kind of fungal wood decay is soft rot.

This looks really similar to brown rot.

In fact, it's so similar

that you generally need to look at samples under a microscope to tell soft rot and brown rot apart, even though the organisms behind the rot are pretty different.

And experts have found some brown rot and a lot of soft rot setting in at Chaco.

Some parts of the wood were so degraded they could be crushed into a fine powder with even slight pressure.

Part of the problem may have come from fissures in the wood, which can catch moisture and nutrient-rich particles from the environment, the perfect conditions for microbes to move in.

In this case, instead of biocides, we've been reburying parts of the site since the 1980s.

The idea is that digging them up likely exposed them to the moisture the fungi needed to thrive, so reburying them should hopefully remove that moisture and stop further growth.

As an added layer of protection, conservationists also installed things like moisture monitors alongside the buried material,

as well as waterproof fabric sheets or drains and pipes that can funnel surface water away from stuff buried further down.

Free burial is pretty low-tech, practical, and compared to trying to replace the wooden beams or other materials again and again, a good deal money-wise.

We like to imagine technology solving all our problems, but sometimes the best option for archaeologists is to leave things alone and preserve them for the future.

We can get the technology to fix it later.

Although eventually everything breaks down, whether it's paint or wood or even stone itself, as our last location shows.

In 2018, scientists took samples from a bunch of sites in Egypt, from tombs and obelisks to mosques and even the pyramids at Giza.

These sites are ancient and have withstood the test of time, but over the years, people have noted damage at some of them,

including black stains and pitting in the rocks themselves.

Scientists have found two species of a common mold, along with Cladosporium, one of the fungi found at Mygishan.

And we're not just seeing it in Egypt.

Another desert site, Megiddo, was surveyed in 2023.

This World Heritage site was swabbed from the visitor entrance to its major archeological sites.

Experts didn't report damage, but did detect acid producing microbes.

As for what a microbe would even want with stone, just like wood or paintings, it can give them a home and even food.

They might even damage the stone itself by doing things like dissolving minerals from the rocks, which unfortunately for UNESCO can be especially damaging in rocks like limestone.

Plus they can cause damage through things like those watery biofilms and root-like hyphae.

And And in some cases, they can even poop out salts, which can be destructive both chemically and physically, if it starts to build up in cracks and force them apart.

Case in point, the Egyptian group applied cladosporium fungi to some fresh stone and found it discolored and weakened.

It had even dissolved some of the stone after just two months.

100

To treat those issues, they tried a bunch of different biocides on their stone blocks and found some that worked,

101

including synthetic topical antiseptics, as well as natural options like clove oil.

102

But we don't want to go indiscriminately killing all life at these UNESCO sites, because in some cases, microbes might actually protect them.

103

At Angkor Wat in Cambodia, for example, scientists found that lichens might help protect the stone buildings there from water damage.

104

They were effectively shielding the site from the weather, and may also have been pushing out other microbes that could have damaged the site.

105

Now, lichens are actually a mix of microscopic bacteria and algae living inside a kind of fungal web, and some of them are microscopic so they might tow the line of microorganism,

106

but for the purposes of this video, we are counting them.

107

But if you're not team microbe when it comes to lichens, there are still other protective guys under the microscope.

108

Some scientists are even experimenting with the idea of purposefully applying certain harmless bacteria

109

or amoebas to different archeological sites as a preventative or even restorative treatment.

110

In plaques and other microbial communities, including ones from places like murals or ruins, there are protective microbes that may crowd out,

111

chemically suppress or directly prey upon the ones that cause damage.

112

There are even microbe-targeting viruses we might be able to use.

113

One group experimented with using sulfate-eating bacteria to remove unsightly black sulfate-rich gypsum deposits from the base of a famous marble sculpture,

114

Michelangelo's Rondonini Pieta.

115

The bacteria were mixed into a gel that could be slathered onto the sculpture.

116

A day later, scientists came back, washed it off, and found that the deposits were gone.

117

So along with all of the publications coming out that highlight microbes' destructive ways, people are experimenting with plenty of them that could help in preservation.

118

We often talk about these sites as if they're kind of frozen in time, but in fact, they're constantly changing ecosystems.

119

Microbial research helps us understand those changes so we can preserve the sites for generations to come.

120

Sometimes if you want a better view of the future, you need to get out a microscope.

הורד אפליקציה

כל מה שאתה צריך כדי לדבר בשטף

הגיית AIציון לכל משפט

תרגול IPAשלוט בכל צליל

אוצר מיליםבנה את מאגר המילים שלך

משחק אוצר מיליםלמד תוך כדי משחק

סרוק QR

Download on theApp Store Get it onGoogle Play

אותו ערוץ

Two Different Things Are Killing Sharks

מילה	הגייה	משמעות
microbe שם עצם	/ˈmaɪkɹoʊb/	חַידַק
bacterium שם עצם	/bækˈtɪəɹ.ɪəm/	חַיְדַּק \ חידק
fungus שם עצם	/ˈfʌŋ.ɡəs/	פטרייה
moisture שם עצם	/ˈmɔɪs.t͡ʃɚ/	לַחוּת
alga שם עצם	/ˈæl.ɡə/	אַצָּה
lichen שם עצם	/ˈlaɪ.kən/	חֲזָזִית
microscope שם עצם	/ˈmaɪ.kɹəˌskoʊp/	מִיקְרוֹסְקוֹפִּ
decay שם עצם	/diˈkeɪ/	דעיכה
sculpture שם עצם	/ˈskʌlpt͡ʃɚ/	פֶּסֶל
cellulose שם עצם	/ˈsɛljəloʊs/	תאית
organism שם עצם	/ˈɔɹ.ɡəˌnɪz.əm/	אוֹרְגָּנִיזְם, יְצוּר
poop שם עצם	/ˈpuːp/	קָקִי, קָקָה
mold שם עצם	/moʊld/	טַחַב, עֹבֶשׁ
destructive שם תואר	/dɪˈstɹʌktɪv/	הרסני
bury פועל	/ˈbɛɹi/	קָבַר

מילה	הגייה	משמעות
come back פועל		שָׁב
come out פועל	/ˌkʌm ˈaʊt/	יָצָא

מבנה	בסרטון
הווה מושלם (Present perfect) have/has + past participle — פעולה שקרתה בעבר ועדיין יש לה חשיבות או השפעה עכשיו	has designated · you've entered · We've also had
סביל (Passive voice) be + past participle — הדגש הוא על מה שקורה, לא על מי שעושה את הפעולה	is associated · are surrounded · could be crushed
משפטי זיקה (Relative clauses) who / which + clause — מידע נוסף על אדם או דבר	wood, which can · salts, which can

Shadowing Practice: What’s Ruining Our Ruins? - Learn English Speaking with Video

בחר מצב תרגול

הורד אפליקציה

Two Different Things Are Killing Sharks

Why Do We Sneeze?

The Science Behind The Odyssey's Greatest Challenge

Do Penguins Control the Weather?

The Most Important Picture in the History of Science

Why Can’t We Have Unicorns?

Does Aloe Really Treat a Sunburn?

What's Really Behind The Adderall Shortage?

Ticks Can Spread An Allergy To… Red Meat?

The ONE Disease That Smoking Can Help Treat

How Onions ACTUALLY Make You Cry (And How to Stop Them)

Something’s Happening to the Ozone Hole

How mass tourism is destroying cities

Why Ancient Humans Were The Most TERRIFYING Animal Alive

Biodiversity | Consider This #4

Micro-Biology: Crash Course History of Science #24

Why Study Art? | TateShots

The British Museum is full of stolen artifacts

Every Dodo You’ve Ever Seen Is Probably Wrong. These Aren’t.

Our Greatest Delusion

IELTS listening actual test Part 4: The archeological site of Trimera (answer+ transcript)

The Most Gruesome Parasites – Neglected Tropical Diseases – NTDs

The Ocean Is Deeper Than You Think. We Need Better Maps.

אוצר מילים והערות הגייה לשיעור הזה

אוצר מילים מרכזי בסרטון הזה

Phrasal verbs שתשמעו

דקדוק בסרטון הזה

הגייה ששווה לשים לב אליה

איך לתרגל עם הסרטון הזה

מהי טכניקת השאדואינג?