Why are scientists obsessed with the Black Sea? - Helen Farr and Jon Adams

460,768 views ・ 2021-10-21

TED-Ed


Please double-click on the English subtitles below to play the video.

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It's midnight on September 16th, 2017,
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60 kilometers off the Bulgarian coast
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and 2 kilometers beneath the Black Sea’s surface.
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A remotely operated vehicle surveys the seabed,
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transmitting video to researchers above as it goes.
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Suddenly, it discerns another ghostly vessel in the gloom.
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But this is a relic from another age.
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It's an undoubtedly ancient shipwreck,
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but its mast, rowing benches, and some of its upper deck remain eerily intact.
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It might be an ancient Roman ship, but its appearance doesn’t quite match.
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Notably, its splayed rudder blade more closely resembles
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those depicted on an even older Greek vase.
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To get a definitive answer, the research team takes three samples from the wreck
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and radiocarbon dating confirms its ancient origins.
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The ship is dated to between 350 and 410 BCE.
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It is, in fact, the oldest intact shipwreck ever found.
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This ancient Greek vessel traversed the Black Sea’s coasts
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during the time of Aristotle and has since rested in its depths,
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unseen and undisturbed, for almost 2,500 years.
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This was just one of 65 shipwrecks a research team discovered
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at the bottom of the Black Sea between 2015 and 2017.
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Others date from the Roman, Byzantine, and Ottoman empires.
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And despite the centuries, they’ve all survived in remarkable condition.
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So, why does the Black Sea contain so many well-preserved shipwrecks?
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In prehistoric times,
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the land surrounding the Black Sea hosted early human settlements.
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Eventually, it became a hub for trade, battle, and empire-building
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because of its strategic position
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between eastern and western Eurasian civilizations.
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For thousands of years, it was traversed by merchants, pirates, and warriors.
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And with sustained seafaring activity came inevitable losses.
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But unlike other bodies of water in the region,
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the Black Sea is a particularly deep, semi-enclosed basin.
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Seasonal changes usually cause the layers within a contained body of water
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to mix together, oxygenating the water.
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But because the Black Sea is fed with fresh water from European rivers,
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and saltwater from the Mediterranean Sea, it contains two distinct layers.
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The denser saltwater flows beneath the freshwater,
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where it remains permanently,
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making the Black Sea the world’s largest meromictic— or un-mixing— basin.
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Oxygen doesn’t reach its lower, saltier zone,
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which creates the ideal environment for preservation,
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and is why the Black Sea has been called “the world’s biggest pickle jar.”
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In other bodies of water, marine organisms decompose materials over time.
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Had the ancient Greek ship sunk in the Mediterranean, for example,
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there would likely be no organic material left today.
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But in the depths of the Black Sea,
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only anaerobic bacteria— those that don’t require oxygen— can survive.
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This is why ancient ships can still be found carrying their original cargo,
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with carvings in their wood, and their rigging still assembled.
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Among the recent findings was a medieval Italian merchant ship,
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likely from around the time Italy had a virtual monopoly over Black Sea trade.
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Venetian traveler Marco Polo would’ve probably been familiar
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with this kind of ship.
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Although vessels like this one helped to modernize Europe,
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contemporary scholars had never before seen such a complete example.
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And it was largely intact—
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a ship’s boat still lying on its deck,
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even though some seven centuries had passed.
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Many of the 65 ships that were recently uncovered
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have retained their original forms.
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But while there are far fewer degradative forces at play in the Black Sea’s depths,
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anaerobic bacteria do gradually weaken organic materials.
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When researchers lifted a plank from the ancient Greek wreck for dating,
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it broke under its own weight.
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While the ships are exceptionally well-preserved, they're also fragile.
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This makes it impossible to bring them to the surface intact.
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Scientists may carefully remove and study select objects from the wreckages.
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But the sunken ships will remain protected where they are,
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perhaps among thousands of others—
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deep beneath us, suspended in time, at the bottom of the Black Sea.
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