Clues to prehistoric times, found in blind cavefish
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0:01 - 0:03Ichthyology,
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0:03 - 0:04the study of fishes.
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0:04 - 0:07It looks like a big, boring word,
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0:07 - 0:09but it's actually quite exciting,
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0:09 - 0:12because ichthyology is the only "ology"
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0:12 - 0:14with "YOLO" in it.
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0:14 - 0:15(Laughter)
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0:15 - 0:17Now, to the cool kids in the audience,
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0:17 - 0:21you already know, YOLO stands for
"you only live once," -
0:21 - 0:23and because I only have one life,
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0:23 - 0:26I'm going to spend it doing
what I always dreamt of doing: -
0:26 - 0:29seeing the hidden wonders of the world
and discovering new species. -
0:29 - 0:31And that's what I get to do.
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0:31 - 0:35Now, in recent years, I really focused
on caves for finding new species. -
0:35 - 0:39And it turns out, there's lots of new
cavefish species out there. -
0:39 - 0:40You just have to know where to look,
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0:40 - 0:43and to maybe be a little thin.
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0:43 - 0:44(Laughter)
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0:44 - 0:48Now, cavefishes can tell me
a lot about biology and geology. -
0:48 - 0:52They can tell me how the landmasses
around them have changed and moved -
0:52 - 0:54by being stuck in these little holes,
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0:54 - 0:58and they can tell me about
the evolution of sight, by being blind. -
0:59 - 1:02Now, fish have eyes
that are essentially the same as ours. -
1:02 - 1:06All vertebrates do, and each time
a fish species starts to adapt -
1:06 - 1:09to this dark, cold, cave environment,
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1:09 - 1:13over many, many generations,
they lose their eyes and their eyesight -
1:13 - 1:16until the end up like an eyeless
cavefish like this one here. -
1:16 - 1:20Now, each cavefish species
has evolved in a slightly different way, -
1:20 - 1:24and each one has a unique geological
and biological story to tell us, -
1:24 - 1:27and that's why it's so exciting
when we find a new species. -
1:27 - 1:31So this is a new species
we described, from southern Indiana. -
1:31 - 1:35We named it Amblyopsis hoosieri,
the Hoosier cavefish. -
1:35 - 1:36(Laughter)
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1:36 - 1:39Its closest relatives
are cavefishes in Kentucky, -
1:39 - 1:41in the Mammoth Cave system.
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1:41 - 1:44And they start to diverge
when the Ohio River split them -
1:44 - 1:45a few million years ago.
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1:45 - 1:48And in that time they developed
these subtle differences -
1:48 - 1:51in the genetic architecture
behind their blindness. -
1:51 - 1:55There's this gene called rhodopsin
that's super-critical for sight. -
1:55 - 1:57We have it, and these species have it too,
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1:57 - 2:00except one species has lost
all function in that gene, -
2:00 - 2:02and the other one maintains it.
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2:02 - 2:06So this sets up this beautiful
natural experiment -
2:06 - 2:09where we can look at the genes
behind our vision, -
2:09 - 2:12and at the very roots of how we can see.
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2:13 - 2:15But the genes in these cavefishes
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2:15 - 2:18can also tell us
about deep geological time, -
2:18 - 2:20maybe no more so
than in this species here. -
2:20 - 2:23This is a new species
we described from Madagascar -
2:23 - 2:26that we named Typhleotris mararybe.
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2:26 - 2:30That means "big sickness" in Malagasy,
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2:30 - 2:32for how sick we got trying
to collect this species. -
2:33 - 2:34Now, believe it or not,
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2:34 - 2:37swimming around sinkholes
full of dead things -
2:37 - 2:39and cave full of bat poop
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2:39 - 2:42isn't the smartest thing you could
be doing with your life, -
2:42 - 2:43but YOLO.
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2:43 - 2:47(Laughter)
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2:47 - 2:51Now, I love this species despite the fact
that it tried to kill us, -
2:51 - 2:54and that's because
this species in Madagascar, -
2:54 - 2:57its closest relatives
are 6,000 kilometers away, -
2:57 - 2:58cavefishes in Australia.
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2:59 - 3:02Now, there's no way a three-inch-long
freshwater cavefish -
3:02 - 3:04can swim across the Indian Ocean,
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3:04 - 3:07so what we found when we compared
the DNA of these species -
3:07 - 3:11is that they've been separated
for more than 100 million years, -
3:11 - 3:15or about the time that the southern
continents were last together. -
3:16 - 3:18So in fact, these species
didn't move at all. -
3:18 - 3:20It's the continents that moved them.
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3:20 - 3:22And so they give us, through their DNA,
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3:22 - 3:24this precise model and measure
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3:24 - 3:28of how to date and time
these ancient geological events. -
3:29 - 3:31Now, this species here is so new
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3:31 - 3:34I'm not even allowed
to tell you its name yet, -
3:34 - 3:36but I can tell you
it's a new species from Mexico, -
3:37 - 3:38and it's probably already extinct.
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3:39 - 3:42It's probably extinct because
the only known cave system it's from -
3:42 - 3:45was destroyed when a dam was built nearby.
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3:45 - 3:47Unfortunately for cavefishes,
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3:47 - 3:48their groundwater habitat
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3:48 - 3:50is also our main source of drinking water.
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3:51 - 3:56Now, we actually don't know
this species' closest relative, yet. -
3:56 - 3:58It doesn't appear to be
anything else in Mexico, -
3:58 - 4:00so maybe it's something in Cuba,
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4:00 - 4:02or Florida, or India.
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4:03 - 4:07But whatever it is, it might tell us
something new about the geology -
4:07 - 4:11of the Caribbean, or the biology
of how to better diagnose -
4:11 - 4:13certain types of blindness.
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4:13 - 4:16But I hope we discover this species
before it goes extinct too. -
4:17 - 4:19And I'm going to spend my one life
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4:19 - 4:22as an ichthyologist
trying to discover and save -
4:22 - 4:25these humble little blind cavefishes
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4:25 - 4:28that can tell us so much
about the geology of the planet -
4:28 - 4:30and the biology of how we see.
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4:31 - 4:32Thank you.
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4:32 - 4:36(Applause)
- Title:
- Clues to prehistoric times, found in blind cavefish
- Speaker:
- Prosanta Chakrabarty
- Description:
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TED Fellow Prosanta Chakrabarty explores hidden parts of the world in search of new species of cave-dwelling fish. These subterranean creatures have developed fascinating adaptations, and they provide biological insights into blindness as well as geological clues about how the continents broke apart million of years ago. Contemplate deep time in this short talk.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 04:49
Brian Greene edited English subtitles for Clues to prehistoric times, found in blind cavefish | ||
Brian Greene edited English subtitles for Clues to prehistoric times, found in blind cavefish | ||
Brian Greene edited English subtitles for Clues to prehistoric times, found in blind cavefish | ||
Brian Greene approved English subtitles for Clues to prehistoric times, found in blind cavefish | ||
Brian Greene edited English subtitles for Clues to prehistoric times, found in blind cavefish | ||
Krystian Aparta accepted English subtitles for Clues to prehistoric times, found in blind cavefish | ||
Krystian Aparta edited English subtitles for Clues to prehistoric times, found in blind cavefish | ||
Krystian Aparta edited English subtitles for Clues to prehistoric times, found in blind cavefish |