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リスニング練習
リスニング練習
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This HAS to be the weirdest mammal on Earth… right?!
This HAS to be the weirdest mammal on Earth… right?!
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0:00
- See if you can guess what animal I'm talking about.
0:02
It lives underground in a meticulously organized society
0:06
in a colony of workers with only one queen.
0:08
Oh, and it's a warm-blooded, somewhat hairy mammal.
0:13
I'm talking about the naked mole-rat.
0:15
You know, Rufus from "Kim Possible"?
0:18
And if you though I was talking about an insect,
0:19
that makes sense because I think naked mole-rats
0:22
are basically mammals that are running on insect software.
0:25
That's because they are eusocial
0:27
like bees, wasps, ants, and termites.
0:30
Each group has a single breeding queen,
0:33
and she breeds with one to three males from that group
0:35
and makes thousands of babies over her lifetime.
0:38
And no other female from the colony reproduces,
0:41
which gives them one of the highest levels of inbreeding
0:44
of any mammal.
0:45
But they've been inbreeding for so long
0:46
that they've basically bred out all the bad gene variants
0:49
that they once had.
0:50
Now, instead, naked mole-rat females,
0:52
they end up as dedicated workers with special tasks.
0:56
They're split up into teams digging underground tunnels,
0:59
defending the nest from predators, fetching food,
1:02
and raising the queen's babies.
1:04
In social structures like this, the success of the colony
1:07
and all the genes that they share,
1:09
that matters more than the success of the individual.
1:12
Unlike bees or ants or termites, though,
1:14
naked mole-rats can change their job over time.
1:17
They're not genetically encoded to do just one thing.
1:20
I mean, got to have flexibility in a job market like this.
1:23
And any female worker naked mole-rat, biologically,
1:26
could become a queen
1:28
and still can reproduce if she leaves the colony.
1:32
So unlike insects, naked mole-rat social structure
1:34
is mostly about behavior and interactions
1:37
rather than permanent genetic differences.
1:39
That means that queens are made, not born.
1:43
And when the old queen dies,
1:44
there's this violent power struggle called a mole war.
1:47
The female that wins, she asserts her dominance
1:49
and becomes the new queen.
1:51
And once she takes power,
1:52
she changes physically
1:54
and suppresses the fertility
1:56
of all the other colony members.
1:57
And some really cool new research has figured out
1:59
how naked mole-rat queens use biology
2:02
to keep the other gals in check while she's in charge.
2:05
They do it with a potent-smelling chemical, a pheromone,
2:08
that prevents other females in the colony from reproducing
2:11
by messing with their hormones.
2:13
Scientists found it by looking
2:14
in the mole-rat's vaginal secretions.
2:17
And as if all this wasn't weird enough,
2:19
that same chemical is often used in plastic
2:21
and face creams that we humans use.
2:24
Thank you, Your Majesty.
2:27
Follow me for more cool science videos.
