What is so special about the human brain? | Suzana Herculano-Houzel

781,167 views ใƒป 2013-11-26

TED


์•„๋ž˜ ์˜๋ฌธ์ž๋ง‰์„ ๋”๋ธ”ํด๋ฆญํ•˜์‹œ๋ฉด ์˜์ƒ์ด ์žฌ์ƒ๋ฉ๋‹ˆ๋‹ค.

๋ฒˆ์—ญ: Gemma Lee ๊ฒ€ํ† : Damin Park
00:12
What is so special about the human brain?
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์‚ฌ๋žŒ์˜ ๋‡Œ๋Š” ๋ฌด์—‡์ด ๊ทธ๋ฆฌ ํŠน๋ณ„ํ•œ ๊ฑธ๊นŒ์š”?
00:15
Why is it that we study other animals
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์™œ ๋‹ค๋ฅธ ๋™๋ฌผ๋“ค์ด ์šฐ๋ฆฌ๋ฅผ ์—ฐ๊ตฌํ•˜๋Š” ๋Œ€์‹ 
00:17
instead of them studying us?
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์šฐ๋ฆฌ๊ฐ€ ๊ทธ๋“ค์„ ์—ฐ๊ตฌํ•˜๋Š” ๊ฑธ๊นŒ์š”?
00:19
What does a human brain have or do
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์‚ฌ๋žŒ์˜ ๋‡Œ๋Š” ๋‹ค๋ฅธ ๋‡Œ์— ์—†๋Š”
00:21
that no other brain does?
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๊ทธ ๋ฌด์—‡์„ ๊ฐ€์ง€๊ณ  ์žˆ๊ฑฐ๋‚˜ ํ•  ์ˆ˜ ์žˆ๋Š” ๊ฑธ๊นŒ์š”?
00:23
When I became interested in these questions about 10 years ago,
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์ œ๊ฐ€ 10์—ฌ ๋…„ ์ „ ์ด ์งˆ๋ฌธ๋“ค์— ๊ด€์‹ฌ์„ ๊ฐ€์ง€๊ธฐ ์‹œ์ž‘ํ–ˆ์„ ๋•Œ
00:26
scientists thought they knew what different brains were made of.
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๊ณผํ•™์ž๋“ค์€ ๊ฐ๊ฐ ๋‹ค๋ฅธ ๋‡Œ๋“ค์ด ๋ฌด์—‡์œผ๋กœ ๋งŒ๋“ค์–ด์กŒ๋Š”์ง€ ์•ˆ๋‹ค๊ณ  ์ƒ๊ฐํ–ˆ์Šต๋‹ˆ๋‹ค.
00:28
Though it was based on very little evidence,
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๋น„๋ก ๋นˆ์•ฝํ•œ ๊ทผ๊ฑฐ์— ๋ฐ”ํƒ•์„ ๋‘์—ˆ์ง€๋งŒ
00:30
many scientists thought that all mammalian brains,
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๋งŽ์€ ๊ณผํ•™์ž๋“ค์€ ์‚ฌ๋žŒ์˜ ๋‡Œ๋ฅผ ํฌํ•จํ•œ
00:32
including the human brain,
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๋ชจ๋“  ํฌ์œ ๋ฅ˜์˜ ๋‡Œ๊ฐ€
00:34
were made in the same way,
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๊ฐ™์€ ๋ฐฉ์‹์œผ๋กœ ๋งŒ๋“ค์–ด์กŒ๋‹ค๊ณ  ์ƒ๊ฐํ–ˆ๊ณ 
00:35
with a number of neurons that was always
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๋˜ ์‹ ๊ฒฝ ์„ธํฌ์˜ ์ˆ˜๋Š”
00:37
proportional to the size of the brain.
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๋Š˜ ๋‡Œ์˜ ํฌ๊ธฐ์— ๋น„๋ก€ํ•œ๋‹ค๊ณ  ์ƒ๊ฐํ–ˆ์–ด์š”.
00:39
This means that two brains of the same size,
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ํฌ๊ธฐ๊ฐ€ ๊ฐ™์€ ๋‘ ๊ฐœ์˜ ๋‡Œ์—์„œ,
00:41
like these two, with a respectable 400 grams,
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์˜ˆ๋ฅผ ๋“ค์–ด, ๋‘ ๊ฐœ์˜ ๋‡Œ๊ฐ€ ๊ฐ๊ฐ 400๊ทธ๋žจ์ด๋ผ๋ฉด
00:45
should have similar numbers of neurons.
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๋น„์Šทํ•œ ์ˆ˜์˜ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ์–ด์•ผ ํ•œ๋‹ค๋Š” ๋œป์ž…๋‹ˆ๋‹ค.
00:47
Now, if neurons are the functional
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์ž, ๋งŒ์•ฝ ์‹ ๊ฒฝ ์„ธํฌ๊ฐ€
00:49
information processing units of the brain,
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๋‡Œ์˜ ์ •๋ณด์ฒ˜๋ฆฌ ๊ธฐ๋Šฅ ๋‹จ์œ„๋ผ๋ฉด
00:52
then the owners of these two brains
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์ด ๋‘ ๋‡Œ์˜ ์ฃผ์ธ๋“ค์€
00:54
should have similar cognitive abilities.
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๋น„์Šทํ•œ ์ธ์ง€ ๋Šฅ๋ ฅ์„ ๊ฐ€์ง€๊ณ  ์žˆ์–ด์•ผ ํ•ฉ๋‹ˆ๋‹ค.
00:56
And yet, one is a chimp,
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๊ทธ๋Ÿฌ๋‚˜ ํ•˜๋‚˜๋Š” ์นจํŒฌ์ง€์˜ ๋‡Œ์ด๊ณ 
00:59
and the other is a cow.
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๋‹ค๋ฅธ ํ•˜๋‚˜๋Š” ์†Œ์˜ ๋‡Œ์ž…๋‹ˆ๋‹ค.
01:01
Now maybe cows have a really rich
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์–ด์ฉŒ๋ฉด ์†Œ๋Š” ๋งค์šฐ ํ’์š”๋กœ์šด
01:04
internal mental life and are so smart
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๋‚ด์  ์ •์‹  ์ƒํ™œ์„ ์˜์œ ํ•˜๊ณ  ๋˜ ์•„์ฃผ ์˜๋ฆฌํ•ด์„œ
01:06
that they choose not to let us realize it,
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์šฐ๋ฆฌ๊ฐ€ ๊ทธ ์‚ฌ์‹ค์„ ๊นจ๋‹ซ์ง€ ๋ชปํ•˜๊ฒŒ ํ•˜๊ธฐ๋กœ ์„ ํƒํ•œ ๊ฒƒ์ผ ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค.
01:10
but we eat them.
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ํ•˜์ง€๋งŒ ์šฐ๋ฆฌ๋Š” ์†Œ๋ฅผ ๋จน์ง€์š”.
01:11
I think most people will agree
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์ €๋Š” ๋Œ€๋ถ€๋ถ„์˜ ์‚ฌ๋žŒ๋“ค์ด
01:13
that chimps are capable of much more complex,
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์นจํŒฌ์ง€๊ฐ€ ์†Œ๋ณด๋‹ค ํ›จ์”ฌ ๋” ๋ณต์žกํ•˜๊ณ , ์ •๊ตํ•˜๊ณ ,
01:15
elaborate and flexible behaviors than cows are.
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๋˜ ์œ ์—ฐํ•œ ํ–‰๋™์„ ํ•  ์ˆ˜ ์žˆ๋‹ค๋Š” ์‚ฌ์‹ค์— ๋™์˜ํ•˜์‹ค ๊ฑฐ๋ผ ์ƒ๊ฐํ•ฉ๋‹ˆ๋‹ค
01:18
So this is a first indication that the
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๊ทธ๋ž˜์„œ ์ด ์‚ฌ์‹ค์€
01:20
"all brains are made the same way" scenario
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"๋ชจ๋“  ๋‡Œ๋Š” ๊ฐ™์€ ๋ฐฉ์‹์œผ๋กœ ๋งŒ๋“ค์–ด์ ธ ์žˆ๋‹ค" ๋ผ๋Š” ๊ฐ€์„ค์ด
01:22
is not quite right.
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๊ทธ๋‹ค์ง€ ๋งž์ง€๋Š” ์•Š๋‹ค๋ผ๋Š” ์ ์„ ๋‚˜ํƒ€๋‚ด๋Š” ์ฒซ ๋ฒˆ์งธ ํ‘œ์‹œ์ž…๋‹ˆ๋‹ค.
01:24
But let's play along.
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ํ•˜์ง€๋งŒ ์ผ๋‹จ ๋™์กฐํ•˜๋Š” ์ฒ™ ํ•ด๋ณด์ฃ .
01:25
If all brains were made the same way
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๊ทธ๋ž˜์„œ ๋งŒ์•ฝ ๋ชจ๋“  ๋‡Œ๊ฐ€ ๋™์ผํ•œ ๋ฐฉ์‹์œผ๋กœ ๋งŒ๋“ค์–ด์กŒ๊ณ 
01:27
and you were to compare animals with brains of different sizes,
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ํฌ๊ธฐ๊ฐ€ ๋‹ค๋ฅธ ๋‡Œ๋ฅผ ๊ฐ€์ง„ ๋™๋ฌผ๋“ค์„ ๋น„๊ตํ•œ๋‹ค๋ฉด
01:30
larger brains should always have more neurons
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ํฐ ๋‡Œ๋Š” ํ•ญ์ƒ ์ž‘์€ ๋‡Œ๋ณด๋‹ค
01:32
than smaller brains, and the larger the brain,
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๋” ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ์–ด์•ผ ํ•˜๊ณ  ๋˜ ๋‡Œ๊ฐ€ ํด์ˆ˜๋ก
01:34
the more cognitively able its owner should be.
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๊ทธ ์ฃผ์ธ์˜ ์ธ์ง€ ๋Šฅ๋ ฅ์€ ๋” ๋›ฐ์–ด๋‚˜์•ผ ํ•˜๊ฒ ์ฃ .
01:37
So the largest brain around should also be
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๊ทธ๋ž˜์„œ ๊ทธ ์ค‘์— ๊ฐ€์žฅ ํฐ ๋‡Œ์˜
01:39
the most cognitively able.
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์ธ์ง€ ๋Šฅ๋ ฅ์ด ๊ฐ€์žฅ ๋›ฐ์–ด๋‚˜์•ผ ํ•ฉ๋‹ˆ๋‹ค.
01:42
And here comes the bad news:
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๊ทธ๋Ÿฐ๋ฐ ์—ฌ๊ธฐ ์•ˆ ์ข‹์€ ์†Œ์‹์ด ํ•˜๋‚˜ ์žˆ์–ด์š”.
01:43
Our brain, not the largest one around.
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์šฐ๋ฆฌ์˜ ๋‡Œ๋Š” ๊ฐ€์žฅ ํฌ์ง€ ์•Š์Šต๋‹ˆ๋‹ค.
01:46
It seems quite vexing.
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๊ฝค ์„ฑ๊ฐ€์‹  ์ผ์ด์ฃ .
01:47
Our brain weighs between 1.2 and 1.5 kilos,
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์šฐ๋ฆฌ ๋‡Œ์˜ ๋ฌด๊ฒŒ๋Š” 1.2์—์„œ 1.5ํ‚ฌ๋กœ๊ทธ๋žจ ์ •๋„์ด์ง€๋งŒ
01:50
but elephant brains weigh between four and five kilos,
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์ฝ”๋ผ๋ฆฌ์˜ ๋‡Œ๋Š” 4์—์„œ 5ํ‚ฌ๋กœ๊ทธ๋žจ ์ •๋„ ๋˜์š”.
01:54
and whale brains can weigh up to nine kilos,
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๊ทธ๋ฆฌ๊ณ  ๊ณ ๋ž˜์˜ ๋‡Œ๋Š” 9ํ‚ฌ๋กœ๊ทธ๋žจ๊นŒ์ง€ ๋‚˜๊ฐ€๊ธฐ๋„ ํ•ฉ๋‹ˆ๋‹ค.
01:56
which is why scientists used to resort to saying
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์ด๋กœ ์ธํ•ด ๊ณผํ•™์ž๋“ค์€ ์šฐ๋ฆฌ์˜ ์ธ์ง€ ๋Šฅ๋ ฅ์„ ์„ค๋ช…ํ•˜๊ธฐ ์œ„ํ•ด
02:01
that our brain must be special
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์šฐ๋ฆฌ์˜ ๋‡Œ๊ฐ€ ํŠน๋ณ„ํ•  ๊ฒƒ์ด๋ผ๊ณ 
02:03
to explain our cognitive abilities.
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๋งํ•˜๊ณค ํ–ˆ์Šต๋‹ˆ๋‹ค.
02:06
It must be really extraordinary,
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์ธ๊ฐ„์˜ ๋‡Œ๋Š” ์ •๋ง ํŠน๋ณ„ํ•ด์„œ
02:09
an exception to the rule.
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๋ฒ•์น™์— ์˜ˆ์™ธ๊ฐ€ ๋œ๋‹ค๊ณ  ๋ง์ด์ฃ .
02:11
Theirs may be bigger, but ours is better,
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๋” ํฐ ๋‡Œ๊ฐ€ ์žˆ์„ ์ˆ˜ ์žˆ์ง€๋งŒ ์šฐ๋ฆฌ์˜ ๋‡Œ๊ฐ€ ๋” ๋‚ซ๋‹ค๋Š” ๊ฒ๋‹ˆ๋‹ค.
02:14
and it could be better, for example,
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์˜ˆ๋ฅผ ๋“ค๋ฉด
02:16
in that it seems larger than it should be,
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์›๋ž˜ ๋ณด์—ฌ์•ผ ํ•˜๋Š” ๊ฒƒ๋ณด๋‹ค ๋” ์ปค ๋ณด์ด๊ณ 
02:18
with a much larger cerebral cortex than we should have
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์šฐ๋ฆฌ ๋ชธ์˜ ํฌ๊ธฐ์— ๋น„ํ•ด
02:21
for the size of our bodies.
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ํ›จ์”ฌ ๋” ํฐ ๋Œ€๋‡Œ ํ”ผ์งˆ์„ ๊ฐ–๊ณ  ์žˆ๋‹ค๋Š” ์ ์—์„œ ๋‚ซ๋‹ค๋Š” ๊ฑฐ์—์š”.
02:22
So that would give us extra cortex
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๊ทธ๋ž˜์„œ ๋‹จ์ง€ ์‹ ์ฒด๋ฅผ ์ž‘๋™์‹œํ‚ค๋Š” ๊ฒƒ๋ณด๋‹ค
02:24
to do more interesting things than just operating the body.
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๋” ์žฌ๋ฏธ์žˆ๋Š” ์ผ์„ ํ•  ์ˆ˜ ์žˆ๊ฒŒ ํ•˜๋Š” ์—ฌ๋ถ„์˜ ๋Œ€๋‡Œ ํ”ผ์งˆ์„ ๊ฐ–๊ฒŒ ๋œ๊ฑฐ์ฃ .
02:27
That's because the size of the brain
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์™œ๋ƒํ•˜๋ฉด ๋‡Œ์˜ ํฌ๊ธฐ๋Š”
02:29
usually follows the size of the body.
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๋ณดํ†ต ์‹ ์ฒด ์‚ฌ์ด์ฆˆ์— ๋น„๋ก€ํ•˜๊ธฐ ๋•Œ๋ฌธ์ž…๋‹ˆ๋‹ค.
02:31
So the main reason for saying that
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๊ทธ๋ž˜์„œ ์šฐ๋ฆฌ์˜ ๋‡Œ๊ฐ€ ํ•„์š” ์ด์ƒ์œผ๋กœ ํฌ๋‹ค๊ณ 
02:33
our brain is larger than it should be
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์ด์•ผ๊ธฐํ•˜๋Š” ์ฃผ๋œ ์ด์œ ๋Š”
02:35
actually comes from comparing ourselves
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์šฐ๋ฆฌ ์ž์‹ ์„ ์œ ์ธ์›๊ณผ ๋น„๊ตํ•˜๋Š” ๊ฒƒ์—์„œ
02:37
to great apes.
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๋น„๋กฏ๋ฉ๋‹ˆ๋‹ค.
02:39
Gorillas can be two to three times larger than we are,
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๊ณ ๋ฆด๋ผ๋Š” ์šฐ๋ฆฌ๋ณด๋‹ค ๋‘์„ธ ๋ฐฐ ๋” ํด ์ˆ˜ ์žˆ๊ธฐ ๋•Œ๋ฌธ์—
02:41
so their brains should also be larger than ours,
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๊ทธ๋“ค์˜ ๋‡Œ๋„ ์šฐ๋ฆฌ์˜ ๊ฒƒ๋ณด๋‹ค ์ปค์•ผ ํ•˜์ง€๋งŒ
02:44
but instead it's the other way around.
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์‚ฌ์‹ค์€ ๊ทธ ๋ฐ˜๋Œ€์—์š”.
02:46
Our brain is three times larger than a gorilla brain.
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๊ณ ๋ฆด๋ผ์˜ ๋‡Œ๋ณด๋‹ค ์šฐ๋ฆฌ์˜ ๋‡Œ๊ฐ€ ์„ธ ๋ฐฐ ๋” ํฝ๋‹ˆ๋‹ค.
02:49
The human brain also seems special
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์ธ๊ฐ„์˜ ๋‡Œ๊ฐ€ ์‚ฌ์šฉํ•˜๋Š” ์—๋„ˆ์ง€์˜ ์–‘๋„
02:51
in the amount of energy that it uses.
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ํŠน๋ณ„ํ•ด ๋ณด์ž…๋‹ˆ๋‹ค.
02:53
Although it weighs only two percent of the body,
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๋‡Œ๋Š” ๊ณ ์ž‘ ์ฒด์ค‘์˜ 2ํผ์„ผํŠธ ๋งŒ์„ ์ฐจ์ง€ํ•˜์ง€๋งŒ
02:56
it alone uses 25 percent of all the energy
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ํ˜ผ์ž์„œ ์‹ ์ฒด๊ฐ€ ํ•˜๋ฃจ์— ํ•„์š”๋กœ ํ•˜๋Š”
02:59
that your body requires to run per day.
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์ „์ฒด ์—๋„ˆ์ง€์˜ 25ํผ์„ผํŠธ๋ฅผ ์‚ฌ์šฉํ•ฉ๋‹ˆ๋‹ค.
03:02
That's 500 calories out of a total of 2,000 calories,
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์ด 2,000 ์นผ๋กœ๋ฆฌ ์ค‘ 500 ์นผ๋กœ๋ฆฌ๊ฐ€
03:05
just to keep your brain working.
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๋‡Œ๋ฅผ ์ž‘์šฉํ•˜๋Š”๋ฐ ์“ด๋‹ค๋Š” ๊ฑฐ์ฃ .
03:07
So the human brain is larger than it should be,
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์ธ๊ฐ„์˜ ๋‡Œ๋Š” ํ•„์š” ์ด์ƒ์œผ๋กœ ํฌ๊ณ 
03:10
it uses much more energy than it should,
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ํ•„์š” ์ด์ƒ์œผ๋กœ ๋งŽ์€ ์—๋„ˆ์ง€๋ฅผ ์‚ฌ์šฉํ•˜๊ธฐ์—
03:12
so it's special.
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ํŠน๋ณ„ํ•œ ๊ฒ๋‹ˆ๋‹ค.
03:14
And this is where the story started to bother me.
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์—ฌ๊ธฐ์„œ๋ถ€ํ„ฐ ์‹ ๊ฒฝ์ด ์“ฐ์ด๋”๊ตฐ์š”.
03:16
In biology, we look for rules
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์ƒ๋ฌผํ•™์—์„œ ์šฐ๋ฆฌ๋Š” ์ „์ฒด์ ์œผ๋กœ ๋ชจ๋“  ๋™๋ฌผ๊ณผ ์ƒ๋ช…์—
03:18
that apply to all animals and to life in general,
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์ ์šฉ๋˜๋Š” ๋ฒ•์น™์„ ์ฐพ์Šต๋‹ˆ๋‹ค.
03:21
so why should the rules of evolution
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๊ทธ๋Ÿผ ์™œ ์ง„ํ™”์˜ ๋ฒ•์น™์€
03:23
apply to everybody else but not to us?
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๋‹ค๋ฅธ ๋ชจ๋‘์—๊ฒŒ ์ ์šฉ๋˜์ง€๋งŒ ์šฐ๋ฆฌ์—๊ฒ ๊ทธ๋Ÿฌ์ง€ ์•Š์„๊นŒ์š”?
03:26
Maybe the problem was with the basic assumption
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์•„๋งˆ ๋ฌธ์ œ๋Š” ๋ชจ๋“  ๋‡Œ๋“ค์€
03:29
that all brains are made in the same way.
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๊ฐ™์€ ๋ฐฉ์‹์œผ๋กœ ๋งŒ๋“ค์–ด์ ธ ์žˆ๋‹ค๋Š” ๊ธฐ์ดˆ์  ๊ฐ€์ •์— ์žˆ์—ˆ๋˜ ๊ฒƒ ๊ฐ™์Šต๋‹ˆ๋‹ค.
03:30
Maybe two brains of a similar size
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์–ด์ฉŒ๋ฉด ๋น„์Šทํ•œ ํฌ๊ธฐ์˜ ๋‘ ๋‡Œ๊ฐ€
03:32
can actually be made of very different numbers of neurons.
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์‹ค์ œ๋กœ๋Š” ๋งค์šฐ ๋‹ค๋ฅธ ์ˆ˜์˜ ์‹ ๊ฒฝ ์„ธํฌ๋กœ ์ด๋ฃจ์–ด์งˆ ์ˆ˜๋„ ์žˆ๋‹ค๋Š” ๊ฑฐ์ฃ .
03:35
Maybe a very large brain
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ํ˜น์€ ๋งค์šฐ ํฐ ๋‡Œ๊ฐ€
03:36
does not necessarily have more neurons
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์ž‘์€ ํฌ๊ธฐ์˜ ๋‡Œ๋ณด๋‹ค
03:38
than a more modest-sized brain.
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์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๋” ๋งŽ์ด ๊ฐ€์ง€๊ณ  ์žˆ์ง€ ์•Š์„ ์ˆ˜๋„ ์žˆ๊ณ ์š”.
03:40
Maybe the human brain actually has the most neurons
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์•„๋‹ˆ๋ฉด ์ธ๊ฐ„์˜ ๋‡Œ๋Š” ์‹ค์ œ๋กœ
03:43
of any brain, regardless of its size,
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ํฌ๊ธฐ์™€ ์ƒ๊ด€์—†์ด ๋ชจ๋“  ๋‡Œ ์ค‘์—์„œ, ํŠนํžˆ ๋Œ€๋‡Œ ํ”ผ์งˆ์—
03:46
especially in the cerebral cortex.
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๊ฐ€์žฅ ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ์„ ์ง€๋„ ๋ชฐ๋ผ์š”.
03:48
So this to me became
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์ด๊ฒƒ์€ ์ €์—๊ฒŒ
03:50
the important question to answer:
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๋‹ตํ•ด์•ผ ํ•  ์ค‘์š”ํ•œ ์งˆ๋ฌธ์ด ๋˜์—ˆ์–ด์š”.
03:51
how many neurons does the human brain have,
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์ธ๊ฐ„์˜ ๋‡Œ๋Š” ์–ผ๋งˆ๋‚˜ ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋กœ ์ด๋ฃจ์–ด์ ธ ์žˆ๊ณ 
03:54
and how does that compare to other animals?
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๊ทธ ์ˆ˜๋Š” ๋‹ค๋ฅธ ๋™๋ฌผ๋“ค๊ณผ ๋น„๊ตํ–ˆ์„ ๋•Œ ์–ด๋– ํ•œ๊ฐ€?
03:56
Now, you may have heard or read somewhere
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์—ฌ๋Ÿฌ๋ถ„์€ ์•„๋งˆ ์–ด๋””์„ ๊ฐ€
03:59
that we have 100 billion neurons,
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์šฐ๋ฆฌ๊ฐ€ 1,000์–ต ๊ฐœ์˜ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ๋‹ค๊ณ  ๋“ค์—ˆ๊ฑฐ๋‚˜ ์ฝ์€ ์ ์ด ์žˆ์„ ๊ฑฐ์—์š”.
04:01
so 10 years ago, I asked my colleagues
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๊ทธ๋ž˜์„œ ์ „ 10๋…„ ์ „, ๋™๋ฃŒ๋“ค์—๊ฒŒ ๋ฌผ์—ˆ์Šต๋‹ˆ๋‹ค.
04:03
if they knew where this number came from.
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์ด ์ˆซ์ž์˜ ์ถœ์ฒ˜๊ฐ€ ์–ด๋”˜์ง€ ์•„๋Š”๊ฐ€ ํ•˜๊ณ ์š”.
04:05
But nobody did.
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ํ•˜์ง€๋งŒ ์•„๋ฌด๋„ ๋ชฐ๋ž์–ด์š”.
04:06
I've been digging through the literature
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์ €๋Š” ๊ทธ ์ˆซ์ž์˜ ์ถœ์ฒ˜๋ฅผ ์ฐพ๊ธฐ ์œ„ํ•ด
04:08
for the original reference for that number,
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์ฐธ๊ณ  ๋ฌธํ—Œ์„ ๋’ค์ ธ๋ดค์ง€๋งŒ
04:10
and I could never find it.
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์ฐพ์„ ์ˆ˜ ์—†์—ˆ์Šต๋‹ˆ๋‹ค.
04:11
It seems that nobody had actually ever counted
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๊ทธ ๋ˆ„๊ตฌ๋„
04:14
the number of neurons in the human brain,
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์‚ฌ๋žŒ์˜ ๋‡Œ์— ์žˆ๋Š” ์‹ ๊ฒฝ ์„ธํฌ์˜ ์ˆ˜๋‚˜
04:16
or in any other brain for that matter.
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๋‹ค๋ฅธ ๋‡Œ์˜ ์‹ ๊ฒฝ ์„ธํฌ ์ˆ˜๋ฅผ ์„ธ์–ด๋ณธ ์ ์ด ์—†๋Š” ๊ฒƒ ๊ฐ™์Šต๋‹ˆ๋‹ค.
04:18
So I came up with my own way to count cells in the brain,
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๊ทธ๋ž˜์„œ ์ €๋Š” ์„ธํฌ๋ฅผ ์„ธ๋Š” ์ €๋งŒ์˜ ๋ฐฉ๋ฒ•์„ ์ƒ๊ฐํ•ด ๋ƒˆ์–ด์š”.
04:22
and it essentially consists of
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์ด๋Š” ๊ธฐ๋ณธ์ ์œผ๋กœ
04:24
dissolving that brain into soup.
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๋‡Œ๋ฅผ ์šฉํ•ด์‹œ์ผœ ์ˆ˜ํ”„์ฒ˜๋Ÿผ ๋งŒ๋“œ๋Š” ๊ฒ๋‹ˆ๋‹ค.
04:27
It works like this:
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์ด๋Ÿฐ ์‹์ด์—์š”.
04:29
You take a brain, or parts of that brain,
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๋‡Œ ํ˜น์€ ๋‡Œ์˜ ์ผ๋ถ€๋ถ„์„
04:32
and you dissolve it in detergent,
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์„ธ์ œ๋กœ ๋…น์ž…๋‹ˆ๋‹ค.
04:34
which destroys the cell membranes
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์„ธ์ œ๋Š” ์„ธํฌ๋ง‰์„ ํŒŒ๊ดดํ•˜์ง€๋งŒ
04:35
but keeps the cell nuclei intact,
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์„ธํฌํ•ต์€ ์†์ƒ์‹œํ‚ค์ง€ ์•Š์•„์„œ
04:38
so you end up with a suspension of free nuclei
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์„ธํฌํ•ต์œผ๋กœ ์ด๋ฃจ์–ด์ง„
04:41
that looks like this,
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๋ง‘์€ ์ˆ˜ํ”„์ฒ˜๋Ÿผ ๋ณด์ด๋Š”
04:43
like a clear soup.
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ํ˜„ํƒ์•ก์„ ์–ป๊ฒŒ ๋˜์ฃ .
04:44
This soup contains all the nuclei
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์ด ์•ก์ฒด์—๋Š” ํ•œ ๋•Œ ์ฅ์˜ ๋‡Œ์˜€๋˜
04:46
that once were a mouse brain.
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๋ชจ๋“  ์„ธํฌํ•ต์ด ๋“ค์–ด์žˆ์–ด์š”.
04:48
Now, the beauty of a soup is that because it is soup,
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์ด ์ˆ˜ํ”„์˜ ์žฅ์ ์€ ์•ก์ฒด์ด๊ธฐ ๋•Œ๋ฌธ์—
04:51
you can agitate it and make those nuclei
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์ž˜ ํœ˜์ €์–ด์„œ
04:54
be distributed homogeneously in the liquid,
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์•ก์ฒด ๋‚ด์˜ ์„ธํฌํ•ต์„ ๊ท ์ผํ•˜๊ฒŒ ํผ๋œจ๋ฆด ์ˆ˜ ์žˆ๋‹ค๋Š” ๊ฑฐ์—์š”.
04:56
so that now by looking under the microscope
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๊ทธ๋ฆฌ๊ณ  ํ˜„๋ฏธ๊ฒฝ์œผ๋กœ
04:58
at just four or five samples of this homogeneous solution,
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๊ท ์ผ ์šฉ์•ก์˜ ํ‘œ๋ณธ์„ 4, 5๊ฐœ ์ •๋„๋งŒ ๊ด€์ฐฐํ•˜์—ฌ
05:02
you can count nuclei, and therefore tell
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ํ•ต์˜ ์ˆ˜๋ฅผ ์„ผ๋‹ค๋ฉด
05:05
how many cells that brain had.
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๊ทธ ๋‡Œ์˜ ์„ธํฌ์ˆ˜๋ฅผ ์•Œ ์ˆ˜ ์žˆ๋Š”๊ฑฐ์ฃ 
05:06
It's simple, it's straightforward,
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์ด ๋ฐฉ๋ฒ•์€ ๊ฐ„๋‹จํ•˜๊ณ  ๋ช…๋ฃŒํ•œ ๋ฐ๋‹ค๊ฐ€
05:08
and it's really fast.
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์ •๋ง ๋นจ๋ผ์š”.
05:09
So we've used that method to count neurons
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๊ทธ๋ž˜์„œ ์šฐ๋ฆฐ ์ด ๋ฐฉ๋ฒ•์„ ์‚ฌ์šฉํ•ด
05:11
in dozens of different species so far,
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์ˆ˜์‹ญ ์ข…์˜ ์‹ ๊ฒฝ ์„ธํฌ์ˆ˜๋ฅผ ์„ธ์—ˆ๊ณ 
05:14
and it turns out that all brains
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๊ทธ๋กœ ์ธํ•ด ๋ชจ๋“  ๋‡Œ๋“ค์ด
05:15
are not made the same way.
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๊ฐ™์€ ๋ฐฉ์‹์œผ๋กœ ๋งŒ๋“ค์–ด์ง€์ง€ ์•Š์•˜๋‹ค๋Š” ์‚ฌ์‹ค์„ ์•Œ์•„๋ƒˆ์Šต๋‹ˆ๋‹ค.
05:18
Take rodents and primates, for instance:
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์„ค์น˜๋ฅ˜์™€ ์œ ์ธ์›์„ ์˜ˆ๋กœ ๋“ค์–ด๋ณด์ฃ .
05:20
In larger rodent brains, the average size
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ํฐ ์„ค์น˜๋ฅ˜์˜ ๋‡Œ์—๋Š”
05:22
of the neuron increases,
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์‹ ๊ฒฝ ์„ธํฌ์˜ ํ‰๊ท  ํฌ๊ธฐ๊ฐ€ ์ฆ๊ฐ€ํ•˜์—ฌ
05:24
so the brain inflates very rapidly
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๋‡Œ๋Š” ๋งค์šฐ ๋นจ๋ฆฌ ํŒฝ์ฐฝํ•˜๊ณ 
05:27
and gains size much faster than it gains neurons.
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์‹ ๊ฒฝ ์„ธํฌ์ˆ˜๋ฅผ ๋Š˜๋ฆฌ๋Š” ์†๋„๋ณด๋‹ค ํ›จ์”ฌ ๋น ๋ฅด๊ฒŒ ์ปค์ง‘๋‹ˆ๋‹ค.
05:30
But primate brains gain neurons
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ํ•˜์ง€๋งŒ ์œ ์ธ์›์˜ ๋‡Œ๊ฐ€ ์‹ ๊ฒฝ ์„ธํฌ์ˆ˜๋ฅผ ๋Š˜๋ฆด ๋•Œ๋Š”
05:32
without the average neuron becoming any larger,
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์‹ ๊ฒฝ ์„ธํฌ์˜ ํ‰๊ท  ํฌ๊ธฐ๊ฐ€ ๋”์ด์ƒ ์ปค์ง€์ง€ ์•Š์•„์š”.
05:34
which is a very economical way
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์ด๊ฒƒ์ด ๋‡Œ์— ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ์ถ”๊ฐ€ํ•˜๋Š”
05:35
to add neurons to your brain.
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๋งค์šฐ ์‹ค์† ์žˆ๋Š” ๋ฐฉ๋ฒ•์ž…๋‹ˆ๋‹ค.
05:37
The result is that a primate brain
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์œ ์ธ์›์˜ ๋‡Œ๋Š” ํ•ญ์ƒ
05:39
will always have more neurons than a rodent brain of the same size,
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๊ฐ™์€ ํฌ๊ธฐ์˜ ์„ค์น˜๋ฅ˜์˜ ๋‡Œ๋ณด๋‹ค ๋” ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง€๊ฒŒ ๋˜๊ณ 
05:42
and the larger the brain,
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๋‡Œ๊ฐ€ ๋” ํด์ˆ˜๋ก
05:44
the larger this difference will be.
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๊ทธ ์ฐจ์ด๋„ ๋” ์ปค์ง€๊ฒŒ ๋˜๋Š” ๊ฒฐ๊ณผ๋ฅผ ๋‚ณ์ฃ .
05:46
Well, what about our brain then?
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์šฐ๋ฆฌ์˜ ๋‡Œ๋Š” ์–ด๋–จ๊นŒ์š”?
05:48
We found that we have, on average,
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์šฐ๋ฆฌ๋Š” ํ‰๊ท ์ ์œผ๋กœ
05:50
86 billion neurons,
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860์–ต ๊ฐœ์˜ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ์Œ์„ ์•Œ์•„๋ƒˆ์Šต๋‹ˆ๋‹ค.
05:51
16 billion of which are in the cerebral cortex,
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๊ทธ์ค‘ 160์–ต ๊ฐœ๋Š” ๋Œ€๋‡Œ ํ”ผ์งˆ์— ์žˆ๊ณ 
05:54
and if you consider that the cerebral cortex
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๋Œ€๋‡Œ ํ”ผ์งˆ์ด
05:56
is the seat of functions like
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์˜์‹์ , ๋…ผ๋ฆฌ์  ๊ทธ๋ฆฌ๊ณ  ์ถ”์ƒ์  ์‚ฌ๊ณ ์™€ ๊ฐ™์€
06:00
awareness and logical and abstract reasoning,
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๊ธฐ๋Šฅ์„ ํ•˜๋Š” ๊ฒƒ์„ ๊ณ ๋ คํ•˜๋‹ค๋ฉด
06:03
and that 16 billion is the most neurons
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๊ทธ๋ฆฌ๊ณ  ๋Œ€๋‡Œ ํ”ผ์งˆ์ด ๊ฐ€์งˆ ์ˆ˜ ์žˆ๋Š” ์‹ ๊ฒฝ ์„ธํฌ์˜ ์ˆ˜๊ฐ€
06:06
that any cortex has,
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์ตœ๋Œ€ 160์–ต ๊ฐœ๋ผ๋Š” ์ ์„ ์ƒ๊ฐํ•ด๋ณธ๋‹ค๋ฉด
06:08
I think this is the simplest explanation
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์ด๊ฒƒ์ด ์šฐ๋ฆฌ๊ฐ€ ๊ฐ€์ง„ ๋†€๋ผ์šด ์ธ์ง€ ๋Šฅ๋ ฅ์— ๋Œ€ํ•œ
06:10
for our remarkable cognitive abilities.
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๊ฐ€์žฅ ๊ฐ„๋‹จํ•œ ์„ค๋ช…์ด๋ผ๊ณ  ์ƒ๊ฐํ•ฉ๋‹ˆ๋‹ค.
06:13
But just as important is what the 86 billion neurons mean.
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ํ•˜์ง€๋งŒ 860์–ต ๊ฐœ์˜ ์‹ ๊ฒฝ ์„ธํฌ๊ฐ€ ๋œปํ•˜๋Š” ๋ฐ”๋„ ์ค‘์š”ํ•ด์š”.
06:16
Because we found that the relationship
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์šฐ๋ฆฌ๋Š” ๋‡Œ์˜ ํฌ๊ธฐ์™€
06:18
between the size of the brain and its number of neurons
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์‹ ๊ฒฝ ์„ธํฌ ์ˆ˜ ์‚ฌ์ด์˜ ๊ด€๊ณ„๋ฅผ
06:20
could be described mathematically,
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์ˆ˜ํ•™์ ์œผ๋กœ ์„ค๋ช…ํ•  ์ˆ˜ ์žˆ๋‹ค๋Š” ๊ฑธ ์•Œ์•„๋ƒˆ๊ธฐ ๋•Œ๋ฌธ์—
06:22
we could calculate what a human brain
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๋งŒ์•ฝ ์šฐ๋ฆฌ ๋‡Œ๊ฐ€ ์„ค์น˜๋ฅ˜์˜ ๋‡Œ์ฒ˜๋Ÿผ ๋งŒ๋“ค์–ด์กŒ๋‹ค๋ฉด
06:24
would look like if it was made like a rodent brain.
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๊ทธ ๋ชจ์Šต์ด ์–ด๋–จ์ง€ ๊ณ„์‚ฐํ•  ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค.
06:27
So, a rodent brain with 86 billion neurons
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860์–ต๊ฐœ์˜ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง„ ์„ค์น˜๋ฅ˜์˜ ๋‡Œ์˜ ๋ฌด๊ฒŒ๋Š”
06:30
would weigh 36 kilos.
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36 ํ‚ฌ๋กœ๊ทธ๋žจ์ผ ๊ฒ๋‹ˆ๋‹ค.
06:33
That's not possible.
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๋ง์ด ์•ˆ๋˜์ฃ .
06:35
A brain that huge would be crushed
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๊ทธ ์ •๋„๋กœ ํฐ ๋‡Œ๋Š”
06:37
by its own weight,
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์ž์ฒด์˜ ๋ฌด๊ฒŒ๋กœ ์œผ์Šค๋Ÿฌ์งˆ ๊ฑฐ๊ณ 
06:38
and this impossible brain would go
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๋˜ ์ด ๋ง๋„ ์•ˆ ๋˜๋Š” ๋‡Œ๋Š”
06:40
in the body of 89 tons.
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89 ํ†ค์งœ๋ฆฌ ๋ชธ์—๋‚˜ ์–ด์šธ๋ฆด ๊ฑฐ์—์š”.
06:44
I don't think it looks like us.
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ํ˜„์žฌ์˜ ์šฐ๋ฆฌ์ฒ˜๋Ÿผ ๋ณด์ด์ง€ ์•Š์„ ๊ฑฐ๋ผ ์ƒ๊ฐํ•ฉ๋‹ˆ๋‹ค.
06:46
So this brings us to a very important conclusion already,
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์ด ์‚ฌ์‹ค์€ ์•„์ฃผ ์ค‘์š”ํ•œ ๊ฒฐ๋ก ์„ ์ด๋Œ์–ด๋ƒ…๋‹ˆ๋‹ค.
06:48
which is that we are not rodents.
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์šฐ๋ฆฌ๋Š” ์„ค์น˜๋ฅ˜๊ฐ€ ์•„๋‹ˆ๋ผ๋Š” ๊ฒƒ์ด์ฃ .
06:51
The human brain is not a large rat brain.
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์‚ฌ๋žŒ์˜ ๋‡Œ๋Š” ์ปค๋‹ค๋ž€ ์„ค์น˜๋ฅ˜์˜ ๋‡Œ๊ฐ€ ์•„๋‹™๋‹ˆ๋‹ค.
06:54
Compared to a rat, we might seem special, yes,
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์šฐ๋ฆฌ๋Š” ์ฅ์— ๋น„ํ•ด ํŠน๋ณ„ํ•ด ๋ณด์ผ์ง€ ๋ชจ๋ฅด์ง€๋งŒ
06:57
but that's not a fair comparison to make,
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์šฐ๋ฆฌ๊ฐ€ ์„ค์น˜๋ฅ˜๊ฐ€ ์•„๋‹˜์„ ์•Œ๊ณ  ์žˆ๋Š” ์ƒํƒœ์—์„ 
06:59
given that we know that we are not rodents.
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ํƒ€๋‹นํ•œ ๋น„๊ต๊ฐ€ ๋  ์ˆ˜ ์—†์–ด์š”.
07:01
We are primates,
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์šฐ๋ฆฌ๋Š” ์˜์žฅ๋ฅ˜์ด๊ณ 
07:02
so the correct comparison is to other primates.
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๊ทธ๋Ÿฌ๊ธฐ์— ๋‹ค๋ฅธ ์˜์žฅ๋ฅ˜์™€ ๋น„๊ต๋˜์–ด์•ผ ํ•ฉ๋‹ˆ๋‹ค.
07:05
And there, if you do the math,
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๊ฑฐ๊ธฐ์„œ ๊ณ„์‚ฐ์„ ํ•ด๋ณด๋ฉด
07:06
you find that a generic primate
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์ผ๋ฐ˜์ ์ธ ์˜์žฅ๋ฅ˜๋กœ์„œ
07:09
with 86 billion neurons
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860์–ต ๊ฐœ์˜ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ๋‹ค๋ฉด
07:11
would have a brain of about 1.2 kilos,
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๋‡Œ๋Š” ์•ฝ 1.2 ํ‚ฌ๋กœ๊ทธ๋žจ์ผ ๊ฒƒ์ž…๋‹ˆ๋‹ค
07:14
which seems just right,
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66 ํ‚ฌ๋กœ๊ทธ๋žจ์˜ ์‹ ์ฒด์—
07:16
in a body of some 66 kilos,
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์ ๋‹นํ•ด ๋ณด์ด์ฃ .
07:18
which in my case is exactly right,
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์ œ ๊ฒฝ์šฐ์—” ์ •ํ™•ํžˆ ๋“ค์–ด๋งž์•„์š”.
07:21
which brings us to a very unsurprising
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์ด ์‚ฌ์‹ค์€ ์•„์ฃผ ๋†€๋ž์ง€๋Š” ์•Š์ง€๋งŒ
07:23
but still incredibly important conclusion:
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์—ฌ์ „ํžˆ ์ค‘์š”ํ•œ ๊ฒฐ๋ก ์œผ๋กœ ์šฐ๋ฆด ์ด๋•๋‹ˆ๋‹ค.
07:26
I am a primate.
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๋ฐ”๋กœ ์ œ๊ฐ€ ์˜์žฅ๋ฅ˜๋ผ๋Š” ๊ฒƒ์ด์ฃ .
07:28
And all of you are primates.
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์—ฌ๋Ÿฌ๋ถ„๋„ ๋ชจ๋‘ ์˜์žฅ๋ฅ˜์ด๊ณ ์š”.
07:30
And so was Darwin.
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๋‹ค์œˆ๋„ ๊ทธ๋žฌ์ฃ .
07:32
I love to think that Darwin would have really appreciated this.
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์ €๋Š” ๋‹ค์œˆ์ด ์ด ์‚ฌ์‹ค์— ์•„์ฃผ ๊ฐ์‚ฌํ–ˆ์„ ๊ฑฐ๋ผ๊ณ  ์ƒ๊ฐํ•ด์š”.
07:35
His brain, like ours,
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๋‹ค์œˆ์˜ ๋‡Œ๋Š” ์šฐ๋ฆฌ ๋‡Œ์ฒ˜๋Ÿผ
07:37
was made in the image of other primate brains.
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๋‹ค๋ฅธ ์˜์žฅ๋ฅ˜์˜ ๋‡Œ์™€ ๊ฐ™๊ฒŒ ๋งŒ๋“ค์–ด์กŒ์—ˆ์Šต๋‹ˆ๋‹ค.
07:41
So the human brain may be remarkable, yes,
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์‚ฌ๋žŒ์˜ ๋‡Œ๋Š” ์•„๋งˆ ํ›Œ๋ฅญํ•  ๊ฑฐ์˜ˆ์š”.
07:43
but it is not special in its number of neurons.
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ํ•˜์ง€๋งŒ ์ด ๋‡Œ๊ฐ€ ๊ฐ€์ง„ ์‹ ๊ฒฝ ์„ธํฌ์˜ ์ˆ˜๋Š” ํŠน๋ณ„ํ•˜์ง€ ์•Š์Šต๋‹ˆ๋‹ค.
07:46
It is just a large primate brain.
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๊ทธ์ € ์ปค๋‹ค๋ž€ ์˜์žฅ๋ฅ˜์˜ ๋‡Œ์ผ ๋ฟ์ด์ฃ .
07:48
I think that's a very humbling and sobering thought
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์ €๋Š” ์ด ๊ฒธ์†ํ•˜๊ณ  ์ •์‹ ์„ ์ผ๊นจ์šฐ๋Š” ์‚ฌ์‹ค์ด
07:51
that should remind us of our place in nature.
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์ž์—ฐ ๋‚ด์˜ ์šฐ๋ฆฌ ์œ„์น˜๋ฅผ ์ƒ๊ธฐ์‹œ์ผœ์ค€๋‹ค๊ณ  ์ƒ๊ฐํ•ด์š”.
07:54
Why does it cost so much energy, then?
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๊ทธ๋ ‡๋‹ค๋ฉด ์™œ ๊ทธ๋ ‡๊ฒŒ ๋งŽ์€ ์—๋„ˆ์ง€๋ฅผ ํ•„์š”๋กœ ํ• ๊นŒ์š”?
07:56
Well, other people have figured out
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๋‹ค๋ฅธ ์‚ฌ๋žŒ๋“ค์€
07:58
how much energy the human brain
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์ธ๊ฐ„์˜ ๋‡Œ์™€
07:59
and that of other species costs,
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๋‹ค๋ฅธ ์ข…์˜ ๋‡Œ๊ฐ€ ์†Œ๋น„ํ•˜๋Š” ์—๋„ˆ์ง€ ์–‘์„ ์•Œ์•„๋ƒˆ๊ณ 
08:01
and now that we knew how many neurons
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์šฐ๋ฆฌ๋Š” ์ด์ œ ๊ฐ ๋‡Œ๊ฐ€ ์–ผ๋งˆ๋‚˜ ๋งŽ์€
08:02
each brain was made of, we could do the math.
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์‹ ๊ฒฝ ์„ธํฌ๋กœ ์ด๋ฃจ์–ด์กŒ๋Š”์ง€ ์•„๋‹ˆ๊นŒ ๊ณ„์‚ฐํ•  ์ˆ˜ ์žˆ์–ด์š”.
08:05
And it turns out that both human
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์‚ฌ๋žŒ์˜ ๋‡Œ์™€
08:07
and other brains cost about the same,
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๋‹ค๋ฅธ ๋‡Œ๊ฐ€ ์†Œ๋น„ํ•˜๋Š” ์—๋„ˆ์ง€๋Š” ๊ฑฐ์˜ ๊ฐ™๋‹ค๊ณ  ๋ฐํ˜€์กŒ์Šต๋‹ˆ๋‹ค.
08:09
an average of six calories per billion neurons per day.
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10์–ต ๊ฐœ์˜ ์‹ ๊ฒฝ ์„ธํฌ๋Š” ํ•˜๋ฃจ์— ํ‰๊ท  6 ์นผ๋กœ๋ฆฌ๋ฅผ ์†Œ๋น„ํ•ด์š”.
08:13
So the total energetic cost of a brain
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๋‡Œ๊ฐ€ ์†Œ๋น„ํ•˜๋Š” ์ „์ฒด ์—๋„ˆ์ง€๋Š”
08:15
is a simple, linear function
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์‹ ๊ฒฝ ์„ธํฌ ์ˆ˜์— ๋Œ€ํ•œ
08:17
of its number of neurons,
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๋‹จ์ˆœํ•œ ์„ ํ˜• ํ•จ์ˆ˜์ด๊ณ 
08:19
and it turns out that the human brain
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์—ฌ๋Ÿฌ๋ถ„์ด ์˜ˆ์ƒํ•˜์…จ๋˜ ๋Œ€๋กœ ์‚ฌ๋žŒ์˜ ๋‡Œ๋Š”
08:21
costs just as much energy as you would expect.
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๋งŽ์€ ์—๋„ˆ์ง€๋ฅผ ์†Œ๋น„ํ•˜๋Š” ๊ฒƒ์ด์ฃ .
08:25
So the reason why the human brain
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์‚ฌ๋žŒ์˜ ๋‡Œ๊ฐ€
08:27
costs so much energy is simply because
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๊ทธ๋Ÿฐ๊ฒŒ ํฐ ์—๋„ˆ์ง€๋ฅผ ์†Œ๋น„ํ•˜๋Š” ์ด์œ ๋Š”
08:28
it has a huge number of neurons,
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๋‹จ์ˆœํžˆ ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ๊ธฐ ๋•Œ๋ฌธ์ž…๋‹ˆ๋‹ค.
08:30
and because we are primates
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๊ทธ๋ฆฌ๊ณ  ์˜์žฅ๋ฅ˜์ธ ์šฐ๋ฆฌ๋Š”
08:32
with many more neurons for a given body size
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๋‹ค๋ฅธ ๋™๋ฌผ๊ณผ ๋‹ฌ๋ฆฌ
08:34
than any other animal,
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์ฃผ์–ด์ง„ ์‹ ์ฒด ํฌ๊ธฐ์— ๋น„ํ•ด ํ›จ์”ฌ ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์กŒ๊ธฐ ๋•Œ๋ฌธ์—
08:36
the relative cost of our brain is large,
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์šฐ๋ฆฌ ๋‡Œ์˜ ์ƒ๋Œ€์ ์ธ ์†Œ๋น„๊ฐ€ ํฐ ๊ฑฐ์˜ˆ์š”.
08:39
but just because we're primates, not because we're special.
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ํ•˜์ง€๋งŒ ์šฐ๋ฆฌ๊ฐ€ ์˜์žฅ๋ฅ˜๋ผ์„œ ๊ทธ๋Ÿฐ ๊ฑฐ์ง€ ์šฐ๋ฆฌ๊ฐ€ ํŠน๋ณ„ํ•ด์„œ๋Š” ์•„๋‹ˆ์—์š”.
08:42
Last question, then:
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๊ทธ๋ ‡๋‹ค๋ฉด ๋งˆ์ง€๋ง‰ ์งˆ๋ฌธ์ž…๋‹ˆ๋‹ค.
08:44
how did we come by this remarkable number of neurons,
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์šฐ๋ฆฌ๋Š” ์–ด์ฉŒ๋‹ค ์ด๋ ‡๊ฒŒ ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง€๊ฒŒ ๋˜์—ˆ์„๊นŒ์š”.
08:47
and in particular, if great apes
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ํŠนํžˆ ์œ ์ธ์›์ด
08:49
are larger than we are,
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์šฐ๋ฆฌ๋ณด๋‹ค ํฌ๋‹ค๋ฉด
08:50
why don't they have a larger brain than we do, with more neurons?
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์™œ ๊ทธ๋“ค์€ ์šฐ๋ฆฌ๋ณด๋‹ค ๋” ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ์™€ ๋” ํฐ ๋‡Œ๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ์ง€ ์•Š์„๊นŒ์š”?
08:54
When we realized how much expensive it is
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์šฐ๋ฆฌ๊ฐ€ ๋‡Œ ์†์— ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ๋Š” ๊ฒŒ
08:56
to have a lot of neurons in the brain, I figured,
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์–ผ๋งˆ๋‚˜ ๋งŽ์€ ์—๋„ˆ์ง€๋ฅผ ํ•„์š”๋กœ ํ•˜๋Š”์ง€ ๊นจ๋‹ฌ์•˜์„ ๋•Œ
08:58
maybe there's a simple reason.
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์ „ ์•„๋งˆ ๊ฐ„๋‹จํ•œ ์ด์œ ๊ฐ€ ์žˆ์„ ๊ฑฐ๋ผ ์ƒ๊ฐํ–ˆ์–ด์š”.
09:00
They just can't afford the energy
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์œ ์ธ์›์€ ์ปค๋‹ค๋ž€ ๋ชธ๊ณผ
09:02
for both a large body and a large number of neurons.
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๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๋ชจ๋‘ ์œ ์ง€ํ•  ์—๋„ˆ์ง€๋ฅผ ๊ฐ๋‹นํ•  ์ˆ˜ ์—†์Šต๋‹ˆ๋‹ค.
09:05
So we did the math.
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๊ทธ๋ž˜์„œ ์šฐ๋ฆฐ ๊ณ„์‚ฐ์„ ํ–ˆ์–ด์š”.
09:06
We calculated on the one hand
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ํ•œํŽธ์œผ๋กœ๋Š”
09:08
how much energy a primate gets per day
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์˜์žฅ๋ฅ˜๊ฐ€ ๋‚  ๊ฒƒ์„ ๋จน์œผ๋ฉด์„œ
09:10
from eating raw foods,
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์–ป๋Š” ํ•˜๋ฃจ ์—๋„ˆ์ง€์˜ ์–‘์„ ๊ณ„์‚ฐํ–ˆ๊ณ 
09:11
and on the other hand, how much energy
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๋‹ค๋ฅธ ํ•œํŽธ์œผ๋กœ๋Š” ํŠน์ •ํ•œ ํฌ๊ธฐ์˜ ๋ชธ์ด
09:13
a body of a certain size costs
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์–ผ๋งˆ๋‚˜ ๋งŽ์€ ์—๋„ˆ์ง€๋ฅผ ์†Œ๋น„ํ•˜๊ณ 
09:15
and how much energy a brain of a certain number of neurons costs,
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ํŠน์ • ์ˆ˜์˜ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง„ ๋‡Œ๊ฐ€ ์–ผ๋งˆ๋‚˜ ๋งŽ์€ ์—๋„ˆ์ง€๋ฅผ ์“ฐ๋Š”์ง€ ๊ณ„์‚ฐํ–ˆ์–ด์š”.
09:19
and we looked for the combinations
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๊ทธ๋ฆฌ๊ณ  ์˜์žฅ๋ฅ˜๊ฐ€ ์ง€๋‹ ์ˆ˜ ์žˆ๋Š”
09:20
of body size and number of brain neurons
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์‹ ์ฒด ํฌ๊ธฐ์™€ ๋‡Œ ์‹ ๊ฒฝ ์„ธํฌ ์ˆ˜์˜
09:22
that a primate could afford
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์กฐํ•ฉ์„ ์‚ดํŽด๋ดค์Šต๋‹ˆ๋‹ค.
09:24
if it ate a certain number of hours per day.
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ํ•˜๋ฃจ์— ํŠน์ • ์‹œ๊ฐ„ ๋™์•ˆ ๋จน๋Š”๋‹ค๋Š” ๊ฐ€์ •ํ•˜์—์š”.
09:26
And what we found is that
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๊ทธ๋ฆฌ๊ณ  ์šฐ๋ฆฌ๋Š”
09:28
because neurons are so expensive,
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์‹ ๊ฒฝ ์„ธํฌ๋Š” ์•„์ฃผ ๋งŽ์€ ์—๋„ˆ์ง€๋ฅผ ์†Œ๋น„ํ•˜๊ธฐ ๋•Œ๋ฌธ์—
09:30
there is a tradeoff between body size and number of neurons.
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์‹ ์ฒด ํฌ๊ธฐ์™€ ์‹ ๊ฒฝ ์„ธํฌ ์ˆ˜ ์‚ฌ์ด์— ์ผ์ข…์˜ ๊ฑฐ๋ž˜๊ฐ€ ์žˆ๋‹ค๋Š” ๊ฑธ ์•Œ์•„๋ƒˆ์–ด์š”.
09:33
So a primate that eats eight hours per day
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ํ•˜๋ฃจ์— 8์‹œ๊ฐ„ ๋™์•ˆ ๋จน๋Š” ์˜์žฅ๋ฅ˜๋Š”
09:36
can afford at most 53 billion neurons,
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์ตœ๋Œ€ 530์–ต ๊ฐœ์˜ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ๋‹นํ•  ์ˆ˜ ์žˆ์ง€๋งŒ
09:39
but then its body cannot be any bigger
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๊ทธ ์‹ ์ฒด๋Š”
09:41
than 25 kilos.
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25 ํ‚ฌ๋กœ๊ทธ๋žจ ์ด์ƒ ์ปค์งˆ ์ˆ˜ ์—†์Šต๋‹ˆ๋‹ค.
09:43
To weigh any more than that,
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๊ทธ๋ณด๋‹ค ๋” ์ปค์ง€๋ ค๋ฉด
09:45
it has to give up neurons.
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์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ํฌ๊ธฐํ•ด์•ผ ํ•ด์š”
09:46
So it's either a large body
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๊ทธ๋ž˜์„œ ์ปค๋‹ค๋ž€ ์‹ ์ฒด
09:49
or a large number of neurons.
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์•„๋‹ˆ๋ฉด ๋งŽ์€ ์ˆ˜์˜ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง€๋Š” ๊ฒƒ์ด์ฃ .
09:50
When you eat like a primate,
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์˜์žฅ๋ฅ˜์ฒ˜๋Ÿผ ๋จน์œผ๋ฉด
09:52
you can't afford both.
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๋‘˜ ๋‹ค ๊ฐ๋‹นํ•  ์ˆ˜ ์—†์–ด์š”.
09:54
One way out of this metabolic limitation
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์ด๋Ÿฌํ•œ ์‹ ์ง„๋Œ€์‚ฌ์˜ ์ œ์•ฝ์—์„œ ๋ฒ—์–ด๋‚˜๋Š” ํ•œ๊ฐ€์ง€ ๋ฐฉ๋ฒ•์€
09:56
would be to spend even more hours per day eating,
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๋‚ ๋งˆ๋‹ค ๋จน๋Š” ์‹œ๊ฐ„์„ ๋Š˜๋ฆฌ๋Š” ๊ฒƒ์ด์ง€๋งŒ
09:59
but that gets dangerous,
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์ด ๋ฐฉ๋ฒ•์€ ์œ„ํ—˜ํ•˜๊ณ 
10:01
and past a certain point, it's just not possible.
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ํŠน์ •ํ•œ ์‹œ์ ์ด ์ง€๋‚˜๋ฉด ๋ถˆ๊ฐ€๋Šฅํ•ด์ง‘๋‹ˆ๋‹ค.
10:04
Gorillas and orangutans, for instance,
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์˜ˆ๋ฅผ ๋“ค์–ด ๊ณ ๋ฆด๋ผ์™€ ์˜ค๋ž‘์šฐํƒ„์€
10:05
afford about 30 billion neurons
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ํ•˜๋ฃจ์— 8์‹œ๊ฐ„ ๋ฐ˜ ๋™์•ˆ ๋จน์œผ๋ฉด์„œ
10:07
by spending eight and a half hours per day eating,
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300์–ต ๊ฐœ์˜ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ๋‹นํ•  ์ˆ˜ ์žˆ์–ด์š”.
10:10
and that seems to be about as much as they can do.
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๊ทธ๊ฒŒ ๊ทธ๋“ค์ด ๊ฐ๋‹นํ•  ์ˆ˜ ์žˆ๋Š” ์ตœ๋Œ€์น˜๋กœ ๋ณด์ž…๋‹ˆ๋‹ค.
10:13
Nine hours of feeding per day
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ํ•˜๋ฃจ 9์‹œ๊ฐ„์˜ ์Œ์‹ ์„ญ์ทจ๊ฐ€
10:15
seems to be the practical limit for a primate.
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์˜์žฅ๋ฅ˜์˜ ์‹ค์งˆ์ ์ธ ํ•œ๊ณ„์น˜๋กœ ๋ณด์ž…๋‹ˆ๋‹ค.
10:18
What about us?
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์šฐ๋ฆฌ๋Š” ์–ด๋–จ๊นŒ์š”?
10:20
With our 86 billion neurons
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860์–ต ๊ฐœ์˜ ์‹ ๊ฒฝ ์„ธํฌ์™€
10:21
and 60 to 70 kilos of body mass,
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60 ~ 70 ํ‚ฌ๋กœ์˜ ์‹ ์ฒด๋ฅผ ๊ฐ€์ง„
10:25
we should have to spend over nine hours
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์šฐ๋ฆฌ๋Š” ํ•˜๋ฃจ์—
10:28
per day every single day feeding,
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9์‹œ๊ฐ„ ์ด์ƒ์„ ๋จน์–ด์•ผ ํ•˜๋Š”๋ฐ
10:32
which is just not feasible.
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๊ทธ๋ ‡๊ฒŒ ํ•˜๋Š” ๊ฑด ๋ถˆ๊ฐ€๋Šฅํ•ด์š”.
10:34
If we ate like a primate,
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์šฐ๋ฆฌ๊ฐ€ ์˜์žฅ๋ฅ˜์ฒ˜๋Ÿผ ๋จน์—ˆ๋‹ค๋ฉด
10:36
we should not be here.
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์šฐ๋ฆฌ๋Š” ์—ฌ๊ธฐ์— ์—†์—ˆ์„ ๊ฒ๋‹ˆ๋‹ค.
10:38
How did we get here, then?
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๊ทธ๋ ‡๋‹ค๋ฉด ์šฐ๋ฆฐ ์–ด๋–ป๊ฒŒ ์ด ์ž๋ฆฌ์— ์žˆ๊ฒŒ ๋˜์—ˆ์„๊นŒ์š”?
10:40
Well, if our brain costs just as much energy
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์šฐ๋ฆฌ ๋‡Œ๊ฐ€ ํ•„์š”ํ•œ ๋งŒํผ
10:43
as it should, and if we can't spend
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๋งŽ์€ ์—๋„ˆ์ง€๋ฅผ ์†Œ๋น„ํ•˜๊ณ 
10:44
every waking hour of the day feeding,
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์šฐ๋ฆฌ๊ฐ€ ๊นจ์–ด์žˆ๋Š” ๋งค์‹œ๊ฐ„์„ ๋จน์œผ๋ฉฐ ๋ณด๋‚ผ ์ˆ˜ ์—†๋‹ค๋ฉด
10:48
then the only alternative, really,
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์˜ค์ง ํ•œ๊ฐ€์ง€ ์‹ค์ œ์ ์ธ ๋Œ€์•ˆ์€
10:50
is to somehow get more energy
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๊ฐ™์€ ์Œ์‹์—์„œ
10:52
out of the same foods.
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๋” ๋งŽ์€ ์—๋„ˆ์ง€๋ฅผ ์–ป๋Š” ๊ฒƒ์ž…๋‹ˆ๋‹ค.
10:54
And remarkably, that matches exactly
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๊ทธ๋ฆฌ๊ณ  ๋†€๋ž๊ฒŒ๋„ ์ด ๋ฐฉ๋ฒ•์€
10:58
what our ancestors are believed to have invented
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150๋งŒ ๋…„ ์ „ ์šฐ๋ฆฌ์˜ ์กฐ์ƒ๋“ค์ด
11:01
one and a half million years ago,
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๋ฐœ๋ช…ํ•œ ๊ฒƒ๊ณผ ์ผ์น˜ํ•ฉ๋‹ˆ๋‹ค.
11:03
when they invented cooking.
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์š”๋ฆฌ๋ฅผ ๋ฐœ๋ช…ํ•œ ์‹œ์ ์ด์ฃ .
11:05
To cook is to use fire
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์š”๋ฆฌ๋ผ๋Š” ๊ฑด ๋ถˆ์„ ์‚ฌ์šฉํ•ด
11:07
to pre-digest foods outside of your body.
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์Œ์‹์˜ ์†Œํ™”๊ฐ€ ์ž˜ ๋˜๋„๋ก ๋ชธ ๋ฐ–์—์„œ ์กฐ๋ฆฌํ•˜๋Š” ๊ฒ๋‹ˆ๋‹ค.
11:11
Cooked foods are softer, so they're easier to chew
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์š”๋ฆฌ๋œ ์Œ์‹์€ ๋” ๋ถ€๋“œ๋Ÿฌ์›Œ์„œ ๋” ์‰ฝ๊ฒŒ ์”นํžˆ๊ณ 
11:14
and to turn completely into mush in your mouth,
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์ž… ์•ˆ์—์„œ ์™„์ „ํžˆ ์ฃฝ์œผ๋กœ ๋ณ€ํ•ด
11:16
so that allows them to be completely digested
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์žฅ ๋‚ด์—์„œ ์™„๋ฒฝํ•œ ์†Œํ™”์™€
11:18
and absorbed in your gut,
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ํก์ˆ˜๋ฅผ ๊ฐ€๋Šฅํ•˜๊ฒŒ ํ•ด์š”.
11:20
which makes them yield much more energy in much less time.
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์งง์€ ์‹œ๊ฐ„ ์•ˆ์— ๋ณด๋‹ค ๋งŽ์€ ์—๋„ˆ์ง€๋ฅผ ์–ป๊ฒŒ ํ•˜๋Š” ๊ฑฐ์ฃ .
11:24
So cooking frees time for us to do
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๊ทธ๋ž˜์„œ ์š”๋ฆฌ๋Š” ์šฐ๋ฆฌ์—๊ฒŒ
11:26
much more interesting things with our day
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๋‚ ๋งˆ๋‹ค ํฅ๋ฏธ๋กœ์šด ์ผ์„ ํ•˜๊ณ 
11:28
and with our neurons
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์‹ ๊ฒฝ ์„ธํฌ์™€๋„ ํ•จ๊ป˜ ํ•  ์ˆ˜ ์žˆ๋Š” ์‹œ๊ฐ„์„ ์ค๋‹ˆ๋‹ค.
11:30
than just thinking about food,
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ํ•˜๋ฃจ ์ข…์ผ ๋‹จ์ˆœํžˆ ๋จน์„ ๊ฒƒ๋งŒ ์ƒ๊ฐํ•˜๊ณ 
11:31
looking for food, and gobbling down food
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๋จน์„ ๊ฒƒ์„ ์ฐพ์•„๋‹ค๋‹ˆ๊ณ 
11:33
all day long.
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๋จน๋Š” ๋Œ€์‹ ์—์š”.
11:34
So because of cooking, what once was
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์š”๋ฆฌ ๋•๋ถ„์—
11:37
a major liability, this large,
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ํ•œ ๋•Œ๋Š” ์ค‘๋Œ€ํ•œ ์ง์ด์—ˆ๋˜
11:39
dangerously expensive brain with a lot of neurons,
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์œ„ํ—˜ํ•  ์ •๋„๋กœ ๋งŽ์€ ์ˆ˜์˜ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ€์ง„ ํฐ ๋‡Œ๊ฐ€
11:42
could now become a major asset,
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์ง€๊ธˆ์€ ์ค‘์š”ํ•œ ์ž์‚ฐ์ด ๋˜์–ด
11:44
now that we could both afford the energy for a lot of neurons
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์ด์ œ ์šฐ๋ฆฐ ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ์œ ์ง€ํ•  ์—๋„ˆ์ง€๋ฅผ ์„ญ์ทจํ•  ์ˆ˜ ์žˆ๊ณ 
11:48
and the time to do interesting things with them.
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์‹ ๊ฒฝ ์„ธํฌ์™€ ๊ฐ™์ด ์žฌ๋ฏธ์žˆ๋Š” ์ผ์„ ํ•  ์‹œ๊ฐ„๋„ ๊ฐ€์งˆ ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค.
11:50
So I think this explains why the human brain
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๊ทธ๋ž˜์„œ ์ „ ์ด ์‚ฌ์‹ค์ด ์ธ๊ฐ„์˜ ๋‡Œ๊ฐ€
11:52
grew to become so large so fast in evolution,
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๋นจ๋ฆฌ ์ปค์ง€๋ฉฐ ์ง„ํ™”ํ•œ ์ด์œ ๋ฅผ ์„ค๋ช…ํ•  ์ˆ˜ ์žˆ๋‹ค๊ณ  ์ƒ๊ฐํ•ด์š”.
11:55
all of the while remaining just a primate brain.
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์—ฌ์ „ํžˆ ์˜์žฅ๋ฅ˜์˜ ๋‡Œ์ธ๋ฐ๋„ ๋ถˆ๊ตฌํ•˜๊ณ  ๋ง์ด์ฃ .
11:59
With this large brain now affordable by cooking,
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์š”๋ฆฌ๋กœ ์ธํ•ด ์ปค๋‹ค๋ž€ ๋‡Œ๋ฅผ ๊ฐ๋‹นํ•  ์ˆ˜ ์žˆ์–ด์„œ
12:02
we went rapidly from raw foods to culture,
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์šฐ๋ฆฌ๋Š” ๋‚ ์Œ์‹์—์„œ ๋ฌธํ™”,
12:05
agriculture, civilization, grocery stores,
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๋†์—…, ๋ฌธ๋ช…, ์‹๋ฃŒํ’ˆ ๊ฐ€๊ฒŒ,
12:07
electricity, refrigerators,
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์ „๊ธฐ, ๋ƒ‰์žฅ๊ณ ๋กœ ์žฌ๋นจ๋ฆฌ ์˜ฎ๊ฒจ๊ฐ”๊ณ 
12:09
all of those things that nowadays
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์š”์ฆ˜ ์ด ๋ชจ๋“  ๊ฒƒ๋“ค์€
12:11
allow us to get all the energy we need
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์—ฌ๋Ÿฌ๋ถ„์ด ์ข‹์•„ํ•˜๋Š” ํŒจ์ŠคํŠธํ‘ธ๋“œ ์‹๋‹น์—์„œ
12:13
for the whole day in a single sitting
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ํ•˜๋ฃจ์— ํ•„์š”ํ•œ ๋ชจ๋“  ์—๋„ˆ์ง€๋ฅผ
12:16
at your favorite fast food joint.
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ํ•œ ๋ฒˆ์— ์–ป์„ ์ˆ˜ ์žˆ๊ฒŒ ํ•ด์ค๋‹ˆ๋‹ค.
12:18
So what once was a solution
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ํ•œ ๋•Œ๋Š” ํ•ด๊ฒฐ์ฑ…์ด์—ˆ๋˜ ๊ฒƒ์ด
12:21
now became the problem,
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์ด์ œ๋Š” ๋ฌธ์ œ๊ฐ€ ๋˜์—ˆ๊ณ 
12:23
and ironically, we look for the solution in raw food.
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์•„์ด๋Ÿฌ๋‹ˆํ•˜๊ฒŒ๋„ ์šฐ๋ฆฐ ๊ทธ ํ•ด๋‹ต์„ ๋‚ ์Œ์‹์—์„œ ์ฐพ๊ณ  ์žˆ์–ด์š”.
12:28
So what is the human advantage?
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๊ทธ๋ ‡๋‹ค๋ฉด ์ธ๊ฐ„์ด ๊ฐ€์ง„ ์žฅ์ ์€ ๋ญ˜๊นŒ์š”?
12:31
What is it that we have
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๋Œ€์ฒด ๋‹ค๋ฅธ ๋™๋ฌผ์—๊ฒŒ๋Š” ์—†๋Š”
12:32
that no other animal has?
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๋ฌด์—‡์„ ์šฐ๋ฆฌ๊ฐ€ ๊ฐ€์ง€๊ณ  ์žˆ๋Š” ๊ฑธ๊นŒ์š”?
12:35
My answer is that we have the largest number
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์ œ ๋Œ€๋‹ต์€ ์šฐ๋ฆฐ ๋Œ€๋‡Œ ํ”ผ์งˆ์—
12:37
of neurons in the cerebral cortex,
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๊ฐ€์žฅ ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ ๊ฐ–๊ณ  ์žˆ๊ณ 
12:39
and I think that's the simplest explanation
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๊ทธ๊ฒƒ์ด ์šฐ๋ฆฌ์˜ ๋›ฐ์–ด๋‚œ ์ธ์ง€ ๋Šฅ๋ ฅ์— ๋Œ€ํ•œ
12:40
for our remarkable cognitive abilities.
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๊ฐ€์žฅ ๊ฐ„๋‹จํ•œ ์„ค๋ช…์ด๋ผ๊ณ  ์ƒ๊ฐํ•ฉ๋‹ˆ๋‹ค.
12:42
And what is it that we do that no other animal does,
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๋˜ํ•œ ์šฐ๋ฆฌ๋Š” ํ•˜์ง€๋งŒ ๋‹ค๋ฅธ ๋™๋ฌผ์€ ํ•˜์ง€ ์•Š๋Š”,
12:46
and which I believe was fundamental
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์ œ๊ฐ€ ๊ทธ๊ฒƒ์ด์•ผ๋ง๋กœ ์šฐ๋ฆฌ๊ฐ€
12:48
to allow us to reach that large,
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๋Œ€๋‡Œ ํ”ผ์งˆ ์†์— ๊ฐ€์žฅ ๋งŽ์€ ์‹ ๊ฒฝ ์„ธํฌ๋ฅผ
12:51
largest number of neurons in the cortex?
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๊ฐ€์งˆ ์ˆ˜ ์žˆ๊ฒŒ ํ•œ ๊ทผ์›์ด๋ผ๊ณ  ๋ฏฟ๋Š” ๊ฒƒ์€ ๋ญ˜๊นŒ์š”?.
12:53
In two words, we cook.
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๋‘ ๋‹จ์–ด๋กœ, ์šฐ๋ฆฌ๋Š” ์š”๋ฆฌํ•œ๋‹ค๋Š” ๊ฒ๋‹ˆ๋‹ค.
12:55
No other animal cooks its food. Only humans do.
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๋‹ค๋ฅธ ๋™๋ฌผ์€ ์š”๋ฆฌ๋ฅผ ํ•˜์ง€ ์•Š์•„์š”. ์‚ฌ๋žŒ๋“ค๋งŒ ์š”๋ฆฌ๋ฅผ ํ•˜์ฃ .
12:59
And I think that's how we got to become human.
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์ „ ๊ทธ๋กœ ์ธํ•ด ์šฐ๋ฆฌ๊ฐ€ ์ธ๊ฐ„์ด ๋˜์—ˆ๋‹ค๊ณ  ์ƒ๊ฐํ•ฉ๋‹ˆ๋‹ค.
13:02
Studying the human brain changed the way I think about food.
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์ธ๊ฐ„์˜ ๋‡Œ์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๋Š” ์ œ๊ฐ€ ์Œ์‹์„ ์ƒ๊ฐํ•˜๋Š” ๋ฐฉํ–ฅ์„ ๋ฐ”๊พธ์—ˆ์–ด์š”.
13:04
I now look at my kitchen,
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์ €๋Š” ์ด์ œ ๋ถ€์—Œ์„ ๋ณด๋ฉด์„œ
13:06
and I bow to it,
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์ธ์‚ฌ๋ฅผ ํ•˜๊ณ 
13:07
and I thank my ancestors for coming up
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์šฐ๋ฆฌ๋ฅผ ์ธ๊ฐ„์ด ๋˜๊ฒŒ ์ด๋ˆ
13:09
with the invention that probably made us humans.
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๋ฐœ๋ช…์„ ํ•˜์‹  ์กฐ์ƒ๋“ค๊ป˜ ๊ฐ์‚ฌ๋“œ๋ฆฝ๋‹ˆ๋‹ค.
13:11
Thank you very much.
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๊ฐ์‚ฌํ•ฉ๋‹ˆ๋‹ค.
13:13
(Applause)
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(๋ฐ•์ˆ˜)
์ด ์›น์‚ฌ์ดํŠธ ์ •๋ณด

์ด ์‚ฌ์ดํŠธ๋Š” ์˜์–ด ํ•™์Šต์— ์œ ์šฉํ•œ YouTube ๋™์˜์ƒ์„ ์†Œ๊ฐœํ•ฉ๋‹ˆ๋‹ค. ์ „ ์„ธ๊ณ„ ์ตœ๊ณ ์˜ ์„ ์ƒ๋‹˜๋“ค์ด ๊ฐ€๋ฅด์น˜๋Š” ์˜์–ด ์ˆ˜์—…์„ ๋ณด๊ฒŒ ๋  ๊ฒƒ์ž…๋‹ˆ๋‹ค. ๊ฐ ๋™์˜์ƒ ํŽ˜์ด์ง€์— ํ‘œ์‹œ๋˜๋Š” ์˜์–ด ์ž๋ง‰์„ ๋”๋ธ” ํด๋ฆญํ•˜๋ฉด ๊ทธ๊ณณ์—์„œ ๋™์˜์ƒ์ด ์žฌ์ƒ๋ฉ๋‹ˆ๋‹ค. ๋น„๋””์˜ค ์žฌ์ƒ์— ๋งž์ถฐ ์ž๋ง‰์ด ์Šคํฌ๋กค๋ฉ๋‹ˆ๋‹ค. ์˜๊ฒฌ์ด๋‚˜ ์š”์ฒญ์ด ์žˆ๋Š” ๊ฒฝ์šฐ ์ด ๋ฌธ์˜ ์–‘์‹์„ ์‚ฌ์šฉํ•˜์—ฌ ๋ฌธ์˜ํ•˜์‹ญ์‹œ์˜ค.

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