TEDGlobal 2013
Suzana Herculano-Houzel: What is so special about the human brain?
Suzana Herkulano-Hauzel (Suzana Herculano-Houzel): Zašto je ljudski mozak toliko poseban?
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Ljudski mozak je zagonetan - neobično veliki, uzimajući u obzir veličinu našeg tela, koristi ogromnu količinu energije za svoju težinu i ima bizarno gust cerebralni korteks. Ali zašto?
Neurolog Suzana Herkulano-Hauzel stavlja svoju detektivsku značku i vodi nas kroz ovu misteriju. Praveći "moždanu supu", ona dolazi do iznenađujućeg zaključka.
Suzana Herculano-Houzel - Neuroscientist
Suzana Herculano-Houzel shrunk the human brain by 14 billion neurons -- by developing a new way to count them. Full bio
Suzana Herculano-Houzel shrunk the human brain by 14 billion neurons -- by developing a new way to count them. Full bio
Double-click the English transcript below to play the video.
00:12
What is so special about the human brain?
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Zašto je toliko poseban ljudski mozak?
00:15
Why is it that we study other animals
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Zašto mi proučavamo druge životinje,
00:17
instead of them studying us?
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umesto da one proučavaju nas?
00:19
What does a human brain have or do
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Šta to ljudski mozak ima ili radi
00:21
that no other brain does?
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što nijedan drugi mozak ne može?
00:23
When I became interested
in these questions about 10 years ago,
in these questions about 10 years ago,
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Kada sam počela da se zanimam za ova
pitanja pre desetak godina,
pitanja pre desetak godina,
00:26
scientists thought they knew
what different brains were made of.
what different brains were made of.
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naučnici su mislili da znaju kakvog su
sastava različiti mozgovi.
sastava različiti mozgovi.
00:28
Though it was based on very little evidence,
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Iako je, u osnovi, bilo malo dokaza
00:30
many scientists thought that all mammalian brains,
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mnogi naučnici su mislili
da su mozgovi sisara,
da su mozgovi sisara,
00:32
including the human brain,
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uključujući i ljudski mozak,
00:34
were made in the same way,
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potpuno isto načinjeni,
00:35
with a number of neurons that was always
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sa brojem neurona
koji je oduvek
koji je oduvek
00:37
proportional to the size of the brain.
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bio proporcionalan
veličini mozga.
veličini mozga.
00:39
This means that two brains of the same size,
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To znači da dva mozga
istih veličina,
istih veličina,
00:41
like these two, with a respectable 400 grams,
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kao ova dva, od pristojnih
400 grama,
400 grama,
00:45
should have similar numbers of neurons.
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treba da imaju isti broj neurona.
00:47
Now, if neurons are the functional
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Sada, ako su neuroni funkcionalne
00:49
information processing units of the brain,
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prenosne jedinice informacija,
00:52
then the owners of these two brains
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onda vlasnici ova dva mozga
00:54
should have similar cognitive abilities.
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treba da imaju iste
kognitivne sposobnosti.
kognitivne sposobnosti.
00:56
And yet, one is a chimp,
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A ipak, jedan vlasnik je šimpanza,
00:59
and the other is a cow.
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a drugi vlasnik je krava.
01:01
Now maybe cows have a really rich
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Sada, možda krave imaju
jako bogat
jako bogat
01:04
internal mental life and are so smart
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unutrašnji, duševni život i
toliko su pametne
toliko su pametne
01:06
that they choose not to let us realize it,
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da su odlučile da nam ne dozvole
da to shvatimo,
da to shvatimo,
01:10
but we eat them.
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ali mi njih jedemo.
01:11
I think most people will agree
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Mislim da bi se većina
ljudi složila
ljudi složila
01:13
that chimps are capable of much more complex,
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da su šimpanze sposobne
za mnogo složenije,
za mnogo složenije,
01:15
elaborate and flexible behaviors than cows are.
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detaljnije i prilagodljivije
ponašanje nego krave.
ponašanje nego krave.
01:18
So this is a first indication that the
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Tako da je ovo prvi pokazatelj
01:20
"all brains are made the same way" scenario
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da scenario tipa:
"Svi mozgovi su isto načinjeni",
"Svi mozgovi su isto načinjeni",
01:22
is not quite right.
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nije baš prihvatljiv.
01:24
But let's play along.
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Ali, hajde da i mi
pretpostavimo isto.
pretpostavimo isto.
01:25
If all brains were made the same way
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Ako su svi mozgovi načinjeni isto,
01:27
and you were to compare animals
with brains of different sizes,
with brains of different sizes,
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i na vama je da poredite životinje
sa različitom veličinom mozga,
sa različitom veličinom mozga,
01:30
larger brains should always have more neurons
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veći mozgovi bi uvek trebalo
da imaju više neurona
da imaju više neurona
01:32
than smaller brains,
and the larger the brain,
and the larger the brain,
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od manjih i što je mozak veći,
01:34
the more cognitively able its owner should be.
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veće bi trebale da budu i kognitivne
sposobnosti njegovog vlasnika.
sposobnosti njegovog vlasnika.
01:37
So the largest brain around should also be
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Tako da najveći mozak treba da bude
01:39
the most cognitively able.
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i najviše kognitivno sposoban.
01:42
And here comes the bad news:
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Ali, evo loših vesti.
01:43
Our brain, not the largest one around.
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Naš mozak nije najveći
u okruženju.
u okruženju.
01:46
It seems quite vexing.
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Zvuči prilično uznemirujuće.
01:47
Our brain weighs between 1.2 and 1.5 kilos,
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Naš mozak je težine između
1,2 i 1,5 kilograma,
1,2 i 1,5 kilograma,
01:50
but elephant brains weigh between four and five kilos,
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ali mozak slona je težine
od četiri do pet kilograma,
od četiri do pet kilograma,
01:54
and whale brains can weigh up to nine kilos,
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a mozak kita može biti
težine i do 9 kilograma,
težine i do 9 kilograma,
01:56
which is why scientists used to resort to saying
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i zato su naučnici imali običaj
da pribegavaju tvrdnji,
da pribegavaju tvrdnji,
02:01
that our brain must be special
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da naši mozgovi mora
da su posebni,
da su posebni,
02:03
to explain our cognitive abilities.
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jer to objašnjava naše
kognitivne sposobnosti.
kognitivne sposobnosti.
02:06
It must be really extraordinary,
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Mora da je zaista izvanredan,
02:09
an exception to the rule.
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izuzetak od pravila.
02:11
Theirs may be bigger, but ours is better,
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Njihov je možda veći,
ali naš je bolji,
ali naš je bolji,
02:14
and it could be better, for example,
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i može biti bolji,
na primer,
na primer,
02:16
in that it seems larger than it should be,
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u tome, jer je veći nego
što treba da bude,
što treba da bude,
02:18
with a much larger cerebral cortex
than we should have
than we should have
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sa mnogo većim cerebralnim
korteksom nego što bi trebalo,
korteksom nego što bi trebalo,
02:21
for the size of our bodies.
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u odnosu na veličinu našeg tela.
02:22
So that would give us extra cortex
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Tako da nam ostaje višak korteksa
02:24
to do more interesting things
than just operating the body.
than just operating the body.
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za neke interesantnije stvari
od samog funkcionisanja tela.
od samog funkcionisanja tela.
02:27
That's because the size of the brain
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Veličina mozga
02:29
usually follows the size of the body.
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obično je srazmerna veličini tela.
02:31
So the main reason for saying that
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Tako da glavni razlog što kažemo
02:33
our brain is larger than it should be
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da je naš mozak veći
nego što bi trebalo
nego što bi trebalo
02:35
actually comes from comparing ourselves
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u stvari dolazi iz poređenja ljudi
02:37
to great apes.
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sa velikim majmunima.
02:39
Gorillas can be two to three times larger than we are,
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Gorile mogu biti dva ili tri puta
veće nego što smo mi,
veće nego što smo mi,
02:41
so their brains should also be larger than ours,
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tako da bi njihovi mozgovi trebalo
isto tako da budu veći od naših,
isto tako da budu veći od naših,
02:44
but instead it's the other way around.
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ali u stvari je obrnuto.
02:46
Our brain is three times larger than a gorilla brain.
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Naš mozak je tri puta veći
od mozga gorile.
od mozga gorile.
02:49
The human brain also seems special
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Ljudski mozak se isto tako čini poseban,
02:51
in the amount of energy that it uses.
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i u količini energije koju koristi.
02:53
Although it weighs only two percent of the body,
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Iako je težine samo dva procenta
od ukupne težine tela,
od ukupne težine tela,
02:56
it alone uses 25 percent of all the energy
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koristi 25 procenata ukupne energije
02:59
that your body requires to run per day.
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koju vaše telo zahteva da
bi funkcionisalo u jednom danu.
bi funkcionisalo u jednom danu.
03:02
That's 500 calories out of a total of 2,000 calories,
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To je 500 kalorija
od ukupnih 2000 kalorija,
od ukupnih 2000 kalorija,
03:05
just to keep your brain working.
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samo da bi mozak
bio u aktivnom stanju.
bio u aktivnom stanju.
03:07
So the human brain is larger than it should be,
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Znači, ljudski mozak je veći
nego što bi trebalo da bude,
nego što bi trebalo da bude,
03:10
it uses much more energy than it should,
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koristi mnogo više energije
nego što je potrebno -
nego što je potrebno -
03:12
so it's special.
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znači da je poseban.
03:14
And this is where the story started to bother me.
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I evo gde je priča počela da mi smeta.
03:16
In biology, we look for rules
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U biologiji, mi tražimo pravila
03:18
that apply to all animals and to life in general,
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koja primenjujemo na životinje
i život uopšte,
i život uopšte,
03:21
so why should the rules of evolution
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i zašto se onda pravila evolucije
03:23
apply to everybody else but not to us?
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primenjuju na sve ostale,
ali ne i na nas?
ali ne i na nas?
03:26
Maybe the problem was with the basic assumption
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Možda je problem bio
u osnovnoj pretpostavci
u osnovnoj pretpostavci
03:29
that all brains are made in the same way.
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da su svi mozgovi istog sastava.
03:30
Maybe two brains of a similar size
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Možda, dva mozga istih veličina,
03:32
can actually be made of
very different numbers of neurons.
very different numbers of neurons.
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u stvari, mogu biti sastavljeni od
različitog broja neurona.
različitog broja neurona.
03:35
Maybe a very large brain
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Možda, veoma veliki mozak
03:36
does not necessarily have more neurons
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nema i veći broj neurona
03:38
than a more modest-sized brain.
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od manjeg mozga.
03:40
Maybe the human brain
actually has the most neurons
actually has the most neurons
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Možda ljudski mozak u stvari
ima najviše neurona
ima najviše neurona
03:43
of any brain, regardless of its size,
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od bilo kog mozga,
nezavisno od veličine,
nezavisno od veličine,
03:46
especially in the cerebral cortex.
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posebno u cerebralnom korteksu.
03:48
So this to me became
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Tako da je ovo postalo za mene
03:50
the important question to answer:
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važno pitanje na koje treba
da dam odgovor:
da dam odgovor:
03:51
how many neurons does the human brain have,
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koliko neurona ljudski mozak ima,
03:54
and how does that compare to other animals?
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i kako se to može porediti
sa drugim životinjama?
sa drugim životinjama?
03:56
Now, you may have heard or read somewhere
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Možda ste čuli ili pročitali negde
03:59
that we have 100 billion neurons,
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da mi imamo 100 milijardi neurona,
04:01
so 10 years ago, I asked my colleagues
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i pre 10 godina, pitala sam
svoje kolege
svoje kolege
04:03
if they knew where this number came from.
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da li možda znaju otkud
ova brojka.
ova brojka.
04:05
But nobody did.
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Ali niko nije znao.
04:06
I've been digging through the literature
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Malo sam kopala po literaturi
04:08
for the original reference for that number,
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tražeći originalnu referencu za tu brojku,
04:10
and I could never find it.
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i nikada je nisam mogla pronaći.
04:11
It seems that nobody had actually ever counted
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Izgleda da niko nije, u stvari,
nikada izbrojao
nikada izbrojao
04:14
the number of neurons in the human brain,
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broj neurona u ljudskom mozgu,
04:16
or in any other brain for that matter.
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ili bilo kom drugom mozgu.
04:18
So I came up with my own way
to count cells in the brain,
to count cells in the brain,
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Tako da sam pronašla sopstveni način
da izbrojim ćelije u mozgu,
da izbrojim ćelije u mozgu,
04:22
and it essentially consists of
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i u osnovi, sastoji se u
04:24
dissolving that brain into soup.
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rastvaranju mozga u supu.
04:27
It works like this:
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To ovako funkcioniše:
04:29
You take a brain, or parts of that brain,
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mozak, ili delove mozga,
04:32
and you dissolve it in detergent,
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rastvorite u deterdžentu,
04:34
which destroys the cell membranes
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koji uništava ćelijske membrane
04:35
but keeps the cell nuclei intact,
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ali ćelijska jezgra ostaju netaknuta,
04:38
so you end up with a suspension of free nuclei
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i na kraju završite sa
suspenzijom slobodnih jezgara
suspenzijom slobodnih jezgara
04:41
that looks like this,
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koja izgleda ovako,
04:43
like a clear soup.
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kao bistra supa.
04:44
This soup contains all the nuclei
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Ova supa sadrži sva jezgra
04:46
that once were a mouse brain.
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koja su nekada bila u mozgu miša.
04:48
Now, the beauty of a soup is that because it is soup,
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Sada, prednosti supe su te
04:51
you can agitate it and make those nuclei
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da je možete promućkati i naterati jezgra
04:54
be distributed homogeneously in the liquid,
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da se pravilno rasporede u tečnosti,
04:56
so that now by looking under the microscope
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tako da posmatranjem pod mikroskopom
04:58
at just four or five samples
of this homogeneous solution,
of this homogeneous solution,
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samo četiri ili pet uzoraka
ovog homogenog rastvora
ovog homogenog rastvora
05:02
you can count nuclei, and therefore tell
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možete da izbrojite jezgra,
a potom i kažete
a potom i kažete
05:05
how many cells that brain had.
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od koliko ćelija se mozak sastojao.
05:06
It's simple, it's straightforward,
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Jednostavno je i direktno,
05:08
and it's really fast.
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i veoma brzo.
05:09
So we've used that method to count neurons
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Tako da smo mi koristili tu metodu
da izbrojimo neurone
da izbrojimo neurone
05:11
in dozens of different species so far,
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različitih vrsta,
05:14
and it turns out that all brains
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i ispostavlja se da nisu svi mozgovi
05:15
are not made the same way.
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istog sastava.
05:18
Take rodents and primates, for instance:
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Uzmite glodare i primate,
na primer.
na primer.
05:20
In larger rodent brains, the average size
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U većim mozgovima glodara,
prosečna veličina
prosečna veličina
05:22
of the neuron increases,
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neurona raste,
05:24
so the brain inflates very rapidly
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tako da se mozak uvećava
veoma brzo
veoma brzo
05:27
and gains size much faster than it gains neurons.
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i uvećava se mnogo brže nego
što postiže veći broj neurona.
što postiže veći broj neurona.
05:30
But primate brains gain neurons
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Ali kod primata, mozak postiže
veći broj neurona
veći broj neurona
05:32
without the average neuron becoming any larger,
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bez uvećavanja samog neurona,
05:34
which is a very economical way
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što je prilično ekonomičan način
05:35
to add neurons to your brain.
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dodavanja neurona vašem mozgu.
05:37
The result is that a primate brain
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Kao rezultat, mozak primata
05:39
will always have more neurons than
a rodent brain of the same size,
a rodent brain of the same size,
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će uvek imati više neurona od
mozga glodara koji je iste veličine,
mozga glodara koji je iste veličine,
05:42
and the larger the brain,
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i što je mozak veći,
05:44
the larger this difference will be.
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veća će biti i razlika.
05:46
Well, what about our brain then?
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A, šta je onda sa
našim mozgovima?
našim mozgovima?
05:48
We found that we have, on average,
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Otkrili smo da mi u proseku imamo
05:50
86 billion neurons,
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86 milijardi neurona,
05:51
16 billion of which are in the cerebral cortex,
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16 milijardi su u cerebralnom korteksu,
05:54
and if you consider that the cerebral cortex
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i ako uzmete u obzir da je
cerebralni korteks
cerebralni korteks
05:56
is the seat of functions like
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glavni za funkcije,
kao što su:
kao što su:
06:00
awareness and logical and abstract reasoning,
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svesnost, logično i
apstraktno rezonovanje,
apstraktno rezonovanje,
06:03
and that 16 billion is the most neurons
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i da je 16 milijardi najveći
broj neurona
broj neurona
06:06
that any cortex has,
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koji bilo koji korteks sadrži,
06:08
I think this is the simplest explanation
156
356766
1718
mislim da je ovo najjednostavnije
objašnjenje
objašnjenje
06:10
for our remarkable cognitive abilities.
157
358484
3142
naših izvanrednih kognitivnih sposobnosti.
06:13
But just as important is what
the 86 billion neurons mean.
the 86 billion neurons mean.
158
361626
3221
Ali isto tako važno je, šta znači uopšte
broj od 86 milijardi neurona.
broj od 86 milijardi neurona.
06:16
Because we found that the relationship
159
364847
1529
Zato što smo pronašli
da veza između
da veza između
06:18
between the size of the brain
and its number of neurons
and its number of neurons
160
366376
2352
veličine mozga i broja neurona
06:20
could be described mathematically,
161
368728
1627
može biti matematički opisana,
06:22
we could calculate what a human brain
162
370355
2218
možemo pokazati kako bi ljudski mozak
06:24
would look like if it was made like a rodent brain.
163
372573
2674
izgledao da je po sastavu
kao mozak glodara.
kao mozak glodara.
06:27
So, a rodent brain with 86 billion neurons
164
375247
3574
Tako da bi mozak glodara
sa 86 milijardi neurona
sa 86 milijardi neurona
06:30
would weigh 36 kilos.
165
378821
3121
bio težine 36 kilograma.
06:33
That's not possible.
166
381942
1633
To nije moguće.
06:35
A brain that huge would be crushed
167
383575
1906
Toliki mozak bi bio uništen
06:37
by its own weight,
168
385481
1184
svojom težinom,
06:38
and this impossible brain would go
169
386665
1587
i takav mozak bi išao
06:40
in the body of 89 tons.
170
388252
3771
uz telo težine od 89 tona.
06:44
I don't think it looks like us.
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392023
2134
Mislim da to ne liči na nas.
06:46
So this brings us to a very important
conclusion already,
conclusion already,
172
394157
2553
Tako da nas ovo već dovodi
do važnog zaključka,
do važnog zaključka,
06:48
which is that we are not rodents.
173
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2647
koje glasi: mi nismo glodari.
06:51
The human brain is not a large rat brain.
174
399357
3268
Mozak ljudi nije veliki mozak pacova.
06:54
Compared to a rat, we might seem special, yes,
175
402625
2628
U poređenju sa pacovima,
mi možda izgledamo posebno,
mi možda izgledamo posebno,
06:57
but that's not a fair comparison to make,
176
405253
2220
ali to nije pravedno poređenje
06:59
given that we know that we are not rodents.
177
407473
2089
znajući da mi nismo glodari.
07:01
We are primates,
178
409562
1390
Mi smo primati,
07:02
so the correct comparison is to other primates.
179
410952
2774
tako da je pravilno poređenje ono
sa drugim primatima.
sa drugim primatima.
07:05
And there, if you do the math,
180
413726
1227
I tu, ako odradite matematiku,
07:06
you find that a generic primate
181
414953
2786
pronalazite da će primat
07:09
with 86 billion neurons
182
417739
1930
sa 86 milijardi neurona
07:11
would have a brain of about 1.2 kilos,
183
419669
3003
imati mozak težine oko
1,2 kilograma,
1,2 kilograma,
07:14
which seems just right,
184
422672
1889
što je i sasvim dovoljno,
07:16
in a body of some 66 kilos,
185
424561
1972
za nekoga ko je težine od
nekih 66 kilograma,
nekih 66 kilograma,
07:18
which in my case is exactly right,
186
426533
2645
što je u mom slučaju
potpuno tačno,
potpuno tačno,
07:21
which brings us to a very unsurprising
187
429178
2620
i to nas dovodi do veoma poznatog,
07:23
but still incredibly important conclusion:
188
431798
2969
ali ipak neverovatno
značajnog zaključka:
značajnog zaključka:
07:26
I am a primate.
189
434767
1341
Ja sam primat.
07:28
And all of you are primates.
190
436108
2698
I svi vi ste primati.
07:30
And so was Darwin.
191
438806
1900
Kao što je i Darvin bio.
07:32
I love to think that Darwin
would have really appreciated this.
would have really appreciated this.
192
440706
2940
Volim da mislim da bi Darvin
zaista cenio ovo.
zaista cenio ovo.
07:35
His brain, like ours,
193
443646
1967
Njegov mozak, kao i naš
07:37
was made in the image of other primate brains.
194
445613
3511
napravljen je po ugledu
na druge primate.
na druge primate.
07:41
So the human brain may be remarkable, yes,
195
449124
2302
Tako da ljudski mozak možda
jeste izvanredan, da,
jeste izvanredan, da,
07:43
but it is not special in its number of neurons.
196
451426
2781
ali nije poseban u pogledu
broja neurona.
broja neurona.
07:46
It is just a large primate brain.
197
454207
1855
Samo je to jedan veliki
mozak primata.
mozak primata.
07:48
I think that's a very humbling and sobering thought
198
456062
3044
Mislim da je to jedna veoma
skromna i trezvena misao,
skromna i trezvena misao,
07:51
that should remind us of our place in nature.
199
459106
3063
koja treba da nas podseti
koje je naše mesto u prirodi.
koje je naše mesto u prirodi.
07:54
Why does it cost so much energy, then?
200
462169
2644
Zašto je onda potrebno
utrošiti toliko energije?
utrošiti toliko energije?
07:56
Well, other people have figured out
201
464813
1447
Neki ljudi su pronašli
07:58
how much energy the human brain
202
466260
1503
koliko je energije potrebno
ljudskom mozgu
ljudskom mozgu
07:59
and that of other species costs,
203
467763
1407
i mozgu nekih drugih vrsta,
08:01
and now that we knew how many neurons
204
469170
1652
i sada kada znamo koliko neurona
08:02
each brain was made of, we could do the math.
205
470822
2342
svaki mozak ima, možemo
primeniti matematiku.
primeniti matematiku.
08:05
And it turns out that both human
206
473164
1866
Ispostavlja se da je
i za ljudske
i za ljudske
08:07
and other brains cost about the same,
207
475030
2823
i za mozgove drugih vrsta,
utrošak isti,
utrošak isti,
08:09
an average of six calories
per billion neurons per day.
per billion neurons per day.
208
477853
3421
prosečno šest kalorija na
milijardu neurona, dnevno.
milijardu neurona, dnevno.
08:13
So the total energetic cost of a brain
209
481274
2139
Tako da je ukupni,
energetski utrošak
energetski utrošak
08:15
is a simple, linear function
210
483413
2034
jednostavna, linearna funkcija
08:17
of its number of neurons,
211
485447
1709
broja neurona,
08:19
and it turns out that the human brain
212
487156
2183
i ispostavilo se da ljudski mozak
08:21
costs just as much energy as you would expect.
213
489339
3841
troši onoliko energije
koliko se i očekivalo.
koliko se i očekivalo.
08:25
So the reason why the human brain
214
493180
2091
Tako da je razlog zbog
kojeg ljudski mozak
kojeg ljudski mozak
08:27
costs so much energy is simply because
215
495271
1672
troši toliko energije,
jednostavan,
jednostavan,
08:28
it has a huge number of neurons,
216
496943
1983
jer ima veliki broj neurona,
08:30
and because we are primates
217
498926
1485
i zato što smo mi primati
08:32
with many more neurons for a given body size
218
500411
2499
sa mngo većim brojem neurona
u odnosu na veličinu tela
u odnosu na veličinu tela
08:34
than any other animal,
219
502910
1522
od bilo koje druge vrste,
08:36
the relative cost of our brain is large,
220
504432
3540
relativna potrošnja našeg
mozga je ogromna
mozga je ogromna
08:39
but just because we're primates,
not because we're special.
not because we're special.
221
507972
3001
ali samo zato jer smo mi primati,
ne zato što smo posebni.
ne zato što smo posebni.
08:42
Last question, then:
222
510973
1190
Poslednje pitanje, onda:
08:44
how did we come by this
remarkable number of neurons,
remarkable number of neurons,
223
512163
3115
kako smo se mi zadesili sa ovako
velikim brojem neurona,
velikim brojem neurona,
08:47
and in particular, if great apes
224
515278
1900
iako su veliki majmuni
08:49
are larger than we are,
225
517178
1555
veći od nas,
08:50
why don't they have a larger brain
than we do, with more neurons?
than we do, with more neurons?
226
518733
3765
zašto oni nemaju veći mozak,
sa više neurona?
sa više neurona?
08:54
When we realized how much expensive it is
227
522498
2090
Kada smo shvatili koliko je zahtevno
08:56
to have a lot of neurons in the brain, I figured,
228
524588
2333
imati puno neurona u mozgu,
08:58
maybe there's a simple reason.
229
526921
2003
možda je razlog jednostavan.
09:00
They just can't afford the energy
230
528924
1683
Oni ne mogu da priušte
dovoljno energije
dovoljno energije
09:02
for both a large body
and a large number of neurons.
and a large number of neurons.
231
530607
2950
i za ogromna tela i za
veliki broj neurona.
veliki broj neurona.
09:05
So we did the math.
232
533557
1429
Tako da smo
odradili matematiku.
odradili matematiku.
09:06
We calculated on the one hand
233
534986
1600
Izračunali smo, sa jedne strane,
09:08
how much energy a primate gets per day
234
536586
1941
koliko je energije potrebno
sisaru dnevno,
sisaru dnevno,
09:10
from eating raw foods,
235
538527
1350
ako se hrane sirovom hranom,
09:11
and on the other hand, how much energy
236
539877
2037
i sa druge strane, koliko energije
09:13
a body of a certain size costs
237
541914
1764
za telo određene veličine.
09:15
and how much energy a brain of a
certain number of neurons costs,
certain number of neurons costs,
238
543678
3387
i koliko je energije potrebno mozgu
koji ima određeni broj neurona,
koji ima određeni broj neurona,
09:19
and we looked for the combinations
239
547065
1489
i tragali smo za kombinacijom
09:20
of body size and number of brain neurons
240
548554
2411
veličine tela i broja neurona
09:22
that a primate could afford
241
550965
1270
koje primat sebi može priuštiti
09:24
if it ate a certain number of hours per day.
242
552235
2548
ako jede određen broj sati dnevno.
09:26
And what we found is that
243
554783
1816
I ono što smo pronašli je to
09:28
because neurons are so expensive,
244
556599
1712
da su neuroni veoma skupi.
09:30
there is a tradeoff between
body size and number of neurons.
body size and number of neurons.
245
558311
3370
Postoji kompromis između
veličine tela i broja neurona.
veličine tela i broja neurona.
09:33
So a primate that eats eight hours per day
246
561681
2951
Tako da primat koji jede
osam sati dnevno
osam sati dnevno
09:36
can afford at most 53 billion neurons,
247
564632
3024
može najviše priuštiti
53 milijarde neurona,
53 milijarde neurona,
09:39
but then its body cannot be any bigger
248
567656
1727
ali onda telo ne može postati teže
09:41
than 25 kilos.
249
569383
1954
od 25 kilograma.
09:43
To weigh any more than that,
250
571337
1701
Veća težina
09:45
it has to give up neurons.
251
573038
1769
znači i manji broj neurona.
09:46
So it's either a large body
252
574807
2653
Tako da ili je telo veće
09:49
or a large number of neurons.
253
577460
1495
ili je veći broj neurona.
09:50
When you eat like a primate,
254
578955
1365
Kada se hranite kao primati,
09:52
you can't afford both.
255
580320
2236
ne možete sebi priuštiti
i jedno i drugo.
i jedno i drugo.
09:54
One way out of this metabolic limitation
256
582556
1964
Jedini izlaz iz ovakvih postavljenih
metaboličkih granica
metaboličkih granica
09:56
would be to spend even more hours per day eating,
257
584520
3401
bi bio: još više sati utrošiti na ishranu,
09:59
but that gets dangerous,
258
587921
1363
ali to već postaje opasno,
10:01
and past a certain point, it's just not possible.
259
589284
2719
i posle određene granice,
nije ni moguće.
nije ni moguće.
10:04
Gorillas and orangutans, for instance,
260
592003
1537
Gorile i orangutani, na primer,
10:05
afford about 30 billion neurons
261
593540
1923
mogu priuštiti sebi
30 milijardi neurona,
30 milijardi neurona,
10:07
by spending eight and a half hours per day eating,
262
595463
2966
provodeći dnevno
8 i po sati u jelu,
8 i po sati u jelu,
10:10
and that seems to be about as much as they can do.
263
598429
3116
i to je izgleda i najviše što mogu.
10:13
Nine hours of feeding per day
264
601545
1791
Devet sati hranjenja dnevno,
10:15
seems to be the practical limit for a primate.
265
603336
3271
izgleda da je realna granica,
koja je postavljena za primate.
koja je postavljena za primate.
10:18
What about us?
266
606607
1791
Šta je sa nama?
10:20
With our 86 billion neurons
267
608398
1600
Sa naših 86 milijardi neurona
10:21
and 60 to 70 kilos of body mass,
268
609998
3035
i od 60 do 70 kilograma telesne mase,
10:25
we should have to spend over nine hours
269
613033
3561
trebalo bi da provodimo preko devet sati
10:28
per day every single day feeding,
270
616594
3575
svakog dana, hraneći se,
10:32
which is just not feasible.
271
620169
2039
što prosto, nije izvodljivo.
10:34
If we ate like a primate,
272
622208
1834
Da jedemo kao primati,
10:36
we should not be here.
273
624042
2253
ne bi trebalo da budemo ovde.
10:38
How did we get here, then?
274
626295
2127
Kako smo u stvari dospeli ovde, onda?
10:40
Well, if our brain costs just as much energy
275
628422
2735
Pa, ako našim mozgovima treba energije
10:43
as it should, and if we can't spend
276
631157
1723
koliko je potrebno, i ako
ne možemo da provedemo
ne možemo da provedemo
10:44
every waking hour of the day feeding,
277
632880
3674
svaki sat tokom dana, hraneći se
10:48
then the only alternative, really,
278
636554
1911
onda je jedina mogućnost, zaista
10:50
is to somehow get more energy
279
638465
1958
da nekako dobijemo više energije
10:52
out of the same foods.
280
640423
1953
iz iste hrane.
10:54
And remarkably, that matches exactly
281
642376
3800
I izvanredno, to se poklapa upravo
10:58
what our ancestors are believed to have invented
282
646176
3037
sa otkrićem naših predaka
11:01
one and a half million years ago,
283
649213
1839
pre milion i po godina,
11:03
when they invented cooking.
284
651052
2782
kada su i izumeli kuvanje.
11:05
To cook is to use fire
285
653834
1970
Kuvanje znači koristiti vatru
11:07
to pre-digest foods outside of your body.
286
655804
3800
da bi se hrana mogla bolje svariti.
11:11
Cooked foods are softer, so they're easier to chew
287
659604
2606
Kuvana hrana je mekša, tako da je
lakša da se žvaće
lakša da se žvaće
11:14
and to turn completely into mush in your mouth,
288
662210
2563
i potpuno se pretvara
u kašu u ustima,
u kašu u ustima,
11:16
so that allows them to be completely digested
289
664773
2152
tako da može biti potpuno svarena
11:18
and absorbed in your gut,
290
666925
1436
i apsorbovana u stomaku,
11:20
which makes them yield much more
energy in much less time.
energy in much less time.
291
668361
3655
što za kraće vreme donosi mnogo
više energije u mnogo kraćem vremenu.
više energije u mnogo kraćem vremenu.
11:24
So cooking frees time for us to do
292
672016
2489
Tako da kuvanje nama štedi
vreme da bismo radili
vreme da bismo radili
11:26
much more interesting things with our day
293
674505
2062
neke mnogo interesantnije
stvari u našem danu
stvari u našem danu
11:28
and with our neurons
294
676567
1480
i sa našim neuronima,
11:30
than just thinking about food,
295
678047
1905
da ne bismo samo razmišljali o hrani,
11:31
looking for food, and gobbling down food
296
679952
1704
tragali za hranom i gutali hranu
11:33
all day long.
297
681656
1225
po čitav dan.
11:34
So because of cooking, what once was
298
682881
2499
I tako, zbog kuvanja, ono što je
11:37
a major liability, this large,
299
685380
2353
nekada bila velika odgovornost,
ovako veliki
ovako veliki
11:39
dangerously expensive brain with a lot of neurons,
300
687733
3033
veoma skup mozak
sa puno neurona,
sa puno neurona,
11:42
could now become a major asset,
301
690766
2036
sada može postati naše glavno oruđe,
11:44
now that we could both afford
the energy for a lot of neurons
the energy for a lot of neurons
302
692802
3251
sad kada možemo priuštiti
i energiju za puno neurona
i energiju za puno neurona
11:48
and the time to do interesting things with them.
303
696056
2503
i vreme, da bismo uradili
zanimljive stvari sa njima.
zanimljive stvari sa njima.
11:50
So I think this explains why the human brain
304
698559
1974
Tako da ja mislim ovo objašnjava
zašto je ljudski mozak
zašto je ljudski mozak
11:52
grew to become so large so fast in evolution,
305
700533
3240
tako brzo postao razvijen
tokom evolucije,
tokom evolucije,
11:55
all of the while remaining just a primate brain.
306
703773
3897
a sve vreme ostajući
samo mozak primata.
samo mozak primata.
11:59
With this large brain now affordable by cooking,
307
707670
2774
Sa ovako velikim mozgom, kojeg možemo
i koristiti, zahvaljujući kuvanju,
i koristiti, zahvaljujući kuvanju,
12:02
we went rapidly from raw foods to culture,
308
710444
2913
munjevito smo prešli
sa sirove hrane na kulture,
sa sirove hrane na kulture,
12:05
agriculture, civilization, grocery stores,
309
713357
2606
poljoprivredu, civilizaciju, bakalnice,
12:07
electricity, refrigerators,
310
715963
1625
elektricitet, frižidere,
12:09
all of those things that nowadays
311
717588
1607
sve te stvari koje nam danas
12:11
allow us to get all the energy we need
312
719195
2042
omogućavaju da priuštimo
svu potrebnu energiju
svu potrebnu energiju
12:13
for the whole day in a single sitting
313
721237
2782
za ceo dan, samo u jednom obroku
12:16
at your favorite fast food joint.
314
724019
2954
u omiljenom lancu brze hrane.
12:18
So what once was a solution
315
726973
2437
Tako da, ono što je nekada bilo rešenje,
12:21
now became the problem,
316
729410
1699
sada postaje problem,
12:23
and ironically, we look for the solution in raw food.
317
731109
5517
i ironično, to rešenje tražimo
u sirovoj hrani.
u sirovoj hrani.
12:28
So what is the human advantage?
318
736626
2556
I šta je prednost ljudi?
12:31
What is it that we have
319
739182
1503
Šta je to što mi imamo,
12:32
that no other animal has?
320
740685
2535
a nijedna druga životinja nema?
12:35
My answer is that we have the largest number
321
743220
2348
Moj odgovor je da imamo najveći broj
12:37
of neurons in the cerebral cortex,
322
745568
1472
neurona u cerebralnom korteksu,
12:39
and I think that's the simplest explanation
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i mislim da je to
najjednostavnije objašnjenje
najjednostavnije objašnjenje
12:40
for our remarkable cognitive abilities.
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za naše izuzetne kognitivne sposobnosti.
12:42
And what is it that we do that no other animal does,
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A šta je ono što mi radimo,
a nijedna druga životinja ne radi
a nijedna druga životinja ne radi
12:46
and which I believe was fundamental
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i što mislim da je bilo fundamentalno
12:48
to allow us to reach that large,
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da bismo uopšte mogli
da dosegnemo taj veliki,
da dosegnemo taj veliki,
12:51
largest number of neurons in the cortex?
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najveći broj neurona
u moždanoj kori?
u moždanoj kori?
12:53
In two words, we cook.
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Dve reči: mi kuvamo.
12:55
No other animal cooks its food. Only humans do.
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Nijedna druga životinja ne kuva
svoju hranu. Samo ljudi to rade.
svoju hranu. Samo ljudi to rade.
12:59
And I think that's how we got to become human.
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I ja mislim da smo upravo tako mi
i postali ljudi.
i postali ljudi.
13:02
Studying the human brain changed
the way I think about food.
the way I think about food.
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Proučavanje ljudskog mozga je promenilo
način na koji razmišljam o hrani.
način na koji razmišljam o hrani.
13:04
I now look at my kitchen,
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Sada pogledam u svoju kuhinju
13:06
and I bow to it,
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i klanjam se,
13:07
and I thank my ancestors for coming up
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i zahvaljujem našim precima
što su nabasali
što su nabasali
13:09
with the invention that probably made us humans.
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na otkriće koje nas je verovatno
i načinilo ljudima.
i načinilo ljudima.
13:11
Thank you very much.
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Hvala vam mnogo.
13:13
(Applause)
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(Aplauz)
ABOUT THE SPEAKER
Suzana Herculano-Houzel - NeuroscientistSuzana Herculano-Houzel shrunk the human brain by 14 billion neurons -- by developing a new way to count them.
Why you should listen
How many neurons make a human brain? For years, the answer has been (give or take) 100 billion. But neuroscientist Suzana Herculano-Houzel decided to count them herself. Her research approach involved dissolving four human brains (donated to science) into a homogeneous mixture -- in her lab at the Institute of Biomedical Sciences in Rio de Janeiro, they call it "brain soup." She then took a sample of the mix, counted the number of cell nuclei belonging to neurons, and scaled that up. Result: the human brain has about 86 billion neurons, 14 billion fewer than assumed -- but intriguingly, far more than other animals, relative to brain size.
She suggests that it was the invention of cooking by our ancestors -- which makes food yield much more metabolic energy -- that allowed humans to develop the largest primate brain. She's now working on elephant and whale brains to test her hypothesis.
Suzana Herculano-Houzel | Speaker | TED.com