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- [Sal] This timeline
here covers 200,000 years,
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from 200,000 years into
the past, to the present.
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And just to get a sense
of the scale of this,
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if we were to go 2,000 years ago
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to the time of the Roman Empire,
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that would be roughly
here on the timeline.
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If I were to say, when
were the pyramids built?
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That would be roughly
there on the timeline.
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So by human standards this is
a very long period of time.
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And I didn't choose this
time span arbitrarily.
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200,000 years is about how long we believe
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anatomically modern humans
have been on our planet,
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our sub-species of Homo sapiens sapiens.
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Now the reason why I
show these stone tools
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is because the ages, the
periods, of modern humanity,
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or even pre-modern humanity,
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are named after the types of tools
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that have been found
in archaeological digs.
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So most of even pre-human,
or near pre-human,
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and human history,
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has been the Paleolithic
period, or old stone age.
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Paleo, paleo for old,
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lithic coming from lithos for stone.
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So Paleolithic.
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The old stone age is the
great bulk of human history.
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And there's also a Mesolithic
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that comes about 15,000, 20,000 years ago.
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But then around 10,000 years ago,
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the stones have a much more
polished appearance to them.
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Things like this.
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And so that period from
about 10,000 years,
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starting with about 10,000, 15,000 years,
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depending on what part
of the world you look at,
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is referred to as the Neolithic period.
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Neolithic,
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referring to new stone.
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And on top of this timeline,
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I have also shown what's happening
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at a very large scale, climactically,
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on the Earth.
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So these blue periods are ice ages,
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and these reddish orange periods
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are the periods in between ice ages.
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And so you can see the last ice age ended
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roughly 15,000 years ago,
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and it began roughly 110,000 years ago.
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Now I'm giving you all this context
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about these Paleolithic,
Neolithic, and the ice ages,
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because we're gonna talk about probably
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the most important series of events,
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or innovation, in all of human history.
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And that is agriculture.
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Agriculture.
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For most of human history,
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over this Paleolithic period,
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over most of this timeline
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going up until about
10,000 or 15,000 years ago,
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our ancestors were hunter gatherers.
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They would have to chase the
game wherever it might be,
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they couldn't settle down in one place.
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Maybe there were a few that were near
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some sources of fish where
they might be able to do
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some basic fishing.
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But they would have
done hunting like this.
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They would have done gathering,
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which means getting berries or mushrooms
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where they could find it.
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It probably was eating a
lot of things like insects,
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and that is most of human history.
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But then around 10,000
or 15,000 years ago,
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we have the advent of human beings
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taking nature into their own hands.
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Instead of saying, let's
just follow the game
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wherever the game might migrate to,
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let's actually domesticate these animals.
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Let's take some of them,
start breeding them
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so they're more suitable
for human consumption,
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so that they are easier to
raise, maybe more robust,
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and we will breed them,
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and we will raise them for milk, for meat.
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We also started to domesticate plants.
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Instead of saying, okay let's just gather
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those berries there where
it happens to emerge,
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oh let's actually start to plant things.
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And on a very predictable
way, be able to harvest them,
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and so be able to have a
more predictable food supply.
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Both of these things allowed human beings
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to have a higher population density,
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to start to settle down, to
have a more sedentary life.
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And this is a huge, huge, huge deal.
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Just to get a sense.
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We believe that the carrying capacity
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for the planet,
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for human beings as hunter gatherers,
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is 10 million people.
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And that is what we estimate
the world population was
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around the time of the last
ice age, or shortly afterwards.
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And that's because a tribe
of 100 hunter gatherers
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is going to need 50 square kilometers
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to 100 square kilometers
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to hunt and gather from,
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or actually 500, from some
of the estimates I've seen.
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And it might seem like a lot of area
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that you would need to
hunt and gather from,
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but imagine that you and your family
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had to go live in the woods now.
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How much food could you actually find?
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You'd have to walk
miles and miles per day,
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if you're trying to hunt,
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you'd have to walk miles and miles per day
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to get whatever wild grains
or berries, or whatever,
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or mushrooms, or whatever, or insects,
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that you might consume.
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But then with the advent of agriculture
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it allowed for a much, much
higher density population.
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In fact, going from the
birth of agriculture,
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which happens in the Neolithic period,
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the dawn of agriculture coincides
with the Neolithic period,
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they're often used
somewhat interchangeably.
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Going from that period
10,000, 15,000 years ago,
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to the time of ancient Rome,
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so we're on the order of 10,000 years,
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the world population
with agriculture exploded
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from 10 million to roughly 250 million.
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And that's 25x.
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And we know that from the
time of Rome 'til now,
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another 2,000 years with agriculture,
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our population has gone up 28x,
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it's growing exponentially,
to seven billion.
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And there's no way that we could have had
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this level of density
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without agriculture.
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Now a key question is,
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is why did agriculture emerge right then?
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Well one theory is is,
well it seems to be only,
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and I'll say only in quotes,
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only a few thousand years
after the end of the ice age.
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Maybe you had positive climate change,
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at least from a human point of view,
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that allowed land to support agriculture.
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That seems like a reasonable theory.
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Although you might say,
well we've had other periods
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where we didn't have an ice age,
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how come we see no evidence
of agriculture then?
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And one counterargument or
explanation I've heard for that
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is, anatomically modern humans
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started to emerge around
200,000 years ago,
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but that doesn't mean
that the way they thought,
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or that their brains were
the same as modern humans.
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And so maybe in this
period the human brain
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just wasn't capable of performing,
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or thinking of agriculture.
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Other theories are is
that the human population
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through hunter gathering
kept increasing over time,
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and it was right after the last ice age
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that you really got close to this
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critical mass of population,
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at which point, for every
extra human to be born,
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another human would not be able to live,
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or not be able to be born,
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because there was a fixed supply of food
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as hunter gatherers.
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And so you could say out of necessity,
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maybe a tribe here or
a little group there,
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started to say hey, well
what if we started to
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domesticate some of this cattle?
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Or if we started to plant crops?
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All of a sudden they would
start to have a higher density
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and their population could increase.
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And not only would they
be able to survive,
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but they could also be very dominant
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in things like conflict.
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Once you start having agriculture,
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and as agriculture advances,
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as I mentioned, these people
could be more sedentary.
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They wouldn't have to move around.
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They wouldn't have to move
around all of the time.
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That allows them to
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create even defensive structures.
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You could have specialization,
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where not everyone is
having to worry about,
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specialization,
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not everyone is having to worry
about food all of the time.
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And so you could develop warriors,
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you could have technology
developing, especially weapons,
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and so not only would
that tribe or that group
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be able to get higher density,
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but they would be able
to defend their property.
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In fact they would
probably care a lot more
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about property,
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because they use it to farm,
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versus hunter gatherers
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might just view that as their territory
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that they wander over
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in order to find food.
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Now whatever the actual cause
of the birth of agriculture,
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it has had profound
implications on our society.
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You would not have had
the birth of city-states,
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without agriculture.
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City-states had high density populations.
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They could not have been
supported with hunter gathering.
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You could not have had the
development of technology,
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which, people needed more time,
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you needed specialization,
in order to have that.
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It's, I would say, fair to say,
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we wouldn't even have our modern,
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our modern civilization
would not have been possible
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without agriculture.
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I would not be making this
video to you right now.
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In fact most of us wouldn't even have been
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around on the planet
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because the planet wouldn't
have been able to support
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our really immensely large population
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without not only agriculture,
but an ever advancing,
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technologically advancing agriculture.
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So it might seem like a small thing.
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You go from hunter
gatherer to agriculture,
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but it's been one of the
most, maybe the most profound,
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well it's probably up there
with language and writing,
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things that have defined
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what makes humans humans.
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And to get a sense of where
this agriculture was born,
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here's the various regions that we believe
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agriculture emerged from.
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The Levant right over here
in the eastern Mediterranean,
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modern day Middle East,
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Syria, Israel, Palestine, Iraq,
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southeastern Turkey,
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this is one of the areas where we think
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agriculture first emerged
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on the order of 10,000
to 15,000 years ago.
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We believe rice came from China.
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I've seen estimates anywhere
from 6,000 to 13,000 years ago.
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You have the potato and other crops
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coming from the Andes
thousands of years ago,
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and this is just a sample of the areas
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where we see agriculture,
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both domestication of crops
and animals first emerging.
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And what's interesting is,
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over time we're likely
to discover other places
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as we have more archaeological digs
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and we find more fossil evidence of
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ancient agriculture and ancient peoples.
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And even the time frame where
we believe this happened,
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the 10,000, 12,000, 15,000 years ago,
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that's likely to maybe
move back a little bit
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as we discover older and older evidence.
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So I'll leave you there,
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but the big takeaway is
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most of human history
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we were not only making rough stones
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for our weapons and our tools,
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but we were chasing animals
wherever we could find 'em.
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We didn't have predictable food sources.
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We were gathering fruits and grains,
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and insects wherever we could
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to support our families,
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and there was a limit on how
many humans could be around.
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But shortly after the end of
the ice age, it all changed.
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You had a population explosion,
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and we think that is due to agriculture.