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  • - [Sal] This timeline here covers 200,000 years,

  • from 200,000 years into the past, to the present.

  • And just to get a sense of the scale of this,

  • if we were to go 2,000 years ago

  • to the time of the Roman Empire,

  • that would be roughly here on the timeline.

  • If I were to say, when were the pyramids built?

  • That would be roughly there on the timeline.

  • So by human standards this is a very long period of time.

  • And I didn't choose this time span arbitrarily.

  • 200,000 years is about how long we believe

  • anatomically modern humans have been on our planet,

  • our sub-species of Homo sapiens sapiens.

  • Now the reason why I show these stone tools

  • is because the ages, the periods, of modern humanity,

  • or even pre-modern humanity,

  • are named after the types of tools

  • that have been found in archaeological digs.

  • So most of even pre-human, or near pre-human,

  • and human history,

  • has been the Paleolithic period, or old stone age.

  • Paleo, paleo for old,

  • lithic coming from lithos for stone.

  • So Paleolithic.

  • The old stone age is the great bulk of human history.

  • And there's also a Mesolithic

  • that comes about 15,000, 20,000 years ago.

  • But then around 10,000 years ago,

  • the stones have a much more polished appearance to them.

  • Things like this.

  • And so that period from about 10,000 years,

  • starting with about 10,000, 15,000 years,

  • depending on what part of the world you look at,

  • is referred to as the Neolithic period.

  • Neolithic,

  • referring to new stone.

  • And on top of this timeline,

  • I have also shown what's happening

  • at a very large scale, climactically,

  • on the Earth.

  • So these blue periods are ice ages,

  • and these reddish orange periods

  • are the periods in between ice ages.

  • And so you can see the last ice age ended

  • roughly 15,000 years ago,

  • and it began roughly 110,000 years ago.

  • Now I'm giving you all this context

  • about these Paleolithic, Neolithic, and the ice ages,

  • because we're gonna talk about probably

  • the most important series of events,

  • or innovation, in all of human history.

  • And that is agriculture.

  • Agriculture.

  • For most of human history,

  • over this Paleolithic period,

  • over most of this timeline

  • going up until about 10,000 or 15,000 years ago,

  • our ancestors were hunter gatherers.

  • They would have to chase the game wherever it might be,

  • they couldn't settle down in one place.

  • Maybe there were a few that were near

  • some sources of fish where they might be able to do

  • some basic fishing.

  • But they would have done hunting like this.

  • They would have done gathering,

  • which means getting berries or mushrooms

  • where they could find it.

  • It probably was eating a lot of things like insects,

  • and that is most of human history.

  • But then around 10,000 or 15,000 years ago,

  • we have the advent of human beings

  • taking nature into their own hands.

  • Instead of saying, let's just follow the game

  • wherever the game might migrate to,

  • let's actually domesticate these animals.

  • Let's take some of them, start breeding them

  • so they're more suitable for human consumption,

  • so that they are easier to raise, maybe more robust,

  • and we will breed them,

  • and we will raise them for milk, for meat.

  • We also started to domesticate plants.

  • Instead of saying, okay let's just gather

  • those berries there where it happens to emerge,

  • oh let's actually start to plant things.

  • And on a very predictable way, be able to harvest them,

  • and so be able to have a more predictable food supply.

  • Both of these things allowed human beings

  • to have a higher population density,

  • to start to settle down, to have a more sedentary life.

  • And this is a huge, huge, huge deal.

  • Just to get a sense.

  • We believe that the carrying capacity

  • for the planet,

  • for human beings as hunter gatherers,

  • is 10 million people.

  • And that is what we estimate the world population was

  • around the time of the last ice age, or shortly afterwards.

  • And that's because a tribe of 100 hunter gatherers

  • is going to need 50 square kilometers

  • to 100 square kilometers

  • to hunt and gather from,

  • or actually 500, from some of the estimates I've seen.

  • And it might seem like a lot of area

  • that you would need to hunt and gather from,

  • but imagine that you and your family

  • had to go live in the woods now.

  • How much food could you actually find?

  • You'd have to walk miles and miles per day,

  • if you're trying to hunt,

  • you'd have to walk miles and miles per day

  • to get whatever wild grains or berries, or whatever,

  • or mushrooms, or whatever, or insects,

  • that you might consume.

  • But then with the advent of agriculture

  • it allowed for a much, much higher density population.

  • In fact, going from the birth of agriculture,

  • which happens in the Neolithic period,

  • the dawn of agriculture coincides with the Neolithic period,

  • they're often used somewhat interchangeably.

  • Going from that period 10,000, 15,000 years ago,

  • to the time of ancient Rome,

  • so we're on the order of 10,000 years,

  • the world population with agriculture exploded

  • from 10 million to roughly 250 million.

  • And that's 25x.

  • And we know that from the time of Rome 'til now,

  • another 2,000 years with agriculture,

  • our population has gone up 28x,

  • it's growing exponentially, to seven billion.

  • And there's no way that we could have had

  • this level of density

  • without agriculture.

  • Now a key question is,

  • is why did agriculture emerge right then?

  • Well one theory is is, well it seems to be only,

  • and I'll say only in quotes,

  • only a few thousand years after the end of the ice age.

  • Maybe you had positive climate change,

  • at least from a human point of view,

  • that allowed land to support agriculture.

  • That seems like a reasonable theory.

  • Although you might say, well we've had other periods

  • where we didn't have an ice age,

  • how come we see no evidence of agriculture then?

  • And one counterargument or explanation I've heard for that

  • is, anatomically modern humans

  • started to emerge around 200,000 years ago,

  • but that doesn't mean that the way they thought,

  • or that their brains were the same as modern humans.

  • And so maybe in this period the human brain

  • just wasn't capable of performing,

  • or thinking of agriculture.

  • Other theories are is that the human population

  • through hunter gathering kept increasing over time,

  • and it was right after the last ice age

  • that you really got close to this

  • critical mass of population,

  • at which point, for every extra human to be born,

  • another human would not be able to live,

  • or not be able to be born,

  • because there was a fixed supply of food

  • as hunter gatherers.

  • And so you could say out of necessity,

  • maybe a tribe here or a little group there,

  • started to say hey, well what if we started to

  • domesticate some of this cattle?

  • Or if we started to plant crops?

  • All of a sudden they would start to have a higher density

  • and their population could increase.

  • And not only would they be able to survive,

  • but they could also be very dominant

  • in things like conflict.

  • Once you start having agriculture,

  • and as agriculture advances,

  • as I mentioned, these people could be more sedentary.

  • They wouldn't have to move around.

  • They wouldn't have to move around all of the time.

  • That allows them to

  • create even defensive structures.

  • You could have specialization,

  • where not everyone is having to worry about,

  • specialization,

  • not everyone is having to worry about food all of the time.

  • And so you could develop warriors,

  • you could have technology developing, especially weapons,

  • and so not only would that tribe or that group

  • be able to get higher density,

  • but they would be able to defend their property.

  • In fact they would probably care a lot more

  • about property,

  • because they use it to farm,

  • versus hunter gatherers

  • might just view that as their territory

  • that they wander over

  • in order to find food.

  • Now whatever the actual cause of the birth of agriculture,

  • it has had profound implications on our society.

  • You would not have had the birth of city-states,

  • without agriculture.

  • City-states had high density populations.

  • They could not have been supported with hunter gathering.

  • You could not have had the development of technology,

  • which, people needed more time,

  • you needed specialization, in order to have that.

  • It's, I would say, fair to say,

  • we wouldn't even have our modern,

  • our modern civilization would not have been possible

  • without agriculture.

  • I would not be making this video to you right now.

  • In fact most of us wouldn't even have been

  • around on the planet

  • because the planet wouldn't have been able to support

  • our really immensely large population

  • without not only agriculture, but an ever advancing,

  • technologically advancing agriculture.

  • So it might seem like a small thing.

  • You go from hunter gatherer to agriculture,

  • but it's been one of the most, maybe the most profound,

  • well it's probably up there with language and writing,

  • things that have defined

  • what makes humans humans.

  • And to get a sense of where this agriculture was born,

  • here's the various regions that we believe

  • agriculture emerged from.

  • The Levant right over here in the eastern Mediterranean,

  • modern day Middle East,

  • Syria, Israel, Palestine, Iraq,

  • southeastern Turkey,

  • this is one of the areas where we think

  • agriculture first emerged

  • on the order of 10,000 to 15,000 years ago.

  • We believe rice came from China.

  • I've seen estimates anywhere from 6,000 to 13,000 years ago.

  • You have the potato and other crops

  • coming from the Andes thousands of years ago,

  • and this is just a sample of the areas

  • where we see agriculture,

  • both domestication of crops and animals first emerging.

  • And what's interesting is,

  • over time we're likely to discover other places

  • as we have more archaeological digs

  • and we find more fossil evidence of

  • ancient agriculture and ancient peoples.

  • And even the time frame where we believe this happened,

  • the 10,000, 12,000, 15,000 years ago,

  • that's likely to maybe move back a little bit

  • as we discover older and older evidence.

  • So I'll leave you there,

  • but the big takeaway is

  • most of human history

  • we were not only making rough stones

  • for our weapons and our tools,