The big question for this segment is, what is Threshold 7, and why is it important?

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Our seventh threshold of increasing complexity is linked

to the appearance of agriculture.

Why?

What is agriculture, and why is it such a big deal?

We've seen that our species appeared,

almost certainly in Africa, some time in the last 200,000 years.

Slowly, we start getting evidence that

our ancestors are displaying a quite exceptional creativity.

They start producing what looks like art, in paintings and sculptures.

We get hints of what looks like religion, and the tools they use

start getting more diverse, more precisely adapted, and more varied.

But for perhaps 95% of our history,

our ancestors lived off the land as foragers.

Living like foragers means that they got the resources that they needed

from their surroundings.

They gathered or hunted for food, for skins or

furs that could keep them warm, and for

materials with which to make shelters or to make gifts or ritual objects.

And if there wasn't enough, they moved on.

In fact, study of modern foraging societies suggests

that most foragers probably moved several times each year,

traveling around a familiar territory that they understood well.

Foraging could not support dense populations because it

simply didn't produce enough resources.

You couldn't have large villages or cities or empires.

Then, quite suddenly on big history time scales,

things begin to change in just the last 10,000 to 11,000 years.

To understand the crucial changes, it'll help to have a map in front of you.

Communities of farmers began to appear.

They appeared in the Fertile Crescent in the Middle East

from perhaps as early as 11,000 years ago.

Then, quite soon after, along the Nile River.

And then not long after that, along the Yellow River in China and

the Yangtze further south.

And in the highlands of Papua New Guinea from perhaps 9,000 to 7,000 years ago.

Then we start seeing them in parts of West Africa, in parts of Central America, and

in the Andes from about 5,000 years ago, and

in modern Pakistan from perhaps 4,000 years ago.

These communities were radically different.

They didn't just gather what they needed.

They began changing their surroundings.

They would divert streams and rivers.

They'd remove plants that got in their way.

But they'd look after those plants they liked, such as wheat or rice.

They'd get rid of animals they regarded as pests, and they'd look after and

protect those that they could use, such as goats or sheep or cattle.

Why did they bother?

Why did they work so hard at farming?

And why was farming so transformative?

Well, early farmers bothered because by farming, they got more energy and

resources than they could get by foraging.

In a given area, farmers could produce much more of what they needed.

They did so by manipulating the environment and

changing the mix of species so that there were more plants and

animals that they could use and less of those they couldn't use.

And that meant, in effect, that they were diverting more

of the energy that entered the biosphere through photosynthesis to their own use.

Now there's a puzzle here.

Why did so many communities start farming at roughly the same time,

within just a few thousand years?

We're still not quite sure, but two factors were clearly important.

First, by about 10,000 years ago, humans lived in every continent

apart from Antarctica, so there were no new continents to migrate to.

And in some regions such as in the narrow corridor from Egypt into Mesopotamia,

populations were getting quite crowded by the standards of foragers.

The fact that there were no new areas to migrate to

increased pressure to produce more food and resources.

Now second, at about the same time, the last Ice Age ended, and

this brought warm climates to many parts of the world.

In some regions, such as the Fertile Crescent in the Middle East, plants and

animals flourished so much that local communities of foragers found they

could harvest enough while staying in one place.

In these regions that archeologists sometimes call Gardens of Eden,

foragers began to settle down, but that turned out to be a trap.

Once communities had settled down, they become sedentary, their populations

began to grow faster because children no longer needed to be carried.

Suddenly, they found they had to produce more food.

They had to start weeding to protect valued plants.

They had to water those plants.

They had to protect them from predators.

In short, they had to start farming.

The impact of agriculture was huge.

That's why it counts as a sort of gear shift in human history.

Agriculture speeded up human history, and it launched an entire cascade of changes.

With more energy and

more resources, human populations began to grow in all the regions with agriculture.

But even more importantly, farming communities got denser and less nomadic.

With agriculture, you could support many more people from the same area.

Large villages appeared, and then eventually small towns,

and eventually cities that got their food and

other resources from surrounding villages and townships.

Humans also began to live in denser and

more complex communities, and this transformed how they lived.

Think about it.

If you live with just one family, everyone more or less knows the rules, and

everyone knows everyone else.

But live with 1,000 or 2,000 or 10,000 people, and you need new rules.

You need rules to say who controls what, who's in charge, who has what duties.

With more resources, people also started specializing.

In Mesopotamia, archaeologists can trace the slow appearance of specialists,

such as specialist potters.

Until by about 5,000 years ago,

we know that some potters were living entirely from pottery.

They were not farming any longer.

That meant that they had to be exchanging what they produced for food and

clothing and other goods with people who were farming.

So now we're beginning to get a division of labor and some form of markets.

Specialists of many kinds begin to appear, priests, soldiers, metal workers,

tanners, and eventually, specialists in writing and in ruling.

With larger and more diverse populations, the accumulation

of information through collective learning also began to speed up.

There were now more people with more information.

So we begin to see more innovation in technology.

For example, we see new methods of making objects from metals, from copper,

from bronze, and from perhaps 3,000 or 3,500 years ago, from iron.

We begin to see new forms of carts and chariots.

And we see new and much larger buildings.

We also see new forms of religion emerging.

And we see new social and political structures

as early forms of bureaucracy appear, and new forms of law making.

Now, we see similar changes in all of the core areas of agriculture,

and these changes take us to agrarian civilizations and the first states.

Settlements grew to form large villages, towns, and eventually cities.

Already by 6,000 years ago, most humans may have lived not as foragers but

in villages of farmers.

Then the first states appeared, probably in Egypt or

Mesopotamia between about 6,000 and 5,000 years ago.

Rulers appeared, who were surrounded with great prestige, who built

large monuments and large buildings, and who controlled entire cities.

They and their governments were supported by large populations of farmers who

produced most of the resources they needed.

There were markets that often linked the cities and governments and

states to other states.

They also had armies, and they collected taxes.

In short, everything appeared that we associate with agrarian civilizations.

Human history was launched on a new course.

And when writing appeared, which it did in all agrarian civilizations,

we get for the first time access to records of what was happening.

Writing is immensely important

because now we have an entirely new form of evidence with which to study the past.

And in fact, history as a discipline is often thought of

as the discipline that studies the past using writing.

But I hope you're beginning to understand in this course that we can also study

the past using many other forms of evidence.

Let's recapitulate Threshold 7.

With agricultural villages and agrarian civilizations,

we have human communities that are much larger, much more diverse,

and much more complex than the societies that existed before.

Now, what energy flow supported that complexity?

Well, I hope you understand by now that agriculture itself

generated entirely new energy flows.

It gave humans access to more energy and more resources

as they diverted more of the energy of photosynthesis to their own use.

What were the Goldilocks conditions for this threshold?

Well, two seem to have been crucial.

The first is the end of the last Ice Age, warmer climates

that allowed more abundance that allowed foragers to settle down.

But the second is the fact that humans, by 10,000 years ago,

seem to have filled up all of the Earth.

They had to start intensifying.

And finally, what emerged?

Well, what emerged with agriculture is human societies that were more diverse,

that were larger, that exchanged more ideas, and that had more dynamism.

So with agriculture, we begin to see a sort of speed up in the pace of change,

and an increase in the speed with which humans begin to control the biosphere.

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BIG HISTORY FRAMEWORK: David Christian - Why is Threshold 7 important?

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