Hello, we've been talking
about the agriculture
revolution,
arguably the most
significant transition
in all of human history.
I'd like to think
a little bit more
about that with you today
by considering two
questions in particular.
Firstly, why do big historians
make this argument
that this transition to farming
is so important?
All right.
Why does agriculture
matter so much?
And secondly, how do we
explain this transition?
Why would humans abandon
a life way that had
worked so well for so long,
for a quarter
of a million years,
for something
that was a lot riskier,
at least early on?
So the first question,
why does it matter?
Let's go back to the situation,
say, 12,000 years
ago in the Paleolithic.
We've seen that humans have
migrated all over the planet,
that they're all
pursuing foraging life ways.
These looked different depending
on the different environments
that people are living in,
but essentially
it's the same way
of making a living.
Humans are living
in small communities
because foragers have to keep
their population small.
So collective
learning is going on,
but on a pretty low level.
So change seemed somewhat slow,
almost imperceptible
to us today.
But then something changes.
Farming technologies
begin to appear
in different parts
of the planet.
And this quite quickly gives
humans access to more resources,
our populations increase,
population densities
in particular increase,
so villages appear
for the first time.
Some of these become large towns
and then enormous cities
with millions of residents.
So collective learning
begins to happen
at a much faster pace
and much larger scale.
And this means we get more
technological dynamism,
greater population growth.
This means that those
regions that adopt farming
get a sort of head start
on those regions that don't.
And when the world
zones later reconnect,
those farming
regions, if you like,
quite quickly come to dominate
those parts of the world
that never adopted farming
or adopted farming quite late.
So the adoption of
agriculture helps explain
so much of what
happened in world history
and really to explain
the geopolitical situation
on the planet to this very day.
The second question concerns
how we explain this,
and theorists have pondered this
for about 50 or 60 years now.
The most obvious answer would be
that somebody invented farming,
somebody just got sick
of wandering the landscaping,
being nomadic and foraging
and hunting and said,
"Why don't we just
stay in one place
and start to domesticate
plants and animals."
Now, this idea
makes a lot of sense,
it's very intuitive,
but it doesn't really work
because, you know, that farming
appeared independently
in a number of regions
around the world that were
completely isolated
from each other.
There's no possible way
that farmers in the Americas,
for example,
could have copied this idea
from farmers in Afro-Eurasia
because the Americas
were completely
sealed off by this stage.
We also know that not
everybody wanted to be a farmer.
We're aware of many
hunter gatherer groups
who lived in areas
where farming was going on
but quite clearly made the
decision not to adopt farming
because it appeared
a lot more hard work
and a lot more stressful.
So that argument
just doesn't work.
Instead, we explain farming
through a series of five steps
in which human intentional
decision-making
actually played
a very small role.
The first of these steps
was that humans were already
pre-adapted to make this
transition.
Our ancestors had survived
for an enormous amount of time
through living with nature.
They understood how
animals and plants worked.
They understood which plants
had a regular breeding cycle,
which animals were docile and
could be herded and so on.
The second step is that
a number of species
were also pre-adapted
to make this transition.
If you think about
the 200,000 or so
higher plants on the planet,
as biologists identify them,
only a hundred
or so of these plants have
proven themselves
suitable for domestication.
You could name some
of them, of course:
wheats and corns and rice
and vegetables and fruits
and nuts and so on.
Furthermore, of the 148
or so species of land mammals,
only about 14 have proven
themselves pre-adapted,
if you like, or suitable
for domestication.
Again, cattle, sheep, goats,
pigs, you could
name some of these.
The third step is that
in certain parts of the world,
humans were becoming
more sedentary.
They were abandoning
nomadic life ways
and settling down
in regions of local abundance.
At the end of the last Ice Age
as the ice sheets retreated
and warmer weather
conditions appeared,
it became possible for foragers
to stay in one place.
They weren't farming, of course.
They were still foraging
and hunting and gathering,
but they were able to settle in
these regions of local abundance
such as the Biblical
Gardens of Eden, which appeared
in the sort of Fertile Crescent
of Southwest Asia.
Now, the minute people stayed
in one place,
populations began to increase.
You might remember that hunter
gatherers had to keep
natural controls
on their populations
to sustain themselves
in these small communities.
The minute we stay in one place,
we no longer have to practice
infanticide or senilicide,
that is,
killing off unwanted babies
or unwanted older folks.
So populations begin to increase
and this builds population
pressure on these communities.
Many of these regions
where farming appears
are also natural
funnels for migration.
So you've got
these twin problems
of increasingly
large populations,
more and more people coming in.
It becomes impossible
to sustain yourselves
through hunter gathering.
These humans had become
trapped in the fourth step,
the trap of sedentism.
Inadvertently by choosing
to stay in one place,
they've trapped themselves
through increasing
population pressure
into having to find
some new way of survival,
and this leads directly to the
only option, which is farming.
Now, this five-step model works
everywhere on Earth
where farming appears,
certainly in the Fertile
Crescent of Southwest Asia,
along the Nile Valley in Egypt,
along the Huang He and
Yangtze River Valleys in China,
the Indus Valley
in Pakistan today,
Mesoamerica,
North America, South America.
It appears to be the model
that explains this
extraordinary transition
that sets human history
spiraling along a whole new
course of more dramatic change,
intensive population growth,
more and more
technological innovation.
The agriculture revolution
drives humans along a path
that leads directly
to the complexity
of the modern world.
