Origins of agriculture | World History | Khan Academy

This timeline here covers 200,000 years, from 200,000 years into the past to the present. 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.

I didn't choose this timespan arbitrarily; 200,000 years is about how long we believe anatomically modern humans have been on our planet, our subspecies of Homo sapiens sapiens.

Now, the reason why I show these stone tools is because the ages, the periods of modern humanity, or even premodern humanity, are named after the types of tools that have been found in archaeological digs. Most of even prehuman or near prehuman and human history has been the Paleolithic period, or Old Stone Age. "Paleo" means old, and "lithic" comes from "lithos," meaning stone. So, Paleolithic, the Old Stone Age, is the great bulk of human history.

There's also a Mesolithic that comes about 15,000 to 20,000 years ago, but then around 10,000 years ago, the stones have a much more polished appearance to them, like this. That period, starting with about 10,000 to 15,000 years ago, depending on what part of the world you look at, is referred to as the Neolithic period. "Neolithic" referring to New Stone.

On top of this timeline, I have also shown what's happening at a very large scale climactically on the Earth. The blue periods are ice ages, and these reddish-orange periods are the periods in between ice ages. You can see that the last ice age ended roughly 15,000 years ago and began roughly 110,000 years ago.

Now, I'm giving you all this context about these Paleolithic and Neolithic periods and the ice ages because we're going to talk about probably the most important series of events or innovations in all of human history. That is agriculture.

For most of human history, over this Paleolithic period, going up until about 10 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 them. They probably ate a lot of things like insects. That is most of human history.

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 it 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, easier to raise, maybe more robust. 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 where it happens to emerge," let's actually start to plant things. In a very predictable way, we can harvest them, having 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.

This is a 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. That is what we estimate the world population was at around the time of the last ice age or shortly afterward. A tribe of 100 hunter-gatherers was going to need 50 square kilometers to 100 square kilometers to hunt and gather from, or actually 500, which are some of the estimates I've seen.

It might seem like a lot of area that you would need to hunt and gather from, but imagine if you and your family had to go live in the woods. Now, how much food could you actually find? You would have to walk miles and miles per day if you're trying to hunt. You would have to walk miles and miles per day to get whatever wild grains or berries or mushrooms or insects that you might consume.

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—from that period, about 10,000 to 15,000 years ago, to the time of ancient Rome, we're talking on the order of 10,000 years.

The world population with agriculture exploded from 10 million to roughly 250 million, and that's a 25x increase. We know that from the time of Rome till now, another 2,000 years with agriculture, our population has gone up 28x; it's growing exponentially to 7 billion. There's no way that we could have had this level of density without agriculture.

Now a key question is, why did agriculture emerge right then? One theory is that it seems to be only, and I put "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, we've had other periods where we didn't have an ice age. How can we see no agriculture then? 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 their way of thinking or that their brains were the same as modern humans.

So maybe, in this period, the human brain just wasn't capable of performing or thinking of agriculture. Other theories are 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 that 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.

You could say, out of necessity, maybe a tribe here or a little group there started to say, "Hey, 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. Not only would they be able to survive, but they could also become very dominant in conflicts.

Once you start having agriculture, as I mentioned, these people could be more sedentary. 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 food all of the time, and so you could develop warriors. You could have technology developing, especially weapons.

Not only would that tribe or that group be able to get a 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 who might just view the territory as something they wander over 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 through hunter-gathering. You could not have had the development of technology, which needed more time and specialization in order to have that.

I would say it's fair to say we wouldn't even have our modern civilization without agriculture. I would not be making this video to you right now. In fact, most of us wouldn't have even been around on the planet because the planet wouldn't have been able to support our immensely large population without not only agriculture but an ever-advancing, technologically advancing agriculture.

So it might seem like a small thing to go from hunter-gathering 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.

To get a sense of where this agriculture was born, here are 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, with estimates ranging anywhere from 6,000 to 13,000 years ago.

You have the potato and other crops coming from the Andes thousands of years ago. This is just a sample of the areas where we see agriculture, both domestication of crops and animals, first emerging.

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. Even the timeframe where we believe this happened, the 10,000, 12,000, or 15,000 years ago, is 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 that most of human history, we were not only making rough stones for our weapons and our tools, but we were chasing animals wherever we could find them. We didn't have predictable food sources. We were gathering fruits, grains, and insects wherever we could to support our families, and there was a limit on how many humans could be around.

But shortly after the end of the Ice Age, it all changed. You had a population explosion, and we think that is due to agriculture.