Hi, I'm John Green. This is Crash Course World History and today we're talking about one of my least favorite subjects, the end of humanity.
Mr. Green! Mr. Green! Does that mean that you can see the future? If so, how do things work out with Amanda Key?
Oh, me from the past, the phrase "work out" implies that there was a relationship to work out, which there wasn't, and there will never be.
However, you do currently know your eventual wife. But I'm not telling you who she is, because if I do you will screw it up!
[Theme Music]
So we're not gonna look at the actual end of humanity today. We're going to learn about a theory about the downfall of civilization.
And unlike all the true theories, this one doesn't involve aliens, or robots, or robot aliens.
But it is related to environmental catastrophes of the man-made variety. Today we're going to look at population and the most persistent theory about population growth and its effect on humanity.
The one proposed by Thomas Malthus.
And what's amazing about the persistence of this theory, is it's complete lack of connection to actual human history. All right so in 10,000 BCE fewer than a billion people lived on earth.
Nearly 12,000 years later, around 1800 CE, human population had grown to... still under a billion.
At about that time, an Anglican minister, named Thomas Malthus wrote an essay on the principle of population. That explained why this slow population growth was the way things were always going to be.
Malthus saw the growing number of poor people on the English streets and he did what any reasonable thinker would do, he analogized them to rabbits.
He reasoned that the same forces that checked the population of rabbits would limit humans too. Predators, harsh weather, epidemics, and starvation.
Now it turns out that humans have ways of dealing with predators, we killed all the lions. And also we've got this amazing way of dealing with harsh weather that rabbits have never figured out called clothes.
Not to even get in to fire and housing.
So that leaves us with alien predators, disease, and starvation as the big obstacles. Okay, we're going to address these one at a time.
First, Arnold Schwarzenegger already took care of the alien predators. Thank you Mr. Schwarzenegger, in exchange we made you Governor of California.
Then we have disease. So around the time Malthus was writing, disease was becoming less dangerous to human populations.
And then there's starvation, right, well we've argued in the past that starvation is generally a man-made problem. But to Malthus, it was still a natural disaster.
For Malthus, uncontrolled reproduction was the central problem. Remember, he was, you know, coming from the context of rabbits.
He explained it through math. Humans could reproduce geometrically, capable of doubling population every 25 years, but land on Earth is finite and at best, it could only be coaxed into producing small, arithmetic, increases in food.
So you've got population growing geometrically, food growing arithmetically, all the people are gonna die. Now among simpler creatures, the theory went food shortages caused immediate famine.
But humans would continue to eek out ever more desperate lives, as increasing demand raised the price of food, and clothing, and bread, and medicine.
Powerful individuals and nations would seize the assets of the weak, but even some of the strong would fall victim to hunger and disease.
Inevitably the population would then dip low enough for the land to recover. Giving another generation a chance to repeat the same mistakes.
Over time then, human population would remain roughly constant with the natural fertility of the land. Because he was such a fun guy, Malthus called this theory of history "The Cycle of Misery."
This essay is one of the most influential pieces of writing in history, along with a handful of other works, it established the methods and importance of the modern field of economics.
It opened the door to the universe of evolutionary science. And most immediately, Malthusian theory played a devastating role in the Irish Potato Famine of 1846-1851.
Let's go to the sure to be depressing, Thought Bubble.
Nearly 1 million Irish people died of starvation, disease, and violence during the famine, which was triggered when a fungus wiped out the one strain of potato grown in Ireland.
Had Ireland's poor population had access to the thousands of other varieties of potato or aid to purchase more expensive crops, the suffering may not have been as terrible.
But official English policy toward Ireland, as determined by its colonial master Charles Trevelyan, was to give no aid nor allow anyone else to give it either.
He blocked American ships filled with corn from reaching the island. He allowed Irish farms that grew crops other than potatoes to sell them straight to England.
Now hundreds of years of anti-Irish Catholic hatred, were the roots of England's cruel policies. But Malthusian theory also played a role.
In the century before 1846, Ireland's population had grown significantly, and many English thinkers saw the famine as an outcome of Malthus' predictions.
From this point of view, providing food or aid to the Irish was futile - it could only delay the cycle of misery until it's downward swings scythed down even more people.
Trevelyan thus felt assured of pronouncing that the only remedy for the starving was for them to die, and let their corpses serve to remind the survivors not to have sex. Quote,
"the judgment of God sent the calamity to teach the Irish a lesson and that calamity must not be too much mitigated".
Trevelyan reassured people upset about the news of starving children, the real evil with which we have to contend is not the physical evil of the famine,
but the moral evil of the selfish, perverse, and turbulent character of the people.
Thanks Thought Bubble. So why did Ireland want independence in the first place? Oh right, yeah that!
So by 1852, emigration and starvation had shrunk the population of Ireland from about 6.5 million to 4 million. In 2010, the islands population was still lower than at the famine's start.
So Malthusian theory seemed to have it's airtight proof, right?
Well, no.
In fact, even as Malthus was writing, the curve of human population growth was beginning to slope upward. The increase in population was so gradual that all Malthus noticed of it, were the outliers, the poor clinging to life.
But the growth in the number of human beings was far more permanent than Malthus ever imagined. In fact, it was unstoppable.
From 1750 to 1850, right when Malthus was alive, the number of humans on Earth grew by half a billion people. From about 800 million to 1.3 billion. By 1960, the population reached 3 billion.
And since then, the world has added a billion humans roughly every 15 years. Sometime in 2009 or 2010, the United Nations estimates that the Earth's 7 billionth person was born.
Consider that contrast, at the very moment that Malthus was writing that it was impossible, human population was beginning it's rocket like acceleration. So what did he miss?
Well, Malthus was like an A+ student in the subject of human existence, he was right for like 95% of history. But it turns out, grades aren't a super accurate predictor of success in life.
Malthus should have looked past prominent disasters like the potato famine and recognized that two major revolutions in food production were occurring while he was alive.
One of the reasons that he struck out so spectacularly is that, like many Western thinkers, he wasn't paying attention to China.
So Chinese farmers had altered the land, and used a number of inventions like dykes, and paddle wheels, and bicycle chains, to grow rice in man-made paddies.
It took a lot of labor, but it paid off. Especially when they discovered that by using the entrails and bones of the fish that swam in the water, they could get you know, fertilizer!
And then they could grow two rice crops in one year. Thus, the secret of China's greatness: food!
And with the benefit of added surplus, fortunate people in China were able to free up their time to study and to invent.
Yet, while the birth of this system had begun in the ancient past, additions to it continued throughout Chinese history and progressed straight through the Qing dynasty.
But agriculture was also changing in Europe during Malthus' lifetime. Like there's Jethro Tull's seed press, the crop rotation system developed by Charles "Turnip" Townsend,
and animal husbandry practiced by scientific farmers such as Robert Bakewell, who increased the size of his sheep by selective breeding.
So it kinda seems impossible that Malthus could have missed this revolution, because he could see it from his house in Surrey England.
But from his perspective, that agricultural revolution had the opposite effect of what had happened in China.
Like instead of giving people more food, and more comfort, it seemed to Malthus that it was driving them to greater misery.
That's because, for lots of Europeans the agricultural revolution was largely about evictions. The most important innovation of Europe's agricultural was largely invisible.
It was the decision to treat land as private property.
So for most Europeans, the concept that individual humans could own, like, land was a foreign concept. Even as late as 1500, most of Europe conceived of land as rightly belonging solely to its creator - God.
And then God's anointed on earth - kings and the Church - could parcel out packets of land to people they chose. But any land not specifically granted to a land lord, remained open to anyone who wanted to use it.
This open land was called the commons.
And in parts of Europe it made up more than half of the territory. But then around 1100 CE, British monarchs found themselves perpetually strapped for cash and they needed new taxes.
So in return for voting for tax increases and gifts, the crown granted enclosure acts to rich Englishman. Giving them the right to fence off the commons and claim it as their own.
So the people who'd used that land to graze animals, or cut wood, or grow crops could be forced off of it. And for the first time, richer people could maintain miles of fenced in property to pasture their sheep or dig mines.
Meanwhile the dispossessed, deprived of their opportunity to grow or hunt their own food, turned to beggary and theft, and to London.
Where they hired out their labor for wages. Wages?! That's not how humans should live! Having to fill out time cards and punch clocks!
Wait - Stan...don't you make wages?
Ugh, it's horrible. Myself, I live off the land. If I can't grow it, I won't eat it!
So by the time Malthus was a young man, things weren't great for the poor and dispossessed.
So it's a small wonder that Malthus only saw the downside of the agricultural revolution.
Only through historical hindsight, do we know that private property accelerated incentives to experiment with new methods of food production, which dramatically increased the amount of food produced.
Like before enclosure, it wouldn't have made sense for someone to buy a seed press and plant neat rows of seeds because anybody with a cow could have trampled on them an hour later.
The lower food prices created by more food supply began to ease the cycle of misery that Malthus described, although only just barely.
So in fact, agricultural innovations proved that Malthus was almost entirely wrong. So, why is he still influential? I think because there's a very seductive logic to the idea that resources, especially food, are finite.
I mean, we live on one planet that has a certain amount of arable land and surely at some point humans will suck up all of the resources. And this is especially true in the age of global climate change.
In 2014, the UN Intergovernmental Panel on Climate Change issued a report that warned of the potential for warmer temperatures to restrict food supplies in the face of growing demand.
In fact, it claimed that rising temperatures had already diminished wheat production by 2% per decade. While demand for food was rising at 14% over the same period. Food prices, which had been declining steadily until 2007, have been volatile since then.
Sometimes leading to famine other times to political unrest. And those are real problems that may yet prove disastrous.
But other doom and gloom scenarios regarding population and food, most notably the 1968 book The Population Bomb, have proven wrong at least so far.
In fact fewer people will die of starvation this year than died 500 years ago of starvation, even though we have far more people on Earth.
And there's still lots of room to improve agricultural yields.
But simply knowing that Malthus was wrong, isn't as interesting as thinking about why he was wrong. Malthus underestimated how successful we would be at adapting to environmental constraints.
And he underestimated the role that technology and innovation could play in creating a world where more humans could live. Now of course that hasn't come without its costs - including climate change.
And that's why I think Malthus remains so influential. Human existence is not a zero sum game. It is possible for me to benefit and other people also to benefit.
But it's also true that many resources that we imagine as infinite - aren't.
Thanks for watching. I'll see you next week.
Crash Course it filmed here in the Chad & Stacey Emigholz Studio in Indianapolis. And it's possible because of your support through subbable.com.
And also all of these people who make it.
Subbable's a voluntary subscription website that allows you to support Crash Course directly so we can keep it free for everyone forever. Thanks to all of our Subbable subscribers.
If you want to support Crash Course, you can also get like t-shirts, and posters, and DVDs. Okay!
Thank you again for watching. And as we say in my home town,
don't forget to be awesome.