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!

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.

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