And we have problems like climate change because of these underlying trends as well.

If we had kept mortality rates where they were in 1920, we wouldn't have anywhere near the magnitude of the climate crisis we're facing now because there simply wouldn't have been enough people on the planet to emit enough carbon into the atmosphere to make a meaningful difference.

In a weird sense, climate change is the unintended consequence of industrialization and increased longevity.

So all this extra life is a mixed blessing, like any change this momentous.

But I want to stress not just that we did it, but I think the more interesting question is how we did it.

That's what's been obsessing me over the last years, that's the investigation I've been on, trying to figure out what are the prime movers when we see change this momentous.

What is really driving that change?

And I think we should say, given everything that's happening in the world, we should point out that, you know, one of those prime movers, which we should shout from the rooftops, is vaccines, right?

We doubled — Yes, right? Thank you.

I didn't invent vaccines, so I appreciate that.

I mean, for smallpox to polio, influenza, TB and measles, and covid.

I mean, if we celebrated the eradication of smallpox the way we celebrate the moon landing, we would have a lot less vaccine hesitancy in the world right now.

But I also think it's a mistake to focus exclusively on the march of science and the kind of tangible objects, like vaccines and antibiotics or X-rays.

And to explain what I mean by that, I think it's useful to look at the story of how we conquered one of the most terrifying threats of the 19th century.

Milk. Now, we think of milk as this kind of emblem of health and vitality, but in fact, in the middle of the 19th century, milk was a serious health threat, particularly to children.

We had no mechanical refrigeration and so there was a lot of spoilage problems.

People could get tuberculosis from milk.

They figured out this thing for urban cattle where they couldn't feed them grass so they would feed them slop from whiskey distilleries — instead of grass, brilliant idea — which produced this kind of blue-tinted milk that was very dangerous, called swill milk.

In 1850, more than half of all the deaths recorded in New York City were young children, many of them killed by contaminated milk.

And look, I know what you're thinking.

You're thinking, "I know how we solved this problem.

We solved it with science.

We solved it with chemistry." Right?

I mean, the solution is so famous.

It's sitting there printed on every carton of milk in every grocery store in the country, right?

Pasteurization.

But actually, the story of pasteurization is a case study in the limits of science because Louis Pasteur came up with his technique for sterilizing milk in 1865, but we didn't actually have pasteurized milk as a standard on American grocery stores' shelves until 1915, a full 50 years later.

And that's because science and chemistry on its own wasn't enough to make a meaningful change.

You also needed persuasion.

You had to convince people to drink pasteurized milk, you had to convince the dairy industry to make pasteurized milk, and that took a whole other cast of characters.

It took muckraking journalists.

It took crusading lawmakers.

There was a whole subculture of pasteurization activists back then.

Maybe the most unlikely one was a department store magnate named Nathan Straus, who got obsessed with the pasteurization cause and he funded all these milk depots all around New York City where pasteurized milk was sold at cost to low-income residents so that they would develop a taste for it.

So in a sense, the way to think about it is that Pasteur solved the problem on the level of chemistry, but Straus and his allies solved it on the level of society.

And you need both fronts to effect change on that scale.

And there's another prime mover that we don't talk about enough, which seems a little bit unlikely in the context of disruptive innovation, and that is large bureaucratic institutions.

Now, if that seems contradictory to you, I suggest that you flip through the pages of any pharmaceutical drug catalog from the early 20th century.

I mean, these things are just a laundry list of deadly poisons, one after another: arsenic, mercury, belladonna, not to mention all the heroin and cocaine.

A lot of medical historians believe that all-in pharmaceutical drugs were a net negative in terms of human health until the invention of antibiotics in the 1940s.

That's what life was like.