Stephan Heblich

There's a story of microevolutionary biology, which is about the peppered moth.

I'm not sure if you've ever heard about this.

The peppered moth appears in the UK in two varieties, a darker and lighter variety.

And it's well known that before industrialization in the north of England, the lighter variety was the predominant species.

And this was basically because it could hide on trees from predators.

But then as cold smoke started turning trees darker, we see a rise in the instance of this darker version of the peppered moth.

In cities in the Western Hemisphere, winds blow from the west to the east.

And you might observe that in a lot of these cities, east sides are more deprived.

We started wondering if this was driven by coal smoke during industrialization and a sorting of poor people into the East Side and rich people away from the East Side.

And we wanted to understand if this has long-lasting effects.

We started looking into historical maps and found out that Victorian cartographers were absolutely stunning in the level of detail that they drew into their maps.

We found the exact location of industrial smokestacks within factory buildings.

We basically found across all these 70 cities.

In England, we found about 5,000 chimney locations, like the exact geolocations.

They were literally like a historical version of Google Maps.

So after coal smoke came in, we see a resorting of poor households into the east side.

We have data from 1817, which is before coal smoke was a main fuel for industrialization.

And we find that in 1817, the wind direction where coal smoke would blow to doesn't have an effect.

We had a census where we had all the names and addresses transcribed.

And because there was by now a lot of coal being burned.