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Welcome to rationally speaking, the podcast where we explore the borderlands between reason and nonsense.

I'm your host, Julia Galef, and I'm here with today's guest, economist Rick Nevin.

Rick is a senior economist at ICF International.

He's done research on a bunch of things, but maybe what he's most well known for is his research on the effects of lead exposure at a young

age. He's written a lot of papers on the topic, including, or in addition to a book titled

Lucifer Curves, the legacy of lead poisoning. That is what we're going to talk about today.

Rick, welcome to rationally speaking. Thank you. So first off, what Rick is the phenomenon that the lead

hypothesis was developed to explain? You know, what's the pattern in need of an explanation?

Well, there are several patterns, but probably one of people are most interested

in is crime. We experienced a long, seemingly relentless crime increase from the early 1960s

through the early 1990s in the U.S. And then we've seen a precipitous decline since then.

And it is well known that early childhood lead exposure affects brain development and lowers IQ,

but also affects the brain in many other ways that affect impulsivity and behavior.

And what I found, I started working on this in round 1994, is that if you look at the rise

...