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Comment by micromacrofoot | Hacker News Reader

From what I've read the removal of lead from gasoline is partially a factor in the sudden reduction of crime during the latter half of the 20th century, but it's not enough to explain the entire trend... which seems to be a preponderance of factors.

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People say this about lead, people say this about abortion, people say this about building more prisons and 3-strike laws.

Nothing is monocausal, don't trust anyone who makes such a claim unless they provide extraordinary evidence.

Obviously nothing is monocausal, but it seems like the link with lead here is best supported by evidence among the things you've listed. It holds constant across several countries and cultures where those other factors are quite different. Western Europe wasn't throwing up prisons and enacting 3-strike laws, but saw similar declines in crime. You can find similar counter examples around abortion access as well. Those thing probably contribute, but the effect size of removing lead from the environments seem really large!

The lead hypothesis is supported by particularly strong evidence: there is a natural threshold experiment where school children with blood lead levels over a certain amount are treated to remove lead from their home environment (and their bodies) while other children just below the same lead level were not treated. The difference in later life outcomes are stark.

There is no such natural experiment for abortion. It's just an idea.

https://ftp.iza.org/dp10872.pdf

I'm not in the slightest challenging that lead is terrible for IQ; it's the link to national crime stats that I think is more tenuous.

https://jabberwocking.com/has-the-lead-crime-hypothesis-been...

The remainder can be explained by bread and games = cheap food and game consoles which kept the kids playing in the house instead of being part of a gang.

Maybe it was rather the removal of "lead victims" that led to the sudden reduction of crime.

But then there's been a huge rise in crime. The murder rate in some cities is dramatically higher than just a few years ago. But it's not like the gas suddenly became leaded again.

This makes me think that we just can't be too certain about these things.

> But then there's been a huge rise in crime

Is this actually true? I've seen a lot of people saying this politically but haven't seen a lot of data to back it up. From what I've seen there's been a slight bump, which isn't too surprising given the state of everything... but it's still massively dwarfed by the decrease in the 90s and 00s

For example https://www.bbc.com/news/57581270

Here property crime was up a little bit but violent crime was way up (50% or so). I personally think it's the stress and anxiety of lost jobs, loss of release valves (going to the office, seeing friends, etc). I believe it's a temporary spike and will fade in the next year or two.

https://www.pewresearch.org/fact-tank/2021/10/27/what-we-kno...

Thanks! this supports the fact that it's still lower than before the 90s decline, and possibly pandemic related. I guess we'll find out over the next few years.

> Despite rising sharply in 2020, the U.S. murder rate remains below the levels of the early 1990s.

> Americans remain far less likely to die from murder than from other causes, including from suicide and drug overdose.

From what I've seen there has been a recent rise in the murder rate. In some places it was at historical highs--but the cities are also much, much larger now. When looking at per-capita data its still historically low.

You're right in that there doesn't seem to be a definitive cause, but quite a few things have changed since Covid started and we're not sure what changes are permanent.

That probably means that the main reason for the crime rate spike since the 60s is not lead but something else.

There was not huge rise in crime in general. There were more murders during lockdowns in US, which is in fact to be expected since people were forced to be with close relatives - and most murders are by close people.

Murders have been on the rise since 2014 or so

No. They went up in 2014 and 2015. They went down in 2016, 2017 and 2018.

Sure but it was an immensely stressful time for lots of people, that is going to drive up crimes of all types. Expect a similar (is not as drastic) drop in crime as well over the next couple of years.

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