Pb(CH2CH3)4.

[Plane]

Pb(CH2CH3)4.

..............if you chart the rise and fall of atmospheric lead caused by the rise and fall of leaded gasoline consumption, you get a pretty simple upside-down U: Lead emissions from tailpipes rose steadily from the early '40s through the early '70s, nearly quadrupling over that period. Then, as unleaded gasoline began to replace leaded gasoline, emissions plummeted.
 
Gasoline lead may explain as much as 90 percent of the rise and fall of violent crime over the past half century.
 
Intriguingly, violent crime rates followed the same upside-down U pattern. The only thing different was the time period: Crime rates rose dramatically in the '60s through the '80s, and then began dropping steadily starting in the early '90s. The two curves looked eerily identical, but were offset by about 20 years.
...........
........So Nevin dove in further, digging up detailed data on lead emissions and crime rates to see if the similarity of the curves was as good as it seemed. It turned out to be even better: In a 2000 paper (PDF) he concluded that if you add a lag time of 23 years, lead emissions from automobiles explain 90 percent of the variation in violent crime in America. Toddlers who ingested high levels of lead in the '40s and '50s really were more likely to become violent criminals in the '60s, '70s, and '80s.

And with that we have our molecule: tetraethyl lead, the gasoline additive invented by General Motors in the 1920s to prevent knocking and pinging in high-performance engines. As auto sales boomed after World War II, and drivers in powerful new cars increasingly asked service station attendants to "fill 'er up with ethyl," they were unwittingly creating a crime wave two decades later.
.................During the '70s and '80s, the introduction of the catalytic converter, combined with increasingly stringent Environmental Protection Agency rules, steadily reduced the amount of leaded gasoline used in America, but Reyes discovered that this reduction wasn't uniform. In fact, use of leaded gasoline varied widely among states, and this gave Reyes the opening she needed. If childhood lead exposure really did produce criminal behavior in adults, you'd expect that in states where consumption of leaded gasoline declined slowly, crime would decline slowly too. Conversely, in states where it declined quickly, crime would decline quickly. And that's exactly what she found.

...................collected lead data and crime data for Australia and found a close match. Ditto for Canada. And Great Britain and Finland and France and Italy and New Zealand and West Germany. Every time, the two curves fit each other astonishingly well. When I spoke to Nevin about this, I asked him if he had ever found a country that didn't fit the theory. "No," he replied. "Not one."

http://www.motherjones.com/environment/2013/01/lead-crime-link-gasoline


I found this article very interesting.Reading the whole thing is worthwile, because they make a good case for the idea that we unwittingly poisoned ourselves with a crime causing drug.

[Xavier_Onassis]

I find this interesting.

I think that the use of birth control pills, which caused a decline in unwanted pregnancies, also had a hand in the declining crime rate.

[Plane]

I find this interesting.

I think that the use of birth control pills, which caused a decline in unwanted pregnancies, also had a hand in the declining crime rate.

How were they involved in te increase in crime that preceded?

[Xavier_Onassis]

I do not understand what you are talking about.

Please explain.

[Plane]

The introduction of tetraethyl lead fuel to an area was followed by an increase of youth violent crime with a twenty year lag, the reduction of leaded fuel was followed in twenty years by a reduction of violent crime.

This pattern was found in several diffrent times and places where the leaded fuel was introduced and removed on diffrent schedules.

This isn't proof, but it is a strong indicator and plausable so this deserves further investigation.

I think it plausable that less children per family and greater controll of the process of reproduction might improve the standard of living for a lot of people and allow greater recorces to be devoted to each child, but how did the onset of commonly availible birth controll coincide with increasing crime rates?