Since a dramatic peak in the 1980s, serial killers in the U.S. like Ted Bundy and Jeffrey Dahmer have been in decline for three decades. Experts have a few theories that can help explain why.
As previously mentioned, the typical age range for serial killers to start killing is in their late 20s to early 30s.
So figure that the people killing were maybe maybe late 20s to early 30s in late 1950s to 1970, when the numbers were exploding.
That means people born in ~1920 to ~1940; the serial killers probably were mostly born in the interwar period, between World War I and World War II; born in the Roaring Twenties and then the Great Depression.
Going based on the generations there, that would have mostly been the Silent Generation.
The period of rapid increase was only about twenty years long, so it’s really only about the length of one generation (though that doesn’t mean that it need nicely align with the “generational cohorts” thing).
The Boomers were already falling off.
By the time Generation X rolled around, the spike would already have been done.
Millennials were born between 1981 and 1996, long after all this happened.
And one other point – remember that the graph is of absolute, not per-capita numbers. According to it, in 2010, we have numbers in absolute terms comparable to about 1955. But that’s in absolute terms.
In 1955, the US population was about 106 million. Today, it is 334 million. That is, in per-capita terms, 2010 is somewhat-lower than any period shown on the chart. It’s not just low, it’s lower than it’s ever been.
Now, all that being said, I’m not sure how they measure the number of concurrently-active serial killers. I would imagine that things like the advent of DNA evidence, buildup of fingerprint databases, and other changes in criminology probably have changed things; one might have assumed that a serial killer was responsible for a copycat/similar crime, or perhaps vice versa in different conditions.
The other theory I’ve heard that makes some sense is lead exposure. From 1925 to about 1976, lead was commonly added to gasoline. Lead is known to cause psychological problems including irritablity and general mood disorders.
Pretty much everyone born during that period was exposed to aerosolized lead.
A 19-year-old – the youngest cohort listed – would be 33, maybe the end of the peak period to start serial killing – 14 years after 1944. That’s in 1958, and that’d have been the tail end of American WW2 veterans being in the prime serial killer initiation age. The boom had started then, but the highest rate of increase came later…and that’s looking at the very tail end of the WW2 vets.
The serial killers would mostly have been children or young teens during World War II, not actually served in it.
It might be interesting to see if countries other than the US – and I have no idea if whatever metrics used by the author here can be applied in those countries, might not have the same data available – saw similar changes in serial killer activity, since that’d help let one know if the relevant factors producing the spike were something that the US in particular experienced or not.
I think that the reduction in lead is far too late, if you figure that it’s cumulative exposure over someone’s lifetime, not short-term (which I have not looked up, but would expect to be the case).
In this cohort study of 553 New Zealanders observed for 38 years, lead exposure in childhood was weakly associated with official criminal conviction and self-reported offending from ages 15 to 38 years. Lead exposure was not associated with the consequential offending outcomes of a greater variety of offenses, conviction, recidivism, or violence.
Yeah, so it’s a childhood thing. You’d be talking about on the order of maybe a 20 year delay until a reduction in exposure translates into peak potential serial killer period.
Also, for stuff like lead paint, it’s gonna be around for decades, gets kicked up over time, so it takes an even longer time for regulations to go have an effect, and that effect is very spread out, whereas this is a pretty sharp increase and decrease.
In 1971, Congress banned the use of lead-based paint in residential projects (including residential structures and environments) constructed by, or with the assistance of, the federal government.[3] The Consumer Product Safety Commission followed with implementing regulations, effective in 1978.[4] Additional regulations regarding lead abatement, testing and related issues have been issued by the Environmental Protection Agency (EPA).
I’d – without digging up numbers – guess that halting leaded gasoline probably had the most-immediate impact on lead in the air, since burning leaded gasoline is gonna put it straight into the air.
In the U.S., the Environmental Protection Agency issued regulations to reduce the lead content of leaded gasoline over a series of annual phases, scheduled to begin in 1973 but delayed by court appeals until 1976.
If something were gonna happen in the 1970s to reduce the rate of serial killing, to be a relevant input, it’d have to be something that had a major immediate effect rather than a long-term developmental effect.
And leaded gasoline and leaded diesel and leaded aviation fuel and lead pipes in household plumbing. Probably lead in the cigarettes everyone smoked literally everywhere.
The rise started before 1950, rose the most rapidly from 1960 to 1970, plateaued in 1980, and then collapsed moving towards 2010.
https://www.ncesc.com/geographic-pedia/at-what-age-do-serial-killers-start-killing/
So figure that the people killing were maybe maybe late 20s to early 30s in late 1950s to 1970, when the numbers were exploding.
That means people born in ~1920 to ~1940; the serial killers probably were mostly born in the interwar period, between World War I and World War II; born in the Roaring Twenties and then the Great Depression.
https://en.wikipedia.org/wiki/Millennials
Going based on the generations there, that would have mostly been the Silent Generation.
The period of rapid increase was only about twenty years long, so it’s really only about the length of one generation (though that doesn’t mean that it need nicely align with the “generational cohorts” thing).
The Boomers were already falling off.
By the time Generation X rolled around, the spike would already have been done.
Millennials were born between 1981 and 1996, long after all this happened.
And one other point – remember that the graph is of absolute, not per-capita numbers. According to it, in 2010, we have numbers in absolute terms comparable to about 1955. But that’s in absolute terms.
https://www.populationpyramid.net/united-states-of-america/1955/
In 1955, the US population was about 106 million. Today, it is 334 million. That is, in per-capita terms, 2010 is somewhat-lower than any period shown on the chart. It’s not just low, it’s lower than it’s ever been.
Now, all that being said, I’m not sure how they measure the number of concurrently-active serial killers. I would imagine that things like the advent of DNA evidence, buildup of fingerprint databases, and other changes in criminology probably have changed things; one might have assumed that a serial killer was responsible for a copycat/similar crime, or perhaps vice versa in different conditions.
The other theory I’ve heard that makes some sense is lead exposure. From 1925 to about 1976, lead was commonly added to gasoline. Lead is known to cause psychological problems including irritablity and general mood disorders.
Pretty much everyone born during that period was exposed to aerosolized lead.
I don’t believe that it’s lead; see my other comment on it. The lead reductions would have come much too late, and the falloff is too sharp.
It’s always the quiet ones
I was thinking that people returning from WW2 might be a factor, war trauma or something, but that seems like it’s a little too early.
In 1944, this data shows the largest cohorts in an infantry unit being measured being 19-24 years old.
https://old.reddit.com/r/AskHistorians/comments/7c725k/what_was_the_average_age_of_the_soldiers_that/
A 19-year-old – the youngest cohort listed – would be 33, maybe the end of the peak period to start serial killing – 14 years after 1944. That’s in 1958, and that’d have been the tail end of American WW2 veterans being in the prime serial killer initiation age. The boom had started then, but the highest rate of increase came later…and that’s looking at the very tail end of the WW2 vets.
The serial killers would mostly have been children or young teens during World War II, not actually served in it.
It might be interesting to see if countries other than the US – and I have no idea if whatever metrics used by the author here can be applied in those countries, might not have the same data available – saw similar changes in serial killer activity, since that’d help let one know if the relevant factors producing the spike were something that the US in particular experienced or not.
so… lead paint?
I think that the reduction in lead is far too late, if you figure that it’s cumulative exposure over someone’s lifetime, not short-term (which I have not looked up, but would expect to be the case).
googles to sanity check
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5801257/
Yeah, so it’s a childhood thing. You’d be talking about on the order of maybe a 20 year delay until a reduction in exposure translates into peak potential serial killer period.
Also, for stuff like lead paint, it’s gonna be around for decades, gets kicked up over time, so it takes an even longer time for regulations to go have an effect, and that effect is very spread out, whereas this is a pretty sharp increase and decrease.
https://en.wikipedia.org/wiki/Lead-based_paint_in_the_United_States
I’d – without digging up numbers – guess that halting leaded gasoline probably had the most-immediate impact on lead in the air, since burning leaded gasoline is gonna put it straight into the air.
https://en.wikipedia.org/wiki/Gasoline#Lead_Replacement_Petrol
If something were gonna happen in the 1970s to reduce the rate of serial killing, to be a relevant input, it’d have to be something that had a major immediate effect rather than a long-term developmental effect.
And leaded gasoline and leaded diesel and leaded aviation fuel and lead pipes in household plumbing. Probably lead in the cigarettes everyone smoked literally everywhere.
This is really great info. Appreciate all the links backing up the data too. Thank you!
Maybe would be serial killers just spree kill in a mass shooting instead…that has certainly grown since Columbine
K