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It is widely claimed that children who injure or kill animals as children are more likely to exhibit violent behavior as adults, committing domestic violence or murder. A site dedicated to discussing "killer kids" describes "cruelty to animals & smaller children" as one of the "warning signs of kids who kill".

The People for the Ethical Treatment of Animals (PETA), who actually cite some sources, states that this goes both ways:

Acts of cruelty to animals are not mere indications of a minor personality flaw in the abuser; they are symptomatic of a deep mental disturbance. Research in psychology and criminology shows that people who commit acts of cruelty to animals don’t stop there—many of them move on to their fellow humans. “Murderers ... very often start out by killing and torturing animals as kids,” says Robert K. Ressler, who developed profiles of serial killers for the Federal Bureau of Investigation (FBI).

Studies have shown that violent and aggressive criminals are more likely to have abused animals as children than criminals who are considered non-aggressive. A survey of psychiatric patients who had repeatedly tortured dogs and cats found that all of them had high levels of aggression toward people as well. According to a New South Wales newspaper, a police study in Australia revealed that “100 percent of sexual homicide offenders examined had a history of animal cruelty.” To researchers, a fascination with cruelty to animals is a red flag in the backgrounds of serial killers and rapists. According to the FBI’s Ressler, “These are the kids who never learned it’s wrong to poke out a puppy’s eyes.”

Apparently, even as adults such individuals are still violent toward animals.

I know I learned to hunt and fish when I was young, and lots of other kids do too. It seems unlikely that all of us will turn out violent someday. Perhaps there's something about the demographic that learns to do such things at a young age that predisposes them toward violence, or maybe individuals making this claim have a narrower definition of violence than I.

At any rate, is there any evidence of a correlation between childhood violence toward animals and violent behavior as an adult (or vice versa)?

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I thought that the claim was that sociopathic, sadistic adults who hurt humans often start by, when they're children, hurting animals. – ChrisW Jun 13 '11 at 6:11
@randolf mosquito and ants are not animals? – Phelios Jun 13 '11 at 8:36
I think the important question is why is the person in question killing said animals, not simply whether they are doing so. – Rex M Jun 13 '11 at 15:28
"I think the important question is why is the person in question killing said animals" -- Or perhaps, "why not". Someone told me she'd seen a documentary about Australian history recently. – ChrisW Jun 14 '11 at 3:08
I may be repeating what some of the others have pointed out, but: 'a police study in Australia revealed that “100 percent of sexual homicide offenders examined had a history of animal cruelty.”' - without a control group this is meaningless. If they define animal cruelty broadly enough, it may be that 100% of non-offenders ALSO have a history of animal cruelty. More realistically, it may be that children who are cruel to animals still only have a tiny chance of becoming adult offenders. – Oddthinking Sep 7 '11 at 14:45

"Is there any evidence of a correlation?"

Yes. There are known common causes, and those are classified as empathy disorders. fMRI results show that empathy is a real, fundamental brain effect, and humans normally have empathy towards fellow humans as well as animals.

Now, that last result showed that empathy towards other people is not a good predictor for empathy towards animals. I can't obviously cite references for your particular case, but I expect you killed fish for food. That's another part of the brain, gathering food.

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If I were being sceptical I'd say that isn't evidence of correlation. What it is is offering an explanation or cause for the correlation (i.e. that it's caused by "lack of empathy"), assuming that there is one. However +1 for offering a link which purports to study the relative empathy of omnivores/hunters: i.e. for trying to begin to address the 2nd-last paragraph of the OP. – ChrisW Jun 14 '11 at 13:39
I don't think your references answer the question. The first defines a rather circular concept - those without a property called empathy are diagnosable as having no empathy. That doesn't show a correlation. The second is a non-peer reviewed student paper about another article (why not cut out the middle man and read/cite the article directly?) about the differences in brain function between a subset of vegans, vegetarians and omnivores. That doesn't show a correlation between (directly) injuring animals and humans. You may be right, but you haven't shown us that you are. – Oddthinking Sep 7 '11 at 14:51
"a real, fundamental brain effect" given that empathy is a kind of behaviour, clearly it is something to do with the brain. If fMRI can't detect a correlate with some form of behaiour does that mean its not "real"? – Raedwald Sep 8 '11 at 14:26
@Raedwald: No, that's faulty logic. You're confusing "sufficient" with "necessary". – MSalters Sep 8 '11 at 14:33
I think that there is an important, unaddressed issue here. Do these low empathy types make up a large fraction of the "kids who do bad stuff to animals" population, or are kids just meaner than adults? Secondly is there a threshold effect at which many kids do some bad stuff, but only the ones who will grow up to be violent adults cross some level of cruelty or repetition? – dmckee May 22 '12 at 21:19

I quote the Wikipedia article on psychopathy

Three behaviors — bedwetting, cruelty to animals and firestarting, known as the Macdonald triad — were first described by J.M. MacDonald as possible indicators, if occurring together over time during childhood, of future episodic aggressive behavior. However, subsequent research has found that bedwetting is not a significant factor and the triad as a particular profile has been called an urban legend. Questions remain about a connection between animal cruelty and later violence, though it has been included in the DSM as a possible factor in conduct disorder and later antisocial behavior.

and the one on Cruelty to animals, which makes the interesting point that there may be a common cause to both (I think this runs somewhat counter to this "evil shows itself early" think that I feel is associated with it)

It has also been found that children who are cruel to animals have often witnessed or been victims of abuse themselves. In two separate studies cited by the Humane Society of the United States roughly one-third of families suffering from domestic abuse indicated that at least one child had hurt or killed a pet.

Unfortunately I don't have access to this article though it promises to be a current review on the matter. This one I do have access to, they urgently call for more research, which may have happened in the meantime.

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