Just a friendly reminder to keep this thread to debate, and not personal attacks. No wrong done thus far, but I can see this getting quite heated and I don't want to have to close the thread
As to a 7 year old feeding lizards to a croc, and 'bludgeoning them to death' - I don't think that's natural behaviour for any human, 7 years old or not. I was a very inquisitive child, and was especially interested in biology (even went to uni to study it). I've done dissections and also hunted (rabbits) for food, and I can honestly say I and nobody I've ever known would think it was ok to do what this child did.
I'm not convinced that cruelty to animals leads to a killer mindset in the majority of cases, and perhaps this child thought what they were doing wasn't bad, but in that case I'd have to question what sort of parenting he had received, and why the child went to the lengths of scaling fences to break into a zoo to do what he did.