Reply to Sashikumar's comment on Violent elephants

Thanks for the comment, Sashi. The PTSD theory is only one of the many theories to explain violence in captive elephants. The fact that male elephants are prone points to a role of the male sex hormones. It is well known that male hormones are implicated in violent behaviors. Hence female elephants may be expressing their 'feelings' in non violent ways.
Violence has been linked to low level of serotonin in brain. There is also evidence to show that people exposed to violence are more prone to violent behavior. Children disciplined using corporeal punishments inflict the same as parents later.
Both these factors - low serotonin and exposure to violence - may be responsible for some elephants becoming more aggressive.

Like us, animals also can vary in their propensity to become violent. It is true that a few such 'rogue elephants' are implicated in majority of violent incidents. Whether majority of such rogues have past history of exposure to violence has to be studied. Similarly the role of neurotransmitter levels and history of violent behavior in elephants.
It is curious to observe that psychiatry is the only branch of medicine without an equivalent in veterinary science, though animal psychology exists.