Ethology is the science of the psychology of species behaviour.
When a species of animal becomes overpopulated or even just feels overpopulated, it begins to go insane. Experiments have been done with rats in the lab and with deer on an island. When the population reaches critical mass, behaviours change.
Even rats have courting rituals but when they are overpopulated and crammed into a small space, they engage in rat rape. Also the mothers disregard their young to engage in behaviours that are unusual in a normal rat society.
Normally the Alpha (dominant) rats mate while the Beta (submissive) rats don’t. Under stressed conditions the Beta rats form gangs and kill the Alpha rats and rape the female rats. Some of the female rats actually prefer the gang rats and help them kill their young.
Has the human species reached Critical Mass? Is that the reason the mass slaughters have been taking place and increasing in number?
Virginia Tech is another example of extremely aberrant behaviour. Do the principles of Ethology apply to the human animal? It would appear that they do.