Is the mourning behaviour exibited by elephants instinctual or learned?

As you've noted, it's an extremely difficult and complex question. Ethological studies have demonstrated that elephants will stop for some time to mourn the passing of even unrelated animals but the specific reason is - and may remain forever - unknown. However, simply asking is it learned or instinctive behaviour is oversimplifying the issue.

Elephants are extremely intelligent, emotional and social animals, much like ourselves. And,much like ourselves, they have been shown to exhibit evidence of sentience - being self-aware. Our own reactions to the passing of loved ones are governed by our experiences and influences through our lifetime and it may be that this is true of those animals - such as elephants - which are capable of sentience.

It is noteable that calves, upon seeing their first elephant corpse, will behave like the rest of the herd, almost automatically. Is this instinctive? It's impossible to say.

There may be pheremone cues, subtle behavioural signals, subsonic ... more.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.