Anthropologists have questioned universal explanations of war. Some hold out the hope that war, like slavery, can be erased by wise collective decision- making. But warfare is too diverse and historically widespread to be cured by simple remedies.

Economic motives have always existed. A fight for salt or metals, gold and treasure, enslaved labour or access to trade routes, or oil and other resources has marked many of the world's violent conflicts. But ideological and religious confrontations have also driven war.

Hubristic warfare from Alexander to Napolean to Hitler was meant to establish dominion. The rise of Chinese power has provoked questions on whether potential conflict with US will descend into war.

The search for security can be found in every warlike episode, as frontiers feel fragile. Is war on the decline, with new forms of settling conflict, cyber-attacks, stresses and clashes of beliefs are only too visible in the emerging international order. And so, the future of war might not look very different from its past.