A recent meeting of the Mont Pelerin Society I organised in the Galapagos Islands on the theme of "evolution, thehuman sciences and liberty" brought together some of the world's leading neuroscientists, evolutionary psychologists, geneticists and social scientists to discuss what answer recent advances in these human sciences provide to the fundamental question, "what is human nature?".

One session was on the human animal as a warrior. Richard Wrangham provided an excellent summary of evidence on the evolutionary origins of human violence following his path-breaking book (with Dale Peterson), Demonic Males. He argued persuasively that war is part of our evolutionary psychology (particularly in males). His Harvard colleague Steven Pinker accepts this but argues that because of a complex set of social and cultural factors war may now be defunct. This was the view I disputed in my own paper.

I read Professor Pinker's monumental door-stopper of a book, The Better Angels of Our Nature, in my study in New Delhi in May. I could not help thinking that I was about six minutes flying time away from nuclear missiles from Pakistan to my west, and that to my north the heavily armed People's Liberation Army had just made an illegal incursion 12 miles into Ladakh. This made it difficult to believe that Professor Pinker's "better angels" were about to take over the world.

My own view of human nature was heavily influenced by David Hume, who wrote: "There is some benevolence, however small ... some particle of the dove kneaded into our frame, along with the elements of the wolf and serpent." From Professor Pinker's comprehensive survey of the mounting neuroscientific and socio-biological evidence, it is clear that the genial Scot, sitting in his study contemplating his fellow creatures, had got it right.

Where Professor Pinker has gone wrong is in attributing what he terms the Long Peace to the various social processes he discusses at length; they have allowed the dove to tame the wolf and the serpent in at least the developed countries. In my own book on war and peace, In Praise of Empires, I developed a framework that emphasised the importance of empires (or global hegemons) - the equivalent of Thomas Hobbes' Leviathan in international affairs - in maintaining global order and thereby peace in an otherwise anarchical society. I surveyed the rise and fall of empires since antiquity to show how they provided the order needed to pursue the elementary and universal goals that David Hume maintained any society must pursue for any social life to exist. These are: first, to secure life against violence that leads to death or bodily harm; second, that promises once made are kept; third, the stabilisation of possessions through rules of property. Through their Pax, these empires maintained peace and prosperity, and their decline and fall led to both domestic disorder and the disintegration of the enlarged economic spaces they had created.

True, these ancient empires did not seek to end various barbarous violent practices that were very much part of their "cosmological beliefs", and Professor Pinker is right in stating the importance of what he calls the "civilising and humanitarian processes", whose evolution I also traced in myUnintended Consequences. But nevertheless these have been insufficient to tame the instincts of the wolf in all civilisations, and the role of empires in maintaining peace and prosperity in their domains cannot be gainsaid.

Thus, despite its abhorrent cultural practices by the standard of contemporary norms, the Roman Empire had, through its Pax Romana, brought unprecedented peace and prosperity to the inhabitants of the Mediterranean littoral for nearly a millennium. When it collapsed, the ensuing disorder and the destruction of the imperial economic space led to a marked fall in the standards of living of the common people inhabiting the fallen empires.