Is not nationalism - that devotion to a flag, an anthem, a boundary so fierce it engenders mass murder - one of the great evils of our time, along with racism, along with religious hatred? These ways of thinking - cultivated, nurtured, indoctrinated from childhood on - have been useful to those in power, and deadly for those out of power.
If racism can't be shown to be natural then it is the result of certain conditions, and we are impelled to eliminate those conditions.