Interesting - I would differ with him, substantially, especially since reading some of van der Dennen's stuff. I would say that the only reason we live in the paradigm we do now is BECAUSE of warfare, not DESPITE it.

But I think it is entirely possible for society to evolve characteristics that can later become threatening. A general nuke exchange wouldn't help humanity much, but eliminating a competing out-group can ensure your in-group's survival and increase cooperation within both groups, should the out-group survive and define a boundary.

There is some leadership theory that works in here, as well. Proponents of mono-culture and "unified, one-world governments" ignore an organizational dynamic where lots of small, competing groups create better and more solutions than one large "peaceful" group.