For a book about the all-too-human “passions of war,” my 1997 work Blood Rites ended on a strangely inhuman note: I suggested that, whatever distinctly human qualities war calls upon—honor, courage, solidarity, cruelty, and so forth—it might be useful to stop thinking of war in exclusively human terms. After all, certain species of ants wage war and computers can simulate “wars” that play themselves out on-screen without any human involvement. More generally, then, we should define war as a self-replicating pattern of activity that may or may not require human participation.