learned which party was victorious, nor the cause of the war: but I felt for the rest of that day as if I had had my feelings excited and harrowed by witnessing the struggle, the ferocity and carnage, of a human battle before my door.” What is distinctive about ant battles and the deaths that ensue is that they are coordinated, with success driven by group size. As the biologist Eldridge Adams has demonstrated, bigger groups are more likely to win, more likely to kill a higher number of their smaller opponents, and less likely to incur any fatalities. Despite the similarities between ant and human battles, two differences undermine the usefulness of this analogy for understanding the evolution of lethal aggression in humans: ants are only a very distant evolutionary cousin, subject to extremely different pressures of social life, and their cooperative efforts are largely among individuals who are virtual genetic clones. When humans go to battle, cooperation is largely among unrelated individuals who are complete strangers. Of the small sample of species committing adulticide, chimpanzees are our best bet as they are closer evolutionary cousins and they join forces with kin and non-kin. To get a sense of lethal aggression in chimpanzees, consider the following description by the anthropologist David Watts and his colleagues concerning an attack by males of the Ngogo community of Uganda (emphasized words are mine): [Field Assistant] G. Mbabazi found 12 adult and three adolescent males, 10 of which had participated in the boundary patrol 2 days before ... in the eastern part of the Ngogo chimpanzees’ territory. They started another boundary patrol by quickly and quietly moving south and then east. At 0830 hr, they moved east through a field of elephant grass (Pennisetum purpureum), then reentered the forest and went toward the spot where BT, LO, and MO [three adult male chimpanzees] had been displaying 1 day before and the area where Ngogo males had patrolled th