Plenty of species kill their own kind, and I’ve read that ants and chimps, among others, will make the equivalent of war on each other. And to say rats have never done any good to anyone or for anything is to ignore the thousands, probably millions, of rats and mice that are killed for science and whose deaths have helped find important medical information about diet, medications, operations, genetics, and intelligence.

One person wrote in that spiders kill each other after “sexxing.” At first, I thought she’d written “sexting,” engendering visions of spiders I’d never before imagined. I guess they die happy.