While fighting over females is common among male animals in the wild, these fights rarely result in death. You can’t pass on your genes when you’re dead or badly injured. So why do the males in some colonies of the tiny spider mite (Stigmaeopsis miscanthi) display aggressive, and sometimes deadly, behavior against rival males, while the males in other colonies do not, and how did this behavior evolve? Recent research published in the journal Ecology and Evolution, led by Professor Yukie Sato of the University of Tsukuba, Japan, shows that if you are a male Stigmaeopsis miscanthi mite, where you live is likely to determine your level of aggression.