Monogamy is a pretty strange thing in the animal world. Some animals do it, but most don’t. Sometimes, it brings clear practical advantages, but other times, it’s not apparent why some animals are monogamous. This also goes for mice. The new study looked at the deer mouse (Peromyscus maniculatus), which ranges all across North America, and the oldfield mouse (Peromyscus polionotus), which mostly lives in Florida and Georgia. The mice are similar in many ways and are closely related biologically. However, their love life is vastly different. Whereas the oldfield mouse mates for life, the deer m…