這種田鼠名叫普拉里（Prarie Vole）。雄普拉里鼠一輩子只和將處女之身獻給它的雌普拉里鼠生活。雄普拉里鼠不但不會多看其它雌鼠一眼，甚至還會攻擊其它雌鼠。目前，科學家已經將普拉里鼠的癡情行為和它們腦中分泌的荷爾蒙聯系起來。科學家認為，這種荷爾蒙不但讓普拉里鼠夫婦間保持著長期穩定的伴侶關系，還讓他們天生就對可能破壞家庭的第3者具有進攻性。

Although monogamy in the animal kingdom is rare, it's far from boring. Consider males of this mouse-like species, for example. They will stick with the female they lost their virginity to. Far from eyeing other females, a mated male vole will actually attack other females. Scientists have traced this behavior to hormones in the rodent’s brain, which triggers lasting bond formation and increased aggression toward potential home wreckers.