One hormone system explains why some voles mate for life and others don't
Prairie voles form lasting pair bonds and share parenting duties, while their close relatives, meadow voles, mate promiscuously and never bond. Researchers traced much of the difference to how densely each species' brain is wired with receptors for oxytocin and vasopressin, and found that manipulating those receptors in the lab could make typically promiscuous voles bond monogamously.