Researchers from the University of Liverpool have identified the genetic basis of how mice can recognise close relatives, even if they have never encountered them before

In the study, researchers demonstrated that a species-specific genetic marker called the major urinary protein (MUP), which is detected through the animal's scent, is used by female house mice to select closely related females as nest partners to help look after their offspring. The researchers also showed that another scent-based genetic marker, the vertebrate-wide major histocompatibility complex (MHC), is not involved in kin recognition, contrary to previous assumptions that this is how most animals recognize their relatives. It is well established that animals, including people, bias cooperation towards close relatives because it increases the odds of the genes that they share with relatives being passed to the next generation. Female house mice can breed cooperatively and usually select relatives as nest partners regardless of prior familiarity, but the genetic markers involved in this recognition have proven extremely difficult to identify. Previous work by the team provided the first hint that MUP but not MHC might provide a genetic kinship marker to avoid inbreeding with close kin, but could not prove the mechanisms involved. The next step for researchers is to investigate if other species have evolved similar genetic markers to recognize their relatives and, if so, whether these signals evolve only in species that cooperate with relatives to increase their breeding success.