A side benefit of the stowaway behavior of mice is that sometimes it's possible to see the origins human populations from the context of other mice who came along. The concordance of these two species is evident in domesticus mice which colonized North America as well as South America, Australia and sub-Saharan Africa with Western European human counterparts ( Figure 2.3 ). An even more complicated case is seen in Japan, where the Japanese island's native mice were previously thought to be part of a different subspecies/species group known in literature as Mus molossinus. Molecular phylogenetic research has shown that Japanese mice are not part of a separate evolutionary line.