If it can be ascertained experimentally that the 3X3 Majorana neutrino mass
matrix M_nu has vanishing determinants for one or more of its 2X2 submatrices,
it may be interpreted as supporting evidence for the theoretically well-known
canonical seesaw mechanism. I show how these two things are connected and offer
a realistic M_nu with two zero subdeterminants as an example.Comment: title changed, version to appear in PRD(RC