The paper notes as much: > Since Y. pseudotuberculosis is genetically very similar to Y. pestis, we hypothesised that NOD2 mutations may have provided a surviv

The paper notes as much: > Since Y. pseudotuberculosis is genetically very similar to Y. pestis, we hypothesised that NOD2 mutations may have provided a survival advantage to mutation carriers in the past during plague epidemics. As supposed, the current frequencies of CD-associated NOD2 mutations [ie, in the offspring of plague survivors] are correlated with the intensity of past Y. pestis epidemics in European and Mediterranean countries.