A study of genic diversity and spatial autocorrelation of some cat populations has been carried out at the microgeographic (cities of Palma Majorca and Ibiza) and the macrogeographic (Balearic Islands and total Spain) levels. In both cases, the cat populations show high levels of gene flow (Nm) and few stochastic effects (e.g., genetic drift). Thus, cat populations are closer to the viewpoint of Mayr (1954)--that is, a species composed of large effective populations very near to panmixia--than to the hypothesis of demic structuration with very little gene flow between populations. The genetic differentiation between cat populations seems to be lower than that found in other vertebrate species. Nevertheless, I have found the existence of significant genetic heterogeneity at both the micro- and macrogeographical levels. At the microgeographical level, the differences in genetic heterogeneity at each of the loci studied within two populations could be caused by the introduction of the diverse mutant alleles into the analyzed populations at different historical times. At the macrogeographical level, the interaction of a strong differential gene flow caused by historical factors (and demographic changes) and, perhaps, natural selection for some loci is a possible explanation. The cat population data are in agreement with the hypothesis of Schwartz and Armitage (1980), who argued that social structures promote and augment gene flow between groups or populations of the same species. Humans seem to be the dominant element that explains the observed high rates of gene flow between cat populations.