In Central Italy, one hundred kilometers from Rome, a small group of 50 brown bears lives in complete isolation. This study reveals an extraordinary landscape of extremely low genetic variation. The question is: how could the Apennine bears have resisted for such a long time at very low population size and be apparently in good shape? Surprisingly, few genomic regions with very high diversity stand out from the low and flat background characterizing the rest of the genome. These regions are...