For the past four decades the compositional organization of the mammalian genome posed a formidable challenge to molecular evolutionists attempting to explain it from an evolutionary perspective. We have carried the most detailed analyses to describe mammalian genome composition thus far. We debunked the “isochore theory,” which argues that the genome consists of long stretches of homogeneous DNA, and showed that it actually consists of many short and few long domains. We also found evidence to that invalidate the Euarchontoglire clade, suggesting that primates are not closer to murids more than to Laurasiatheria. Our paper was published in PloS Computational biology.