MESSY AND MALADADAPTIVE. “Some theorists have argued that the eukaryotic nucleus is the more primitive, burdened with inefficiencies left over from a rather messy origin of cellular life. Others, as we noted earlier, see it as replete with maladaptive genomic accumulations, which may or may not affect regulation of gene expression.”
http://www.pnas.org/content/112/33/10278.full