A nuclear 'fossil' of the mitochondrial D-loop and the origin of modern humans

Mammalian mitochondrial DNA sequences evolve more rapidly than nuclear sequences. Although the rapid rate of evolution is an advantage for the study of closely related species and populations, it presents a problem in situations where related species, used as outgroups in phylogenetic analyses, have accumulated so much change that multiple substitutions obliterate the phylogenetic information. However, mitochondrial DNA sequences are frequently inserted into the nuclear genome, where they presumably evolve as nuclear pseudogene sequences and therefore more slowly than their mitochondrial counterparts. Such sequences thus represent molecular 'fossils' that could shed light on the evolution of the mitochondrial genome and could be used as outgroups in situations where no appropriate outgroup species exist. Here we show that human chromosome 11 carries a recent integration of the mitochondrial control region that can be used to gain further insight into the origin of the human mitochondrial gene pool.