Thesis Open Access
ABSTRACT: The Gorilla Genome Project (Scally, 2012) showed that 30% of the gorilla genome introgressed into the ancestor of humans and chimpanzees, and that the two species diverged through lineage sorting with 15% ending up in Pan and another 15% in Homo. That introgression is the Pan-Homo split, hybridization, which led to speciation as the new hybrid lineages became reproductively isolated from one another.
The NUMT on chromosome 5 fits perfectly with the introgression speciation model, it was formed from mtDNA that had diverged as much as ~4.5 Myr at the time of introgression, perfect fit with the Gorilla/Pan-Homo split, and the mtDNA fragments that formed it were inserted at the time of the Homo/Pan split, and ended up in both the Gorilla, Pan and Homo lineages around the same time period, 6 million years ago. (Popadin, 2017)
Introgression from Gorilla caused the Human-Chimpanzee split.pdf