Gene flow from the gorilla lineage in the Late Miocene as the "missing link"
ABSTRACT: The "missing link" as a concept comes from that there is no continuous evolutionary model for the origin of the human species. There is now conclusive evidence that the speciation of the Homo lineage was caused by the common ancestor of humans and chimpanzees interbreeding with the gorilla lineage around 6 million years ago, an event that also led to the speciation of the Paranthropus lineage. The hybridization of two separate lineages explains the absence of a single continuous lineage. Evidence for an interbreeding event in the Late Miocene can be seen as introgression of around 30% of the gorilla genome into the Pan - Homo clade, with lineage sorting between Pan and Homo where 15% of the gorilla genome is closer to humans, and another 15% being closer to the chimpanzee lineage. (Scally, 2012) The interbreeding event can also be read in the genomes of both Gorilla , Pan and Homo as fragments of mitochondrial DNA that during the event 6 million years ago was inserted into the genome as a NUMT ("nuclear mitochondrial DNA segment"), a pseudo-gene, that originates from the gorilla lineage (Popadin, 2017) and has been transferred to all three lineages.