Not just Neanderthals: Ghost lineage in Africa left its mark on our DNA

The narrative of human ancestry, as penned in the future, will undoubtedly place the interbreeding with Neanderthals and Denisovans at its core. It would be natural to compose this tale as a straightforward account: once we extracted genetic information from these other groups, we could pinpoint the shared sequences in our genomes.

However, the truth is more complex. As scientists delved deeper into vast data sets, they encountered recurring indicators of an enigmatic ancestry hidden within our genetic code. The challenge lay not only in identifying these traces but also in their variability. The average 2% of Neanderthal DNA present in numerous populations does not ensure that every individual would inherit the same proportion.

With the genomes of Neanderthals and Denisovans now at hand, researchers are poised to address a new inquiry: Are there additional ancestries? Utilizing advanced analytical methods, they have unearthed indications of a third lineage, implying a potential interbreeding event prior to the exodus of modern humans from Africa. Despite early hints of this occurrence, a genome from a contemporary human relative is still absent to elucidate the specifics. The enigmatic source of this DNA remains a "ghost lineage."