Scientists have discovered remnants of ancient human ancestors in the genetic code of modern humans, shedding light on our genetic heritage. Researchers unearthed DNA from two unidentified groups of hominins, the primate family that includes Homo sapiens and Neanderthals. One group emerged in Africa approximately 50,000 years ago, while the other ‘super archaic’ lineage of hominins dates back 1.8 million years.
These ancient groups are believed to have interbred with Denisovans, another extinct hominin group, much like Neanderthals. The genetic mixing took place in Eurasia, where Denisovans passed on the ‘super-archaic’ DNA to Homo sapiens thousands of years later. It is estimated that modern humans carry a similar amount of ‘ghost DNA’ from these ancient ancestors as they do from Neanderthals, accounting for about 1 percent of their genome.
Yulin Zhang, a researcher at UC Berkeley involved in the breakthrough, stated that approximately 2 percent of the modern human genome originates from archaic hominins. The ghost ancestry is distributed similarly among modern-day Africans and non-African populations, with each individual inheriting around 0.5 to 1 percent of their genome from this ancient lineage.
Arjun Biddanda, a postdoctoral researcher at Johns Hopkins University and co-author of the study, expressed excitement over the discovery of genetic contributions from a human lineage over a million years old. The presence of ‘ghost DNA’ in both African and non-African populations suggests extensive interbreeding occurred before Homo sapiens spread beyond Africa.
These findings support the notion that modern Homo sapiens are a mosaic of genes from extinct hominin species, indicating prolonged interbreeding among different groups over millennia to shape the genetic diversity seen in present-day humans.