Scientists uncover traces of two mysterious 'ghost' ancestors in human DNA

Scientists uncover traces of two mysterious 'ghost' ancestors in human DNA The new findings suggest modern-day humans are the result of thousands of years of interbreeding between various groups of primates called hominis - but only one survives today: Homo sapiens Scientists have identified traces of ‘ghost ancestors’ in human DNA to help explain our genetic makeup. Researchers found DNA from two unknown groups of hominis, the group of primates which include homo sapiens and neanderthals. One originates from Africa around 50,000 years ago, while the other ‘super archaic’ hominis lineage is much older at 1.8 million years old. It’s thought they interbred with Denisovans, another group of hominis which have since died out, like neanderthals. They mixed DNA in Eurasia and Denisovans shared the ‘super-archaic’ DNA with homo sapiens thousands of years later. It’s thought there is a similar amount of ‘ghost DNA’ in modern-day humans to that of neanderthals, around 1 percent. "We discovered that about 2 percent of the modern human genome is from archaic hominins," Yulin Zhang, one of the UC Berkeley researchers who made the breakthrough, said. "In the case of the ghost lineage, modern-day Africans and non-African populations both inherited similar amounts of ghost ancestry. Each individual has about 0.5 percent to 1 percent of their genome inherited from this ghost lineage." Arjun Biddanda, a postdoctoral researcher at Johns Hopkins University and a co-first author of the study, told Phys.Org : "The super-archaic finding is particularly exciting because it reveals genetic contributions from a human lineage that lived over a million years ago, despite the absence of any sequenced DNA from that population." It was previously thought ‘ghost DNA’ existed in modern-day African people, but the research has found it in equal measure among Africans and non-Africans, suggesting much of the interbreeding took place before homo sapiens began exploring beyond the continent. The findings also underscore theories that modern-day homo sapiens are made up of a mix of extinct hominis genes, suggesting the various groups interbred for thousands of years to produce the humans we see today.