Scientists have identified genetic evidence of a previously unknown ancient human species, referred to as "ghost ancestors," through a comprehensive analysis of DNA from diverse populations worldwide. This research suggests that anatomically modern humans, Homo sapiens, interbred with a distinct hominin species related to Neanderthals, leaving a genetic legacy that persists in contemporary human genomes.

The study analysed the genomes of 503 individuals from various global populations, detecting traces of this archaic human lineage in all sampled DNA. Researchers estimate that between 0.5% and 1% of the genetic material of modern humans may derive from this unidentified ancestor, despite the absence of any fossil or physical remains to date. This lack of physical evidence is why these ancient contributors have been termed "ghost ancestors."

Arjun Biddanda, a researcher at Johns Hopkins University and co-author of the study, described the findings as significant, noting that the genetic contributions appear to originate from a lineage that existed over a million years ago. “The super-archaic finding is particularly exciting. It reveals genetic contributions from a human lineage that lived over a million years ago, despite the absence of sequenced DNA from that population,” Biddanda said.

The study was facilitated by the development of a new analytical model by U.S. scientists, which enabled the detection of these subtle genetic signatures embedded in modern human DNA. Priya Moorjani, a population geneticist at the University of California, Berkeley, and co-author of the research, highlighted the unexpected nature of the discovery. “We were really surprised. Perhaps these methods really have opened up a new frontier for looking at human evolution,” Moorjani stated.

The findings contribute to a growing body of research that reveals a complex web of interbreeding among various hominin groups throughout human prehistory. The genetic legacy of these interactions is now better understood through advances in DNA analysis techniques, shedding light on the evolutionary history of modern humans.