Scientists have known for years that ancient homo sapiens interbred with other human species, particularly the Neanderthals and Denisovans. 'We were actually able to find and map genomic locations in modern humans that are from this ghost lineage and show that this ghost ancestry is in all modern humans, not only in Africans.' The Denisovans were an ancient human species that lived in Eurasia 200,000 to 32,000 years ago. However, identifying the DNA traces of our ghost ancestors has proven significantly harder since we don't know what their genomes looked like. However, some of these ancient sections didn't match any of our known human relatives – revealing the presence of ghost ancestors.