But scientists have suspected that modern humans may have interbred with other now-extinct human groups that have not been identified yet. They focused on ancestors who had profound genetic differences from modern humans ‪—‬ a sign they evolutionarily split from the modern human lineage a long time ago. The researchers said one ghost lineage's DNA was found in all modern humans. "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." This newfound lineage's DNA constitutes about 0.5% to 1% of the genomes of modern humans, comparable to the amount of Neanderthal DNA in many people living today.