With more advanced DNA analysis techniques available to researchers, our understanding of how humans spread across the globe seems to get more and more complicated. Not only did modern humans leave Africa to find a world populated with Neanderthals and the more mysterious Denisovans, but it seems that there may have been another as yet unidentified human added to the mix.
This conclusion is based on a recent whole genome analysis of DNA taken from people living on the Andaman Islands in Southeast Asia, as well as that of other Melanesians. When compared with those of people living in India, they found whole sections of DNA that did not match any currently known human species, with it neither derived from Neanderthals, Denisovans, or us. This, they argue in a study published in Nature Genetics, shows how the ancestors of people who now live in the Pacific may have been mating with an as yet unknown hominin.
The humans in question could feasibly be a whole new species, as the history of the human settlement in this region is notoriously complex. But it could also be explained by another species called Homo erectus, who we know to have been present in Southeast Asia and who may have overlapped with modern humans. Unfortunately, the fossil evidence of H. erectus have not been preserved significantly enough to allow for genetic analysis. So while it could be that the unnknown DNA is from H. erectus, there is currently no way to test it.