HOMO SAPIENS are a recent arrival on planet Earth, showing up late to the party a paltry 200,000 years ago. The young whippersnappers! And they–we–are only one branch on the Human family tree. The only branch, that we know of, that still exists, but still only one. In times gone past, our HOMO SAPIENS ancestors interacted with other species of Humans, creatures more bestial, at least in terms of their appearance, than we are, with out thinner skulls and larger brains and lighter skeletal structures. We fought with them, killed them, got killed by them, possibly ate them, possibly were eaten by them–and had sex with them. You may have a little touch of Neanderthal or Denisovian in your genetic pedigree.
Just how many other species of humans were there? We don’t really know. A recent study found that the DNA of members of the Yoruba population in Africa contains remnants of some unidentified Human species, possibly AUSTRALOPITHECUS HEIDELBERGENSIS. Or it might come from some Human species never documented before. There is also DNA present in the genetic cocktail of Melanesians that came from an extinct (we assume) species of Human whose DNA has never before been documented. That’s the part of the world where HOMO FLORESIENSIS is from, isn’t it? Hmmmm.