Neanderthals or denisovans encountering sapiens probably would have been much like sapiens encountering sapiens of a different culture/tribe. Fighting, trading, cultural exchange and some breeding. They would have registered as different tribes but I doubt that the "species" concept (all sapiens unite to defeat the denisovan threat!) would have registered.
They weren't that different to us biologically, but people can be pretty different from eachother behaviourally) culturally. One tribe is nomadic, eats a lot of elephants, does monogamy and lives in big hierarchical groups. Another is settled, clannish, matriarchal, polygomous and does a lot of fishing. Behaviourally, that's a lot of difference.
It's possible that neighboring neanderthal tribes we're culturally more similar (food, language, art..) to your sapiens tribe than some far off sapiens tribe.
Also, it can be little bit misleading to think of those two as separate species. It's more that the human gene pool was much deeper then than now. We are all very close genetically today, especially for such a populous and widespread species. Back then, even within groups classed as Sapiens or Neanderthals, the genetic (and to an extent, morphological) diversity that existed was much bigger.
The newly discovered species though... Homo Naledi, florisiensis and luzonensis. These guys do seem like different species. Hopefully, some DNA will be found and we'll know more about them.
They weren't that different to us biologically, but people can be pretty different from eachother behaviourally) culturally. One tribe is nomadic, eats a lot of elephants, does monogamy and lives in big hierarchical groups. Another is settled, clannish, matriarchal, polygomous and does a lot of fishing. Behaviourally, that's a lot of difference.
It's possible that neighboring neanderthal tribes we're culturally more similar (food, language, art..) to your sapiens tribe than some far off sapiens tribe.
Also, it can be little bit misleading to think of those two as separate species. It's more that the human gene pool was much deeper then than now. We are all very close genetically today, especially for such a populous and widespread species. Back then, even within groups classed as Sapiens or Neanderthals, the genetic (and to an extent, morphological) diversity that existed was much bigger.
The newly discovered species though... Homo Naledi, florisiensis and luzonensis. These guys do seem like different species. Hopefully, some DNA will be found and we'll know more about them.