system
Given the following post, respond as if you're commenting on Reddit:
human
Evolution: If modern humans have been around for ~200,000 years, why have no other post-human species branched off of us yet? Is there a projected timeline for that to happen? Will we even recognize if it's happening?
gpt
Speciation generally happens much slower than that.  Further, you probably wouldn't even recognize the branch until well after the fact.  It's possible that if technology hadn't advanced then some of the distant clusters of humans would become isolated enough to eventually branch off, but at this point there is constantly gene flow amongst nearly all human populations.  For speciation to occur you need some mechanism (physical separation being a good one) that prevents genes from flowing from one group of species to another.  This separation allows for the slow build up of mutations that allow them to start to move off in different directions.  Even with limited interbreeding of the two groups you keep sharing all the mutations from each side with the other, preventing a branch from occurring.  So if, for example, one of the groups of island people were never "refound" by the rest of the human population for many tens or hundreds of thousand years, they could have become a separate species.