Some YECs believe speciation occurred, transitionals and all, several hundred times as fast as evolutionists generally claim, and in the opposite direction!
Does this sound right to you?
I think some devolution has occurred. I.e. increased genetic disease, shorter lifespans, etc.
But I don't think Homo Erectus or Neanderthal was an apeman. They were just racial variants and in many ways they may have beenn genetically equal or may have been superior genetically to humans today.