This is an extremely interesting thought, one I'm surprised I've never thought of before. Upon reading it, I jumped immediately to the civil rights question: How differently would we treat
Homo Erectus from our own species? I'm no expert on the amount of intelligence that
Homo Erectus had, but I would think that given the close relationship to our species, they might possibly have the capability of learning language. If we could actually have a conversation with
H. Erectus, would we treat them as our own species, as another animal, or somewhere in between?
For some reason, I seem to think that we would treat them not necessarily as full humans, but much closer to humans than any other animal. It's so strange to think about, though, I don't think one could ever know for sure.
Thanks for bringing that up!