I am been aggressive here though the event may well have taken place much earlier to produce an early version of the naked ape. On the face of it that appears likely. Yet the rapid emergence of modern humanity is recent and not evolutionary at all. Also our bipedal primate is plausibly a chimp branch which was hybridized recently. Once you know you are looking for hybridization it becomes possible to narrow it down to before and after. The DNA markers will be there.
At the request of the author i have excised the bulk of this important paper. I have left the first few paragraphs whith i underlined for my needs.
##### subsatacial redaction here