It is like trying to pinpoint the exact location your walk through the forest became a walk through the swamp. There was no line, the forest just gradually becomes more and more swampy until you are no longer in a ‘swampy forest’ but more in a ‘foresty swamp’ and eventually - all swamp.
Looking for an exact line of demarcation, looking at your footprints and saying “this step was in a forest, but this step was in a swamp” - is sort of silly - but people like things to fit into neat little boxes, despite this often being inapplicable to reality.
Reading this I remembered my walk through the Koch brothers evolution exhibit at the Smithsonian. Near the end of a large string of skulls showing the gradual changes over 6 million years was a 12,000 year old skull classified as a homo sapien. I looked at this and said to myself, absolutely no way. It didn’t even look like Neanderthal. In fact it looked most like Heidelburgensis which died out much earlier than Neanderthal and was probably a precursor.
These “robust” skulls were from a site, Kow Marsh, in Australia, and have really fouled up the anthropoligical arguments in that continent. My theory, these were a Heidelburgensis remnant of people on the Australian continent from many, many thousands of years ago (perhaps from the low water period of the previous ice age, not our more recent one). The link below carries some of this argument, and also has a detailed theory as to why we have 1 to 4% Neanderthal genes, but no Neanderthal mitochondria, whereas the Neanderthal thus far studied (admittedly very few specimens) have no homo sapien genes.
http://www.convictcreations.com/aborigines/prehistory.htm