My thought exactly. Also the interesting point that the N genes found in modern man date back more to 60,000 years ago. It may be that our species and theirs were so diminished by the 74,000 Toba megavolcano event. That some mating from desperation and loneness may have occurred. Also, I vaguely remember reading the earlier Neanderthals may have been less brutish in physical ways than the late ones. Finally, I had the impression from studying the wall of skulls in the Smithsonians new mankind exhibit that Ns were the next step after Heidelbergensis humans who were already in Europe.