Maybe ten years ago, Henry was analyzing some retrotransposons, sequences that randomly make and insert more copies of themselves. These mutations are statistically simpler in some ways that nucleotide substitutions: insertions are unique.
Henry had gotten some sign reversed while I was distracting him, so for a moment it looked as if modern humans had originated in Southeast Asia, instead of Africa or nearby. So the new task was to come up with a scenario that might explain that. I was in a silly mood, which helped: took me about a minute to suggest that some of the Indonesian islands and their neighbors went back and forth between between being accessible during deep glacial maxima ( low sea levels, Indonesian archipelago turns into Sundaland) and separated most of the rest of the time: allowing for occasional colonization by archaic sapiens, isolation and local adaptation, maybe even speciation.
Since then we’ve found signs of Denisovan admixture in people in Melanesians ( PNG, Australia, the Solomons), hobbits on Flores, other little guys in the Philippines, and old tools in Sulawesi. Very likely we’re going to find Sulawesi man. I wouldn’t be surprised to see five or more separate archaic pops in those islands. Maybe derived erectus, maybe something earlier, maybe highly differentiated Denisovans, maybe all of the above and a few dark elves. I still don’t think they made to Australia, but I wouldn’t bet my life on it.
While it looks as if Neanderthals made it to Crete.
Since there were land bridges to Japan in glacial maxima, you’d have to to suspect that they had their own local archaic populations as well. To a decent approximation, if elephants could colonize a place, so could archaic humans.