The problem with using DNA is to try to determine ultimate geographical origin based on where this or that DNA bit survives today. The technology has been improving remarkably, such that DNA sequences can be extracted from very, very old remains, much moreso than might have been suspected even ten years ago.
Sore, at this point in our knowledge it’s very reasonable to work on the assumption that new races contributed the new genes.
But we may discover they’re just beneficial changes by radiation.
Intriguing that the Laschamp Event (75% weakening of the magnetosphere) happened 41,400 (±2,000) years ago: roughly approximating the time of the ‘new’ races in SE Asia.
just something to bear in mind!
What I really want found is evidence of the “giants” mentioned in practically all myths- not ‘Hobbits’!