Modern Japanese people arose from 3 ancestral groups, 1 of them unknown: DNA study

[qijia]

Cold adaptation in Upper Paleolithic hunter-gatherers of eastern Eurasia
Abstract
Previous genomic studies understanding the dispersal of Homo sapiens have suggested that present-day East Eurasians and Native Americans can trace their ancestry to migrations from Southeast Asia. However, ineluctable adaptations during the Last Glacial Maximum (LGM) remain unclear. By analyzing 42 genomes of up to 30-fold coverage from prehistoric hunter-gatherers, Jomon, we reveal their descent from Upper Paleolithic (UP) foragers who migrated to and isolated in the Japanese archipelago during Late Pleistocene. We provide compelling evidence suggesting that these UP people underwent positive selection for cold environments, aiding their survival through the LGM facilitated by non-shivering thermogenesis and detecting it polygenically across multiple loci in the Jomon lineage. Our study pioneers the close estimation of the physiological adaptation of ancient humans by the paleogenomic approach.
https://www.biorxiv.org/content/10.1101/...91810v1?ct=

Actually I doubt that Jomon people adapted to cold environment. 
Modern north east asians had got two traits of Neotany and ABCC11 gene under cold environment.
I don't think the Jomon people has this kind of factors. 30% of japanese allele frequency below must be an effect of Jomon. Considering those, yangshao and west liao valley people would not be ancestors to modern northern east asian also.

According to Clive Bromhall who has a Ph.D. in zoology from Oxford University, "Mongoloid races are explained in terms of being the most extreme pedomorphic humans."
Mongoloid Race - Features - Neoteny (liquisearch.com)