A · BT · CT · F · K · K2 · K2b · NO · N · N2 · N2b
N2b
N2b represents a set of rare and phylogenetically deep lineages within the N2 cluster that did not participate in the more visible west Eurasian dispersal of N2a. Instead, N2b appears to have remained at low frequency among northern and central Eurasian populations, likely within small foraging and later mixed agro pastoralist communities. Its presence confirms that N2 as a whole once had a broader distribution across northern Eurasia than is suggested by its modern rarity.
Documented N2b lineages are extremely infrequent and scattered. They have been reported in small numbers among populations of central Asia, the Altai–Sayan region, Siberia and occasionally in eastern Europe or the Caucasus. Because sample counts are very low, current distributions should be viewed as provisional and subject to revision as more high coverage sequencing becomes available.
N2b consists of several poorly sampled downstream branches that diverged from the N2 trunk after N2a had already formed. Owing to limited sequencing, many N2b lineages remain provisionally classified, with only a handful of named SNP clusters.
N2b is a good example of how deep time lineages can persist at very low frequency. As additional Y chromosome data from Siberia and central Asia accumulates, the structure and distribution of N2b will likely be clarified and may reveal previously unrecognized prehistoric population layers.