Overview
Haplogroup R-PF7558 is a rare but phylogenetically meaningful early branch positioned directly downstream of R-L63, one of the final upstream split points before the emergence of the better known R1 and R2 lineages. PF7558 likely formed among Upper Paleolithic populations inhabiting northern Central Asia or the southern periphery of the Siberian forest steppe. These groups were among the earliest expansions of anatomically modern humans into the northern Eurasian ecological zone, where environmental pressures and demographic bottlenecks helped define the early structure of paternal haplogroup R. PF7558 stands at a transitional moment in the R phylogeny: late enough to be close to the formation of R1 and R2, but early enough to retain features of the deep Paleolithic ancestry from which the lineage arose. Its rarity in modern populations suggests near total lineage turnover during later expansions dominated by R1b steppe herders and R1a linked Indo European cultures. However, the absence of modern representation does not diminish its historical importance, as PF7558 helps contextualize how the early R lineages interacted with climatic shifts and dispersal routes during the terminal Pleistocene. Ancient DNA evidence occasionally shows upstream signals associated with PF7558 in Paleolithic or Mesolithic Siberian hunter gatherers. These findings indicate that PF7558 related populations once played a role in the demographic networks connecting western Siberia, the Altai region and Central Asia.