Overview
Haplogroup R* represents the un-split, basal form of haplogroup R from which all later branches descend, including R1, R2 and several upstream ghost lineages. As the ancestral state of the R macro lineage, R* belongs to the earliest Upper Paleolithic populations inhabiting regions across Central Asia, Siberia and parts of the Iranian plateau. These groups formed a critical part of the deep ancestry underlying both West Eurasian and Ancient North Eurasian populations. Because nearly all modern carriers of haplogroup R descend from downstream branches such as R1 and R2, true R*(xR1,R2) is extraordinarily rare today. Most high resolution Y genome sequencing efforts have found only a handful of individuals who fall into basal positions closely related to the R* category. These lineages provide rare but valuable clues about the original geographic and demographic context in which haplogroup R emerged. Including R* in the atlas is essential for accurately representing the deep evolutionary history of R and providing a complete phylogenetic scaffold for all downstream expansions.