Overview
Haplogroup R1-M173 is the SNP-defined root of the R1 lineage and one of the two primary branches of R-M207, the other being R2-M479. R1-M173 likely arose during the Late Upper Paleolithic, in a broad region that includes parts of north central Eurasia and possibly adjacent areas of the Near East. Its early carriers were hunter gatherers living in cold steppe and forest steppe environments at the end of the last glacial period.
Over time, R1 gave rise to two enormously successful lineages, R1a and R1b, which today dominate the paternal landscape of much of Europe, Central Asia and parts of South Asia and the Near East. R1a is strongly associated with Eastern European, Central Asian and Indo-Iranian populations, while R1b is most frequent in Western Europe and also appears in the Caucasus, Anatolia, the Near East and parts of Africa. Together, these branches account for a large proportion of the Y chromosome diversity in western Eurasia.
Basal R1-M173 without assignment to R1a or R1b (R1*) is very rare in modern datasets and is more often inferred from ancient DNA. Some debates have focused on whether rare R1 lineages found in Africa or the Americas reflect deep ancient dispersals or more recent back-migrations and admixture. Current evidence generally supports a Eurasian origin for R1, with most R1 in Africa and the Americas introduced relatively recently via historic or prehistoric movements from Eurasia.
Geographic distribution
As a root node, R1-M173 is best represented by the combined distributions of R1a and R1b. These lineages are extremely common across Europe, the Caucasus and western Siberia, and appear at substantial frequencies in Central and South Asia and parts of the Near East. Isolated and often low-frequency R1 lineages occur in North Africa and among some populations in sub-Saharan Africa, usually interpreted as the result of back-migration from Eurasia.
Ancient DNA
- Mesolithic and Neolithic hunter gatherer remains from Eastern Europe and parts of Russia show early R1 and R1a lineages that descend from R1-M173.
- R1-linked lineages are found in ancient individuals from the Pontic-Caspian steppe, which later contributed significantly to Bronze Age populations in Europe and South Asia.
- R1b-related lineages associated with R1-M173 appear in ancient remains from the steppe, the Caucasus and later in early Bronze Age western European contexts.
- Rare possible basal R1* or very early R1a/R1b lineages have been reported in both ancient and modern samples but remain poorly represented.
Phylogeny & subclades
R1-M173 splits into two major branches: R1a (R-M420) and R1b (R-M343). R1a further divides into Z282 and Z93, while R1b gives rise to L23, V88 and the dominant western Eurasian branches under M269. Basal R1* is defined as R1-M173(xR1a,R1b) and is rarely observed.
- R1a (R-M420)
- R1b (R-M343)
- Rare basal R1* (R1-M173(xR1a,R1b))
Notes & context
In this atlas, the generic entry "R1" describes the macro-lineage conceptually, while R1-M173 represents its SNP-defined root. Nearly all modern R1 chromosomes fall into R1a or R1b, reflecting large Holocene founder events on top of this older Upper Paleolithic background.
References & external links