Haplogroup R1a

R1a origins The genetic divergence of R1a (M420) is estimated to have occurred 25,000 years ago, which is the time of the Last Glacial Maximum. A 2014 study by Peter A. Underhill et al., using 16,244 individuals from over 126 populations from across Eurasia, concluded that there was "a compelling case for the Middle East, possibly near present-day Iran, as the geographic origin of hg R1a". The ancient DNA record has shown the first R1a during the Mesolithic in Eastern Hunter-Gatherers (from Eastern Europe, c. 13,000 years ago), and the earliest case of R* among Upper Paleolithic Ancient North Eurasians, from which the Eastern Hunter-Gatherers predominantly derive their ancestry. The genome of an individual belonging to the R1a5 subclade, dated to 10,785–10,626 BCE, from Peschanitsa, Arkhangelsk, Russia, and identified as a Western Russian Hunter-Gatherer, was published in January 2021. Diversification of R1a1a1 (M417) and ancient migrations According to , the downstream M417 (R1a1a1) subclade diversified into Z282 (R1a1a1b1a) and Z93 (R1a1a1b2) circa 5,800 years ago "in the vicinity of Iran and Eastern Turkey". Even though R1a occurs as a Y-chromosome haplogroup among speakers of various languages such as Slavic and Indo-Iranian, the question of the origins of R1a1a is relevant to the ongoing debate concerning the of the Proto-Indo-European people, and may also be relevant to the origins of the Indus Valley civilization. R1a shows a strong correlation with Indo-European languages of Southern and Western Asia, Central and Eastern Europe and to Scandinavia being most prevalent in Eastern Europe, Central Asia, and South Asia. In Europe, Z282 is prevalent particularly while in Asia Z93 dominates. The connection between Y-DNA R-M17 and the spread of Indo-European languages was first noted by T. Zerjal and colleagues in 1999. Indo-European relation Proposed steppe dispersal of R1a1a proposed Ukrainian origins, and a postglacial spread of the R1a1 haplogroup during the Late Glacial Maximum, subsequently magnified by the expansion of the Kurgan culture into Europe and eastward. Spencer Wells proposes Central Asian origins, suggesting that the distribution and age of R1a1 points to an ancient migration corresponding to the spread by the Kurgan people in their expansion from the Eurasian steppe. According to , R1a1a diversified in the Eurasian Steppes or the Middle East and Caucasus region: Three genetic studies in 2015 gave support to the Kurgan theory of Gimbutas regarding the Indo-European Urheimat. According to those studies, haplogroups R1b and R1a, now the most common in Europe (R1a is also common in South Asia) would have expanded from the Pontic–Caspian steppes, along with the Indo-European languages; they also detected an autosomal component present in modern Europeans which was not present in Neolithic Europeans, which would have been introduced with paternal lineages R1b and R1a, as well as Indo-European languages. noted that R1a in South Asia most "likely spread from a single Central Asian source pool, there do seem to be at least three and probably more R1a founder clades within the Indian subcontinent, consistent with multiple waves of arrival." According to Martin P. Richards, co-author of , the prevalence of R1a in India was "very powerful evidence for a substantial Bronze Age migration from central Asia that most likely brought Indo-European speakers to India." Possible Yamnaya or Corded Ware origins David Anthony considers the Yamnaya culture to be the Indo-European Urheimat. According to , a massive migration from the Yamnaya culture northwards took place c. 2,500 BCE, accounting for 75% of the genetic ancestry of the Corded Ware culture, noting that R1a and R1b may have "spread into Europe from the East after 3,000 BCE". Yet, all their seven Yamnaya samples belonged to the R1b-M269 subclade, but no R1a1a has been found in their Yamnaya samples. This raises the question where the R1a1a in the Corded Ware culture came from, if it was not from the Yamnaya culture. According to Marc Haber, the absence of haplogroup R1a-M458 in Afghanistan does not support a Pontic-Caspian steppe origin for the R1a lineages in modern Central Asian populations. According to Leo Klejn, the absence of haplogroup R1a in Yamnaya remains (despite its presence in Eneolithic Samara and Eastern Hunter Gatherer populations) makes it unlikely that Europeans inherited haplogroup R1a from Yamnaya. Archaeologist Barry Cunliffe has said that the absence of haplogroup R1a in Yamnaya specimens is a major weakness in Haak's proposal that R1a has a Yamnaya origin. do argue for a Yamnaya origin of R1a1a in the Corded Ware culture, noting that several publications point to the presence of R1a1 in the Comb Ware culture.{{refn|group=note| refer to the following publications:{{ordered list|start=5 Proposed South Asian origins Kivisild et al. (2003) have proposed either South or West Asia, while see support for both South and Central Asia. Sengupta et al. (2006) have proposed Indian origins. Thanseem et al. (2006) have proposed either South or Central Asia. Sahoo et al. (2006) have proposed either South or West Asia. Thangaraj et al. (2010) have also proposed a South Asian origin. Sharma et al.(2009) theorizes the existence of R1a in India beyond 18,000 years to possibly 44,000 years in origin. A number of studies from 2006 to 2010 concluded that South Asian populations have the highest STR diversity within R1a1a, and subsequent older TMRCA datings. R1a1a is present among both higher (Brahmin) castes and lower castes, and while the frequency is higher among Brahmin castes, the oldest TMRCA datings of the R1a haplogroup occur in the Saharia tribe, a scheduled caste of the Bundelkhand region of Central India. From these findings some researchers argued that R1a1a originated in South Asia, excluding a more recent, yet minor, genetic influx from Indo-European migrants in northwestern regions such as Afghanistan, Balochistan, Punjab, and Kashmir. The conclusion that R1a originated in India has been questioned by more recent research, offering an argument that R1a arrived in India with multiple waves of migration. Proposed Transcaucasia and West Asian origins and possible influence on Indus Valley Civilization found that part of the Yamnaya ancestry derived from the Middle East and that neolithic techniques probably arrived at the Yamnaya culture from the Balkans. The Rössen culture (4,600–4,300 BC), which was situated on Germany and predates the Corded Ware culture, an old subclade of R1a, namely L664, can still be found. Part of the South Asian genetic ancestry derives from west Eurasian populations, and some researchers have implied that Z93 may have come to India via Iran and expanded there during the Indus Valley civilization. proposed that the roots of Z93 lie in West Asia, and proposed that "Z93 and L342.2 expanded in a southeasterly direction from Transcaucasia into South Asia", noting that such an expansion is compatible with "the archeological records of eastward expansion of West Asian populations in the 4th millennium BCE culminating in the so-called Kura-Araxes migrations in the post-Uruk IV period." Yet, Lazaridis noted that sample I1635 of , their Armenian Kura-Araxes sample, carried Y-haplogroup R1b1-M415(xM269) (also called R1b1a1b-CTS3187). According to the diversification of Z93 and the "early urbanization within the Indus Valley ... occurred at [5,600 years ago] and the geographic distribution of R1a-M780 (Figure 3d) may reflect this." note that "striking expansions" occurred within R1a-Z93 at c. 4,500–4,000 years ago, which "predates by a few centuries the collapse of the Indus Valley Civilisation." However, according to , steppe pastoralists are a likely source for R1a in India. ==Phylogeny==